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PRODUCTION AND EVALUATION OF RAPID TOOLING FOR ELECTRIC DISCHARGE
MACHINING USING ELECTROFORMING AND SPRAY METAL DEPOSITION TECHNIQUES
BY
RICKY BLOM
Submission for Master of Engineering (Research) School of Mechanical, Medical and Manufacturing Engineering
Queensland University of Technology
School of Mechanical, Medical and Manufacturing Engineering
February 2005
ii
ACKNOWLEDGMENT
Thank you to Associate Professor Prasad K.D.V. Yarlagadda and Dr R. Mahalinga-
Iyer for your support and guidance throughout the duration of the project. Also thank
you to all other staff at Queensland University of Technology that assisted in the
completion of this research.
Thanks to the staff at Queensland Manufacturing Institute and QMI Solutions with
special thanks to Dr Periklis Christodoulou and Geoff Wakeley for their help and
guidance while conducting the research and experiments.
The help from the Rapid Prototyping and Tooling staff at QMI Solution and
Concentric AMF was invaluable and the experiments would not have been possible
without their help.
Additional thanks goes to Steve Smith at Romar Engineering for assistance with the
electroforming process and producing the electroformed shells. Thank you also to
Ben Grams at Bocar Engineering for the production of the spray metal electrode
shells.
iii
ABSTRACT
To survive in today’s manufacturing environments companies must push the
standards of accuracy and speed to the highest levels possible. Electro Discharge
Machining (EDM) has been used for over 50 years and recent developments have
seen the use of EDM become much more viable. The goal of this research is to
produce and evaluate electrodes produced by different manufacturing methods.
The use of electroforming and spray-metal deposition has only recently become viable
methods of producing usable rapid tooling components. The speed and accuracy as
well as the cost of manufacture play a vital role in the tool and mould manufacturing
process. Electroforming and spray-metal deposition offer an alternate option to
traditional machining of electrodes.
Electroforming is one method of producing electrodes for EDM. The fact that
electroforming can be used to produce multiple electrodes simultaneously gives it the
advantage of saving on costs when multiple electrodes are needed. Spray-metal
deposition offers another alternative that is much cheaper and relatively faster to
manufacture.
The used of these non-traditional manufacturing methods in this research are
compared to the performance of traditional solid electrodes in terms of machining
time, material removal rate, tool wear rates and surface roughness at several standard
machining settings.
The results of this research are presented in this thesis along with conclusions and
comments on the performance of the different methods of electrode manufacture. The
major findings of the research include the solid electrodes performed better than the
electroformed electrodes in Material Removal Rate (MRR), Tool Wear Rate (TWR),
and Surface Roughness (Ra) at all machine settings. However it was found that the
production cost of the solid electrodes was six times that of the electroformed
electrodes.
iv
The production of spray metal electrodes was unsuccessful. The electrode shell walls
were not an even thickness and the backing material broke through the shell making
them unusable.
It is concluded that with further refinements and research, electroforming and spray
metal processes will become an extremely competitive method in electrode
manufacture and other rapid tooling processes.
v
DECLARATION
“The work contained in this thesis has not been previously submitted for a degree or
diploma at any other higher education institution. To the best of my knowledge and
belief, the thesis contains no material previously published or written by another
person except where due reference is made.”
Signed ………………………
Date …………………………
vi
TABLE OF CONTENTS
ACKNOWLEDGMENT................................................................................................ii
ABSTRACT................................................................................................................. iii
DECLARATION ...........................................................................................................v
TABLE OF CONTENTS..............................................................................................vi
LIST OF FIGURES ................................................................................................... viii
LIST OF TABLES..................................................................................................... xiii
PUBLICATIONS.........................................................................................................xv
1.0 INTRODUCTION ...................................................................................................1
1.1 AIMS AND OBJECTIVES..........................................................................................3
1.2 METHODOLOGIES ..................................................................................................3
2.0 LITERATURE REVIEW AND BACKGROUND .................................................5
2.1 RAPID PROTOTYPING AND TOOLING .....................................................................5
2.2 ELECTROFORMING ................................................................................................7
2.3 SPRAY DEPOSITION................................................................................................9
2.4 EDM...................................................................................................................10
2.5 LITERATURE REVIEW ..........................................................................................12
3.0 EXPERIMENTAL DESIGN ................................................................................16
4.0 EXPERIMENTAL PROCEDURE .......................................................................20
5.0 EXPERIMENTAL RESULTS .............................................................................26
5.1 EXPERIMENT 1 ....................................................................................................26
5.1.1 Solid Electrodes compared to Electroformed Electrodes ...........................27
5.1.2 Work pieces machined by different electrodes. ..........................................31
5.2 EXPERIMENT 2 ....................................................................................................35
5.2.1 Solid Electrodes compared to Electroformed Electrodes ...........................36
5.2.2 Work pieces machined by different electrodes ...........................................38
5.3 EXPERIMENT 3 ....................................................................................................41
5.3.1 Solid Electrodes compared to Electroformed Electrodes ...........................42
5.3.2 Work pieces machined by different electrodes ...........................................44
5.4 EXPERIMENT 4 ....................................................................................................47
5.4.1 Solid Electrodes compared to Electroformed Electrodes ...........................48
5.4.2 Work pieces machined by different electrodes ...........................................48
5.5 EXPERIMENT 5 ....................................................................................................51
5.5.1 Solid Electrodes compared to Electroformed Electrodes ...........................52
vii
5.5.2 Work pieces machined by different electrodes ...........................................53
5.6 EXPERIMENT 6 ....................................................................................................58
5.6.1 Solid Electrodes compared to Electroformed Electrodes ...........................58
5.6.2 Work pieces machined by different electrodes ...........................................59
5.7 SUMMARY OF ALTERNATIVE ELECTRODE MANUFACTURE AND PERFORMANCE
COMPARISON ............................................................................................................62
5.7.1 Detailed Failure Investigation of Spray Metal Electrodes..........................63
5.7.2 Cost Comparison.........................................................................................66
5.7.3 Performance Comparison of Manufacturing Methods ...............................69
6.0 CONCLUSIONS ..................................................................................................76
BIBLIOGRAPHY........................................................................................................79
viii
LIST OF FIGURES
Figure 2.1 – Electroforming Process .............................................................................8
Figure 2.2 – Spray Metal Deposition Process................................................................9
Figure 2.3 – Sodick Mould-Maker 3 NF40 .................................................................11
Figure 4.1 – SLA Electrode Master Patterns ...............................................................21
Figure 4.2 – Electrode grid measurements ..................................................................21
Figure 4.3 - Electrode Measurements before Experiment ...........................................22
Figure 4.4 - Electrode Measurements after Experiment ..............................................23
Figure 4.5 - Material removed from the electrode during the experiment...................24
Figure 5.1(a) – Base Electrode Wear Experiment 1 - Solid Electrode ........................28
Figure 5.1(b) – Base Electrode Wear Experiment 1 - Electroformed Electrode .........28
Figure 5.2 – Damage and excessive wear of Electroformed Base Electrode (EB1)....29
Figure 5.3 – Casting Inclusion and Electrode Wear ....................................................30
Figure 5.4 – Machining of triangle work piece in experiment 1 .................................31
Figure 5.5 – Failed Electroformed Electrode and Experiment 1 Work Piece .............31
Figure 5.6 – Electroformed Base Electrode for Experiment 1.....................................35
Figure 5.7 – Electroformed Base Electrode.................................................................36
Figure 5.8 – Electroformed cone electrode – Experiment 2 ........................................37
Figure 5.9 – Electroformed triangle electrode – Experiment 2 ...................................38
Figure 5.10 – Electroformed Base Electrode – Experiment 3 .....................................43
Figure 5.11 – Electroformed Base Electrode – Experiment 5 .....................................54
Figure 5.12 – Electroformed Cone Electrode – Experiment 5.....................................55
Figure 5.13 – Measurements of the different performances of Experiment 4 and
Experiment 5........................................................................................................55
Figure 5.14 – Electroformed Base Electrode – Experiment 6 .....................................59
Figure 5.15 – Defective spray metal shells ..................................................................63
Figure 5.16 – Sectional Views of Spray Metal Electrodes showing wall thicknesses 64
Figure 5.17 – Visual Surface Roughness comparison between Spray Metal (left) and
Solid Machined Electrodes (right) .......................................................................65
Figure 5.18 – Surface imperfection in the spray metal shells......................................66
Figure 5.19 – Machining time Comparison .................................................................70
Figure 5.20 – MRR Comparison..................................................................................71
Figure 5.21 – MRR Comparison for research by Leu, Yang and Yao [15].................72
ix
Figure 5.22 – TWR Comparison..................................................................................74
Figure 5.23 – TWR Comparison for research by Leu, Yang and Yao [15].................75
Figure A.1 - Cone Electrode Wear Experiment 1 - Solid Electrode............................85
Figure A.2 - Cone Electrode Wear Experiment 1 - Electroformed Electrode .............86
Figure A.3 – Triangle Electrode Wear Experiment 1 - Solid Electrode......................87
Figure A.4 – Triangle Electrode Wear Experiment 1 - Electroformed Electrode .......88
Figure A.5 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode - Solid Electrode Work Piece ......................................89
Figure A.6 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode - Electroformed Electrode Work Piece........................90
Figure A.7 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode - Solid Electrode Work Piece ......................................91
Figure A.8 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode - Electroformed Electrode Work Piece........................92
Figure A.9 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode - Solid Electrode Work Piece ......................................93
Figure A.10 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode - Electroformed Electrode Work Piece........................94
Figure A.11 – Base Electrode Wear Experiment 2 - Solid Electrode..........................95
Figure A.12 – Base Electrode Wear Experiment 2 - Electroformed Electrode ...........96
Figure A.13 – Cone Electrode Wear Experiment 2 - Solid Electrode .........................97
Figure A.14 – Cone Electrode Wear Experiment 2 - Electroformed Electrode ..........98
Figure A.15 – Triangle Electrode Wear Experiment 2 - Solid Electrode....................99
Figure A.16 – Triangle Electrode Wear Experiment 2 - Electroformed Electrode ...100
Figure A.17 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 2 - Solid Electrode Work Piece..............101
Figure A.18 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 2 - Electroformed Electrode Work Piece
............................................................................................................................102
Figure A.19 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 2 - Solid Electrode Work Piece..............103
Figure A.20 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 2 - Electroformed Electrode Work Piece
............................................................................................................................104
x
Figure A.21 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 2 - Solid Electrode Work Piece..............105
Figure A.22 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 2 - Electroformed Electrode Work Piece
............................................................................................................................106
Figure A.23 – Base Electrode Wear Experiment 3 - Solid Electrode........................107
Figure A.24 – Base Electrode Wear Experiment 3 - Electroformed Electrode .........108
Figure A.25 – Cone Electrode Wear Experiment 3 - Solid Electrode .......................109
Figure A.26 – Cone Electrode Wear Experiment 3 - Electroformed Electrode ........110
Figure A.27 – Triangle Electrode Wear Experiment 3 - Solid Electrode..................111
Figure A.28 – Triangle Electrode Wear Experiment 3 - Electroformed Electrode ...112
Figure A.29 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 3 - Solid Electrode Work Piece..............113
Figure A.30 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 3 - Electroformed Electrode Work Piece
............................................................................................................................114
Figure A.31 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 3 - Solid Electrode Work Piece..............115
Figure A.32 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 3 - Electroformed Electrode Work Piece
............................................................................................................................116
Figure A.33 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 3 - Solid Electrode Work Piece..............117
Figure A.34 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 3 - Electroformed Electrode Work Piece
............................................................................................................................118
Figure A.35 – Base Electrode Wear Experiment 4 - Solid Electrode........................119
Figure A.36 – Base Electrode Wear Experiment 4 - Electroformed Electrode .........120
Figure A.37 – Cone Electrode Wear Experiment 4 - Solid Electrode .......................121
Figure A.38 – Cone Electrode Wear Experiment 4 - Electroformed Electrode ........122
Figure A.39 – Triangle Electrode Wear Experiment 4 - Solid Electrode..................123
Figure A.40 – Triangle Electrode Wear Experiment 4 - Electroformed Electrode ...124
Figure A.41 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 4 - Solid Electrode Work Piece..............125
xi
Figure A.42 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 4 - Electroformed Electrode Work Piece
............................................................................................................................126
Figure A.43 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 4 - Solid Electrode Work Piece..............127
Figure A.44 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 4 - Electroformed Electrode Work Piece
............................................................................................................................128
Figure A.45 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 4 - Solid Electrode Work Piece..............129
Figure A.46 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 4 - Electroformed Electrode Work Piece
............................................................................................................................130
Figure A.47 – Base Electrode Wear Experiment 5 - Solid Electrode........................131
Figure A.48 – Base Electrode Wear Experiment 5 - Electroformed Electrode .........132
Figure A.49 – Cone Electrode Wear Experiment 5 - Solid Electrode .......................133
Figure A.50 – Cone Electrode Wear Experiment 5 - Electroformed Electrode ........134
Figure A.51 – Triangle Electrode Wear Experiment 5 - Solid Electrode..................135
Figure A.52 – Triangle Electrode Wear Experiment 5 - Electroformed Electrode ...136
Figure A.53 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 5 - Solid Electrode Work Piece..............137
Figure A.54 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 5 - Electroformed Electrode Work Piece
............................................................................................................................138
Figure A.55 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 5 - Solid Electrode Work Piece..............139
Figure A.56 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 5 - Electroformed Electrode Work Piece
............................................................................................................................140
Figure A.57 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 5 - Solid Electrode Work Piece..............141
Figure A.58 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 5 - Electroformed Electrode Work Piece
............................................................................................................................142
xii
Figure A.59 – Base Electrode Wear Experiment 6 - Solid Electrode........................143
Figure A.60 – Base Electrode Wear Experiment 6 - Electroformed Electrode .........144
Figure A.61 – Cone Electrode Wear Experiment 6 - Solid Electrode .......................145
Figure A.62 – Cone Electrode Wear Experiment 6 - Electroformed Electrode ........146
Figure A.63 – Triangle Electrode Wear Experiment 6 - Solid Electrode..................147
Figure A.64 – Triangle Electrode Wear Experiment 6 - Electroformed Electrode ...148
Figure A.65 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 6 - Solid Electrode Work Piece..............149
Figure A.66 – Base Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 6 - Electroformed Electrode Work Piece
............................................................................................................................150
Figure A.67 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 6 - Solid Electrode Work Piece..............151
Figure A.68 – Cone Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 6 - Electroformed Electrode Work Piece
............................................................................................................................152
Figure A.69 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 6 - Solid Electrode Work Piece..............153
Figure A.70 – Triangle Work Pieces Machined by Solid Electrode compared to
Electroformed Electrode Experiment 6 - Electroformed Electrode Work Piece
............................................................................................................................154
xiii
LIST OF TABLES
Table 3.1 – Machine Settings or Finishing, Semi-Roughing and Roughing Cuts.......17
Table 3.2 – Actual Settings or Finishing, Semi-Roughing and Roughing Cuts ..........17
Table 4.1 – CMM Coordinate measurements of the electrode height .........................22
Table 4.2 – Mass measurements and calculations taken from experiments ................24
Table 4.3 – Measurements of Ra from the Taylor Hobson Surtronic ..........................25
Table 5.2 – Machining Time for Experiment 1 ...........................................................33
Table 5.3 – Material Removal Rate for Experiment 1.................................................34
Table 5.4 – Tool Wear Rate for Experiment 1.............................................................34
Table 5.5 – Average Surface Roughness Ra μm, Experiment 1 ..................................35
Table 5.6 – Change in Mass for Experiment 2 ............................................................39
Table 5.7 – Machining Time for Experiment 2 ...........................................................40
Table 5.8 – Material Removal Rate for Experiment 2.................................................40
Table 5.9 – Tool Wear Rate for Experiment 2.............................................................41
Table 5.10 – Average Surface Roughness Ra μm, Experiment 2 ................................41
Table 5.11 – Change in Mass for Experiment 3 ..........................................................45
Table 5.12 – Machining Time for Experiment 3 .........................................................46
Table 5.13 – Material Removal Rate for Experiment 3...............................................46
Table 5.14 – Tool Wear Rate for Experiment 3...........................................................47
Table 5.15 – Average Surface Roughness Ra μm, Experiment 3 ................................47
Table 5.16 – Change in Mass for Experiment 4 ..........................................................50
Table 5.17 – Machining Time for Experiment 4 .........................................................50
Table 5.18 – Material Removal Rate for Experiment 4...............................................50
Table 5.19 – Tool Wear Rate for Experiment 4...........................................................51
Table 5.20 – Average Surface Roughness Ra μm, Experiment 4 ................................51
Table 5.21 – Change in Mass for Experiment 5 ..........................................................56
Table 5.22 – Machining Time for Experiment 5 .........................................................56
Table 5.23 – Material Removal Rate for Experiment 5...............................................57
Table 5.24 – Tool Wear Rate for Experiment 5...........................................................57
Table 5.25 – Average Surface Roughness Ra μm, Experiment 5 ................................58
Table 5.26 – Change in Mass for Experiment 6 ..........................................................60
Table 5.27 – Machining Time for Experiment 6 .........................................................61
xiv
Table 5.28 – Material Removal Rate for Experiment 6...............................................61
Table 5.29 – Tool Wear Rate for Experiment 6...........................................................62
Table 5.30 – Average Surface Roughness Ra μm, Experiment 6 ................................62
Table 5.31 – Manufacturing Cost Comparison of different Processes ........................68
Table 5.32 – Machining Time Comparison for different electrodes at various settings
..............................................................................................................................69
Table 5.33 – MRR Comparison for different electrodes at various settings ...............71
Table 5.34 – MRR Comparison for different electrodes at various settings for research
by Leu, Yang and Yao [15]..................................................................................72
Table 5.35 – TWR Comparison for different electrodes at various settings ...............73
Table 5.36 – TWR Comparison for different electrodes at various settings for research
by Leu, Yang and Yao [15]..................................................................................74
xv
PUBLICATIONS
• Ricky Blom, Prasad KDV Yarlagadda and R. M. Iyer, “Evaluation of Rapid
Tooling for Electric Discharge Machining Using Electroforming and Spray
Metal Deposition Techniques”, Proc. of International Conference on
Manufacturing and Management 2004, India, 8-10 December 2004 [In Press].
1
1.0 INTRODUCTION
To compete in today’s industry environment, companies must keep up with the
leading technologies and processes and also push the boundaries and develop new and
improved products and processes. The Manufacturing Industry is an area where time,
efficiency and accuracy are the major driving forces behind innovation and research.
The most competitive companies are those who continually reduce process times,
increase efficiency and improve accuracy. Rapid Prototyping and Tooling is an area
that has and is continuing to reduce production time and increase efficiency and
accuracy in developing and manufacturing prototypes compared to traditional
prototype manufacture.
The main function of Rapid Prototyping (RP) is to give the manufacturing the needed
confidence to go on to tooling and mass manufacture of the product they have
designed. Once the product has met the design criteria through RP it is then needed to
meet the functional criteria and that is where Rapid Prototyping has developed and
evolved into Rapid Tooling. RP is an extremely useful process but it cannot always
provide the manufacturer with a functional prototype in the material of choice.
Rapid Tooling can provide this solution giving the manufacturer a functional
prototype in the material of choice and that allows functional testing to be done on the
product. The use of Rapid Tooling means a reduction in the time-to-market for a
product and also better testing to meet functional criteria. Rapid Tooling is also
useful in helping start production and getting the product into the market, while the
more expensive and durable traditional tool is being produced for the mass
manufacture of the product. Therefore the competition lies in researching possible
ways to increase the effectiveness of Rapid Tooling and reducing the time and cost of
getting the customers product to market.
Electro-Discharge Machining (EDM) is a manufacturing process that has been
affected by developments in Rapid Prototyping and Tooling. EDM is commonly used
by toolmakers for complex injection moulds, punch dies and cavities made from
hardened tool steels. EDM is ideal for materials and complex shapes that traditional
machining processes are unable to perform.
2
In die and mould production, the EDM cycle can account for 25 to 40% of the tool
room lead-time [1, 2]. The electrode production represents over 50% of the cost and
time of an EDM operation [2]. The goal is to reduce the time and cost of the EDM
cycle and to do this, alternate methods of electrode production is a key area of
research.
Since conception EDM electrodes have been manufactured from solid conductive
metals including copper and tungsten, and also from non-metals mainly graphite.
Using traditional machining operations in producing complex electrodes from solid
copper or graphite may require the production of several smaller electrodes and
joining them together, or running several machining cycles to get the required cavity
or shape. Therefore increasing the complexity of the electrode increases the electrode
production time and also increases the machining time if several machining cycles are
required. Investigation into alternate methods of electrode production is required to
reduce cost and time.
To gain a good comparison of the various electrode manufacturing methods, the
experiments include the use of Electroformed Copper, Copper Spray-deposition and
Traditional Solid Machined Copper Electrodes tested under several machining
conditions.
Electroforming is a process that can be controlled to a high degree and can operate
with precision and reliability. Electroforming can be employed to produce electrodes
with complex shapes that in the past would require the use of several conventional
techniques that might include machining, pressing and welding to manufacture a
similar electrode.
The other manufacturing process used in attempts to produce copper electrodes is
Spray Deposition or Spray Metal Deposition as it is also named. Spray metal
deposition has been used to produce moulds for many different moulding processes.
It is possible for the moulds to be manufactured quickly and inexpensively for those
processes [4-9]. As a different rapid prototyping technology and quick production
technology, spray metal tooling is used in a flexible system for producing small
3
numbers of parts. Spray metal deposition is normally used to produce moulds but in
this project it is used to spray into a mould to produce the electrode shells.
When comparing the different electrode manufacturing methods, the machining
conditions include a roughing setting, semi-roughing setting and a finishing setting.
The performance of the EDM process is measured with respect to machining rate or
Material Removal Rate (MRR), electrode wear (TWR), and surface finish of the work
piece (Ra).
The design of the electrodes evolved from previous research in the design and use of
electroformed electrodes. The tool used by Subramanian [3] was found to produce
excess wear on the protruding surfaces and very little wear on the cavities. Therefore
it was decided to do the tests using separate portions of similar design. The tools
developed include a simple conical shape, a triangular protrusion and a more complex
shape that would be almost impossible to machine a similar cavity. The simple and
complex designs are used to compare the various manufacturing methods.
1.1 AIMS AND OBJECTIVES
In the proposed research an attempt will be made to investigate the following:
(a) Testing the viability of electroformed copper electrodes for EDM by
conducting electrode wear studies,
(b) Testing the performance of an electroformed copper electrode in comparison
to a machined copper electrode, based on tool wear and economy of tool
manufacture,
(c) Study the effect of texture of the EDM tool on the work piece material, and
(d) Developing Rapid Tooling for EDM and injection moulding by using Spray
Metal Deposition technique [18].
1.2 METHODOLOGIES
This project involves the following steps:
• Development of CAD models of Electrodes
• Rapid prototyping and tooling to produce electrode master patterns,
4
• Electroforming negative tool to produce copper shells for electrodes, and
backfilling to give the shell support,
• Machining of Solid Copper Electrodes for comparison to alternatively
produced electrodes,
• Production of Spray-metal copper shells for electrodes,
• Testing Electrodes comparing Material Removal Rate (MRR), Tool Wear Rate
(TWR) and Surface finish for the different production methods,
• And evaluating results and developing conclusions.
The thesis includes a literature review in Chapter 2 where the technologies and
processes involved in the research are documented, followed by the outline of the
Experimental Design and Procedure in Chapters 3 and 4 used to collect the required
information and data for analysis. Chapter 5 gives the analysis and description of the
information and data collected during the experiments. Comments are made on the
comparison of the performance of the different electrode manufacturing methods and
machine settings. The conclusions are then summarised in Chapter 6.
5
2.0 LITERATURE REVIEW AND BACKGROUND
The tremendous advancements in EDM technology have been achieved for more than
50 years through the collective efforts of many dedicated engineers from some of the
worlds leading institutions and research centres. The research fields mainly cover
EDM control systems and EDM technology. EDM control system includes the servo
control unit and the parameters that control the system. EDM technology covers the
machine abilities and electrode research.
2.1 RAPID PROTOTYPING AND TOOLING
Rapid Prototyping (RP) and tooling is a continuation from three-dimensional CAD
modelling. RP uses the CAD data to produce layer information that is fed into RP
machines to produce a three dimensional solid model from a chosen process and
material. Common RP processes include Stereolithography (SL), Selective Laser
Sintering (SLS), Laminated Object Manufacturing (LOM) and Fused Deposition
Modelling (FDM). The majority of RP processes involve the conversion of the CAD
data into cross-sectional information and the model is built layer-by-layer.
In the production of EDM electrodes many RP processes have been previously used.
The most promising process involves the use of stereolithography and producing
models as either positive or negative master patterns. Stereolithography (SL) uses
information from a computer generated three-dimensional model to produce a solid
three-dimensional model from various types of laser-curing polymer resins. The
Stereolithography Apparatus builds the three-dimensional solid model layer by layer.
The computer file is broken down to layers and the SLA reproduces the layer on the
surface of the resin. The part is then lowered by the relative layer thickness, and the
process is repeated until the completed model is produced. The Stereolithography
Apparatus used is developed and marketed by 3D Systems Inc, Valencia, California,
USA. The machines produce models with high detail and accuracy and have the
ability to produce multiple parts simultaneously.
Using the positive master pattern is termed as “Direct Electrode Manufacture” in that
the SL pattern is plated with a conductive material and used as the electrode.
6
Alternatively, using the SL pattern as a negative and removing the plated shell is
termed as “Indirect Electrode Manufacture”.
Research in the area of Direct Electrode Manufacturing process includes work from
Arthur et al. [10-14] and Leu et al. [15]. Results using the direct manufacturing
method have shown advantages in that the electrodes are comparable to traditional
solid electrodes in finishing, semi-roughing and roughing machine settings and
electrode production time is reduced as large quantities of electrodes can be produced
simultaneously. The results also concluded disadvantages including the possibility of
non-uniform distribution of electrodeposited material resulting in unknown plating
thickness, EDM machining time is quite high, the SL master pattern is sacrificial and
the electrodes are prone to premature failure if the plating thickness is less than 180
μm.
Alternatively the area of Indirect Electrode Manufacture has been researched and
developed by Jensen and Hovtun [16], Rennie et al. [17] and Yarlagadda et al. [3, 18,
19]. Advantages for using indirect electrode manufacture include relatively low
manufacturing cost, multiple electrodes can be produced simultaneously, the master
pattern can be reused multiple times and the electrodes can be manufactured to high
accuracy and quality. Jensen and Hovtun were also able to show that the performance
is comparable to solid electrodes.
Jensen and Hovtun [16] found disadvantages that include unacceptably high wear
rate, poor accuracy, long process time and internal details can be problematic. Rennie
et al. [17] provided similar disadvantages in that narrow internal cavities are not
plated to the same thickness as external features and failure still occurs with excess
wear and uneven material distribution. Yarlagadda et al. indicated that different
sections of the tool performed more work than other sections, triangular protrusions
had split and tool failure occurred and course machining can deform the tool.
7
2.2 ELECTROFORMING
Electroforming uses electro-deposition of a metallic coating to a mould to produce a
negative copy, which is a hollow shell that is removed from the pattern as the finished
product, or the metallic coating is added to the pattern to produce a platted positive
product on the surface of the pattern. The process is shown in Figure 2.1.
First a mould is produced from the master pattern to be copied. The mould may consist
of a non-metallic substance or sometimes a low-melting-point alloy. A suitable
substance (silicon tooling) used for the production of the mould and plastics, in
particular, have the advantage of producing moulds that have a long service life - i.e.,
can be reused a large number of times. Moulds may comprise one, two or three parts,
depending on the complexity and shape of the model.
For a non-conductive mould the surface of the mould is coated with an electrically
conductive material to allow the electrical circuit to flow. The preferred method is a
fine film of silver sprayed to the surface, other methods include brushed fine graphite
powder or a metallic powder suspended in a thin lacquer.
Using direct current and the principle of electrolysis electro-deposition of metallic
coatings are done in an acid or alkaline salt solution containing the metal to be
deposited. The mould becomes the cathode when connected to the negative pole and
the anode or positive pole is usually made from the metal being deposited. The anode
is gradually consumed during the process. Various auxiliary techniques are applied -
such as the use of internal anodes, masking, etc. - to ensure that a uniform and smooth
metallic coating is formed. By the addition of special substances it is possible to
enhance the smoothness, fineness and lustre of the coating. When a coating of the
desired thickness has been attained, the shell is rinsed, removed from the mould and, if
necessary, given a finishing treatment. Next, the shell may be given backing or filling
of low-melting-point alloy, or some other material, to strengthen it. [20]
8
Figure 2.1 – Electroforming Process
Electroforming is used for a variety of purposes: e.g., making copies of archaeological
or art objects, printing plates, metal discs in the manufacture of phonograph records,
embossing dies, templates, molds for casting, and many object used in mechanical and
electrical engineering. [20]
8) Backfilling the copper shell with aluminium filled epoxy for
extra strength and support
9) Trimming excess materials to finish the copper
electroformed electrode
1) Producing a master pattern in a SLA resin
2) Making a Silicon Mould of the master pattern
3) Removing master pattern from the silicon mould
4) Applying a conductive coating to the mould
Conductive coating
7) Separating the copper shell from the mould
6) Copper electroformed shell in the silicon mould
Copper plating
5) Copper electroforming (electroplating) the mould in an electrolytic cell
9
2.3 SPRAY DEPOSITION
Spray deposition is a process also known as spray-metal deposition, plasma spray
deposition, plasma spraying and plasma deposition. Research in recent years has
shown advances in the use of spray metal and the resulting properties [4-9].
Spray metal deposition involves spraying atomised molten metal on to a pattern to
produce a copy of the surface required as shown in Figure 2.2. The process produces
a shell on the surface of the pattern that is usually removed and back filled to provide
a low cost alternative to producing a solid metal model. The moulds can be made cost
effectively from wood, metal, plastic, ceramic or even leather. These moulds can
become very inexpensive due to the fact that they can be used more than once.
Figure 2.2 – Spray Metal Deposition Process
Pattern
Arc Gun Air Flow
Wire material supply
Arc Region
Deposit
Spray
10
The benefits of Spray Metal Tooling are that it cost 75% less and moulds can be made
in 1/5 of the time. There are various applications in which spray metal tooling is
used:
• Prototype Injection Moulds
• Polyurethane Tooling
• Structural Foam
• Thermoform Tooling
• Blow Moulds
• I.S.P. (instant set polymers)
• Spray Metal Tooling can be used to reduce cost of prototype moulds for;
o Evaluating Injection Moulding Compounds
o Make Custom Trade Show Samples
o Test Physical Characteristics of Moulded Products
o Develop Spray Masks From Moulded parts
o Determine if Shrink Fixtures are Necessary
2.4 EDM
The Electro-Discharge Machine, shown in Figure 2.3, used in the project is the Sodick
Mould-Maker 3 NF40 situated at QMI Solutions in Brisbane.
11
Figure 2.3 – Sodick Mould-Maker 3 NF40
The EDM system consists of a shaped tool (electrode) and the work piece, connected
to a DC power supply and placed in a dielectric fluid. When the potential difference
between the tool and the work piece is sufficiently high, a transient spark discharges
through the fluid and removes a small amount of metal from the surface of the work
piece.
The amount of metal removal rate, surface finish and tool wear are dependent on the
voltage, current and frequency of sparks. Increase in voltage and current results in an
increase in material removal rate and surface roughness.
Due to the machining process occurring without any machining forces, EDM is the
ideal machining process for very fine detailed machining to be done. EDM allows the
steel to be hardened prior to machining to remove the possibility of distortion after
machining.
12
2.5 LITERATURE REVIEW
Research groups have been researching into many areas of Rapid Prototyping and
Tooling. Areas of Rapid Tooling that research has been conducted and is continuing
in include forming tools[21], stereolithography injection mould tools[22, 23], Roto-
tools for casting[24] and polymer infiltration for rapid tools[25]. These areas in rapid
tooling show that there is still a large scope for potential research to improve
traditional and non-traditional tooling. Harris et al. [22, 23] indicates that production
of low volume of parts can be done in much less time and lower costs using the rapid
tooling technologies. Noguchi and Nakagawa [21] have shown that combining RP
processes (SLA and Sintering) provides a useable method of producing metallic rapid
forming tools. Chan et al. [24] provide a proven case for the introduction of rapid
tooling into a traditionally labour intensive and expensive process.
Areas of Rapid Prototyping have been more extensively investigated and researched.
RP covers areas like Laminated Object Manufacture (LOM), Stereolithography
(SLA), and Selective Laser Sintering (SLS). These RP processes are often used as the
initial steps to lead in to Rapid Tooling. Mueller and Kochan [26] have researched
and shown that LOM provides a cheap and effective option as the initial steps for
foundry casting patterns. Extensive use of SLA has been used in the initial steps of
prototyping and manufacture in the areas of injection mould tooling [22, 23, 27], sheet
metal drawing [28], precision forming tools [21], and EDM tooling [3, 10, 11, 14, 15,
18, 19, 29, 30].
“EDM has the advantage of allowing tool steel to be treated to full hardness before
machining, avoiding problems of dimensional variability which are characteristic of
post treatment”[14]. EDM (Electric Discharge Machining) or spark erosion is a non-
traditional machining process used on hardened tool steels when complex and detailed
surfaces are required. In die and mould production, the EDM cycle can account for
25 to 40% of the tool room lead-time [1, 2]. The electrode production represents over
50% of the cost and time of an EDM operation [2]. In today’s manufacturing
environment cost reduction is a main goal, and a great emphasis is placed on the
reduction of time to complete tasks.
13
Decreasing time and improving efficiency of processes is the main focus of many
researchers. Advancements in Rapid Prototyping have allowed for great time saving
in current processes. Rapid Prototyping (RP) and associated techniques like Rapid
Tooling have played a major role in research of cost and time reduction. Rapid
Tooling technologies offer an alternative method of production the promises to
drastically reduce the time involved in design and manufacture of tools [1-3, 10-12,
14-19, 21-25, 29-34]. Within RP, Stereolithography is one of the main methods used
in producing tools. RP is now considered to have a vital role in product development,
cost reduction and time saving [31].
The conventional methods of producing electrodes include stamping, coining,
grinding, extrusion/drawing, turning and milling from materials including copper,
brass, steel and graphite. RP Technology can be used directly or indirectly in the
production of EDM electrodes. Main methods of RP electrode manufacture include
sintering [25, 35-37], electroforming [14, 17-20, 27-29, 38-49], and spray metal
deposition [5, 7, 45]. A facility to sinter metal powder wasn’t available for the
research so electroforming and spray metal deposition was used.
The direct method uses a manufactured model as the electrode or a model that has
been coated by deposition or sheet formed. The direct method has been previously
carried out using the following three approaches: Electrically Conductive Plastic
[32](doesn’t have sufficient electrical conductivity at present); Metal Powder
Impregnated SL Resin Substrate [16, 32] (dismissed due to the inability to cure the
composite resin); Application Of Coatings To Substrates (Various routes from SL
model through metallising and coating to EDM electrode have been identified and
show potential to be viable)[10-12, 15].
The indirect method of electrode manufacture involves the manufacture of a negative
mould in which a shell is produced using material deposition or sheet deformation.
The shell is then backed with a suitable resin or low melt alloy [14]. The following
techniques have been used: Coated Electrodes from Negative Pattern (the negative
pattern is used with electroforming, galvanic plating and spray metal. All have shown
promise except spray metal has poor efficiency due to porosity) [1, 14, 16, 32]; Tartan
14
Tooling and Rotational Copper Casting (Has promising results with electrodes in
copper/tungsten claiming better wear rates than graphite) [33]
Experiments using the direct manufacturing [11, 12, 14, 15, 17] and indirect
manufacturing [16] methods have been attempted to differing degrees of detail.
Arthur et al. [11, 12, 14] mainly researches the electroformed electrodes by optimising
the parameters to get the best MRR, TWR and Ra as possible. Rennie et al. [17]
researched into how the wall thickness of the electroformed shell affects the
machining time.
Leu et al. [15] and Jensen et al. [16] have shown comparisons between non-traditional
electroformed electrodes and traditional machined electrodes. Jensen et al. [16] have
shown a general comparison between electroformed electrodes and machined
electrodes but don’t give much detail into performance of the electrodes. Research by
Leu et al. [15] shows a more details comparison of the different electrodes in terms of
MRR, TWR and Ra but their work is on directly manufactured electrodes. There
appears to be insufficient information in the investigation of the efficiency of indirect
manufactured electrodes (using electroforming and spray metal) compared to
traditional solid electrodes through the manipulation of EDM process parameters.
The lack of information on indirectly manufactured electrodes provided the need to
research further into the non-traditional methods of manufacturing electrodes. There
was also a lack of research into using complex shaped electrodes manufactured in
methods other than the traditional machining.
The previous work carried out that lead into this proposed project includes work done
by Ang in 1998 [30], Hung in 1999 [29] and Yarlagadda, et al. in 1999 [19]. Ang
applied Rapid Tooling techniques to produce electroformed electrodes that were used
in experiments to replace traditional machining with non-traditional machining EDM.
Experimental results showed the potential of the electroformed electrodes in
comparison to solid copper electrodes, but inadequate flushing lead to the failure of
the electrodes.
15
Hung [29] performed experiments based on the work of Ang [30] and concluded that
the electroformed electrodes performance was based on the shell thickness. A shell
thickness less than 2mm couldn’t withstand long process times of EDM. Yarlagadda
et al. [18, 19] continued research into the electroformed copper electrodes. The focus
was on using stereolithography rapid prototyping to produce the master patterns and
vacuum casting to produce a negative pattern. The negative pattern was used in the
electroforming process to produce the copper shells. The electroformed copper shells
were backed with aluminium epoxy. Their experiments proved the potential for
applications of electroformed electrodes to EDM. Those experiments led to this
proposed research.
16
3.0 EXPERIMENTAL DESIGN
The experiments in this research are based on a similar procedure to Leu et al. - “A
Feasibility Study of EDM Tooling Using Metalized Stereolithography Models” [15].
The procedure allows an indication of the difference in the performance of different
manufacturing methods. Leu et al. [15] provided a comparison between
electroformed copper electrodes and traditional solid electrodes by running
experiments at three different machine settings for a set time of ten minutes. There
were a total of eight experiments per electrode type at each machine setting.
EDM performance is dictated by the machine parameters and the optimisation of
those parameters has been the basis of research by the majority of research groups in
the field of EDM. Many researches have used methods such as neural networks [50-
54] and Taguchi method [55-57] to optimise performance characteristics and machine
parameters.
Due to time and budget restrictions the number of experiments determined the type of
analysis that could be done. The Taguchi method and neural network experiments
require a large number of experiments to prove the methods and the budget didn’t
allow that size research. Leu et al. [15] completed eight experiments per machine
setting for each electrode type and to get results that are comparable, within the
budget, only two experiments for each machine setting and electrode type were
conducted.
A comparison of the three electrodes (solid copper, electroformed copper and spray
metal copper) will be made using the same machining conditions and measuring the
performance attributes. The performance attributes measured include material
removal rate (MRR), tool wear ratio (TWR) and surface roughness (Ra).
The electrodes will be tested under three machining conditions and measured to
compare the performance attributes. The machining conditions include a roughing
cut, semi-roughing cut and a finishing cut. Using the same machine parameters for all
three electrodes will allow a good comparison to be made.
17
Using additional test experiments it was determined that using standard preset
machine settings for the three different cuts would be the best way to get comparable
results from the different electrodes at the three different cut settings. The codes
chosen for the machine settings are - C110 – Finishing,
C140 – Semi-roughing,
C170 – Roughing
The machine settings for cutting steel using copper electrodes range from C100 to
C190 when aiming for minimal wear to the electrodes. C110 setting was chosen for a
finishing cut because C100 was extremely fine and the machining time was too high
for the timeframe of these experiments. C170 setting was used because the C180 and
C190 settings were too aggressive for the electroformed electrodes and the C170
setting allowed the test electroformed electrodes to actually machine the test pieces.
The C140 setting was chosen on the fact that it evenly divided the other two settings.
The settings for the three different experiments involve the following parameter
settings –
Table 3.1 – Machine Settings or Finishing, Semi-Roughing and Roughing Cuts
Machine Setting
Discharge Pulse Duration
ON
Quiescent Pulse Duration
OFF
Quiescent Time MA
Peak Current
IP Servo Voltage
SV Polarity
PL C110 012 012 01 002.0 03 +
C140 016 016 01 005.0 05 +
C170 019 019 01 010.0 05 +
The values given are not actual values. They are machine setting numbers for the
scale on the machine. The actual values for the machine settings are as follows:
Table 3.2 – Actual Settings or Finishing, Semi-Roughing and Roughing Cuts
Machine Setting
Discharge
Pulse Duration
ON
Quiescent
Pulse Duration
OFF
Quiescent
Time
MA Peak Current
IP Servo Voltage
SV Polarity
PL C110 80μsec 20μsec X2 2A 35V +
C140 180μsec 20μsec X2 5A 60V +
C170 350μsec 30μsec X2 10A 60V +
18
To restrict the experimental machining time the cut depth will be reduced according to
the cut type. The roughing cut will make a cut of approximately 1mm, the semi-
roughing cut will be 1mm and the finishing cut will be 0.5mm. The machining time is
measured on the EDM computer control unit and it measures to an accuracy of
seconds.
The electrodes and work-pieces will be measured before and after to determine the
MRR, TWR and Ra. The MRR can be measured using one of the following
mathematical equations –
( ) ( ) ( )( )min
min/2
3
CutofTimemmCutofDepthmmAreaElectrodemmMRR ×
= (1a)
( ) ( )( )min
min/CutofTime
gMassElectrodegMRR = (1b)
MRR can be measured by the change in weight or change in volume of the electrode
and the work-piece. Determining MMR was measured in grams per minute as it was
more accurate to measure change in mass than change in volume with the equipment
that was available at the time of the experiments.
The mass of the electrodes and work pieces was measured on standard electronic
scales which measures masses from 0 to 100g to an accuracy of 0.001g increments,
masses from 100 to 500g to 0.01g increments and above 500g to 0.1g increments.
The TWR is measured by –
( ) ( )( ) 100% 3
3
×ΔΔ
=mmVolumemmVolumeTWR workpiece
Electrode
(2)
The measurements can be made by weight and also the use of a coordinate measuring
machine (CMM). CMM was chosen because of the accuracy attainable and also the
availability of the machine itself. The CMM has the accuracy to measure down to
19
0.001mm in horizontal axis and vertical axis. The CMM is used to measure the
vertical height and change of height at preset coordinates in the horizontal plane (x
axis and y axis).
Using the CMM, a grid is used to measure preset points before and after experiments.
The difference is used to determine the amount of wear or material removed from
different sections and features of the electrodes and test pieces.
The Ra is measured using a machine such as a Taylor Hobson Surtronic instrument.
Several measurements are made on each electrode and test piece to give and average
roughness of the whole machined surfaces. The surface roughness is measured to the
very fine increments of 0.01μm. The measuring probe scans a 4mm section of the
surface and then determines the average surface roughness (Ra).
Measurements for the experiments were made on equipment available but the
measurements such as the masses, volumes and heights could have been measured to
greater accuracy with more advanced machines. The volume is one method that was
unable to be used but if a three dimensional scanner was available it would have been
possible to measure the change of volume.
20
4.0 EXPERIMENTAL PROCEDURE
The experimental results compare the performance of the different electrode
manufacturing methods at the three different machine settings. The aim is to compare
the electrode performance at different workloads on the electrode from roughing cuts,
semi-roughing and finishing cuts. The three settings cut at different speeds so the
depth of cut for the finishing cut was reduced. This was to prevent the machining time
from climbing too high.
The selection of electrode shapes (Figure 4.1) was to help compare different areas of
tool manufacture and performance. Tool shapes were developed from previous
research carried out by Subramanian [3], who showed that trying to test the different
geometries in one tool was not as helpful so the shapes were developed separately.
The three shapes developed highlighted the tools machining performance and the
ability to cope with a broad range of tool features and shapes. The new tool shapes
include smooth curved surfaces, sharp corners, low draft angles and complex deep
holes and this differs from previous work carried out by Leu et al. [15] because their
research was done using very simple shaped machining into a flat work piece. The
complex shapes were also used to get an indication of the limitations of the
Electroforming and Spray Metal processes to produce the various shapes and then
their suitability to be used in the EDM process.
The electrodes were all set up in the same conditions and the similar shapes made the
same cuts at the same settings. The depth of cut is measured from the top surface of
the work piece and the experiments begin with the depth of the hole in the near net
casting. The first four experiments are 1mm cut added to the previous measurement
and the final two experiments are 0.5mm extra.
21
Figure 4.1 – SLA Electrode Master Patterns
The electrodes and work pieces were measured before and after each experiment to
determine the MMR, TWR and Ra.
Using the CMM and a 2mm grid as shown in Figure 4.2, heights were measured to
determine the material removed in the machining process.
Figure 4.2 – Electrode grid measurements
2mm
22
The coordinates measured were tabulated as in Table 4.1 and graphed as shown in
Figures 4.3 (before experiment) and Figure 4.4 (after experiment) to give a visual
representation of the measurements.
Table 4.1 – CMM Coordinate measurements of the electrode height
Y x
16.000 14.000 12.000 10.000 8.000 6.000 4.000 2.000 0.000 -2.000 -4.000 -6.000 -8.000 -10.000 -12.000
16.000 0.025 0.017 0.015 0.010 0.007 0.004 0.000 -0.004 -0.002 -0.003 -0.006 -0.007 -0.005 -0.008
14.000 0.020 0.019 0.011 0.010 0.006 0.045 -0.027 0.018 0.018 0.028 -0.010 0.019 -0.007 -0.011 -0.009
12.000 0.024 0.018 0.015 0.018 0.025 0.057 0.016 -0.003 0.002 0.008 -0.025 0.000 -0.010 -0.008 -0.010
10.000 0.025 0.019 0.019 0.074 0.021 0.030 -0.056 -0.046 -0.109 -0.035 -0.089 -0.001 -0.010 0.024 -0.011
8.000 0.021 0.017 0.034 0.065 0.001 -0.020 -0.102 -0.096 -0.134 -0.090 -0.127 -0.017 -0.012 0.013 0.099
6.000 0.023 0.052 0.043 0.009 -0.039 -0.080 -0.086 -0.062 0.000 0.018 -0.075 -0.061 -0.015 0.007 -0.003
4.000 0.022 0.049 0.057 -0.007 -0.007 -0.029 0.060 0.143 0.152 0.166 0.154 0.024 0.016 0.031 0.017
2.000 0.022 0.045 0.000 0.007 0.001 0.070 0.143 0.159 0.129 0.155 0.140 0.122 0.011 0.052 0.003
0.000 0.021 0.037 0.009 0.002 0.015 0.070 0.156 0.137 0.136 0.153 0.153 0.155 0.025 0.024 0.003
-2.000 0.021 0.026 0.016 -0.030 -0.044 0.027 0.186 0.146 0.138 0.138 0.151 0.141 0.032 0.001 -0.008
-4.000 0.018 0.036 0.003 -0.026 -0.066 -0.044 0.084 0.133 0.160 0.148 0.209 0.102 0.023 -0.018 -0.038
-6.000 0.015 0.023 0.025 -0.030 -0.021 -0.124 -0.055 -0.050 0.073 0.035 0.058 -0.011 -0.036 -0.070 -0.036
-8.000 0.012 0.004 0.043 0.000 -0.025 -0.083 -0.089 -0.130 -0.122 -0.115 -0.076 -0.077 -0.045 -0.064 -0.051
-10.000 0.008 0.004 0.013 0.032 -0.033 -0.047 -0.071 -0.060 -0.069 -0.014 -0.047 -0.048 -0.065 -0.023
-12.000 0.007 0.000 -0.002 -0.006 0.051 0.014 0.057 -0.041 -0.001 -0.035 0.023 -0.061 -0.047 -0.029 -0.024
-14.000 0.006 0.000 -0.005 -0.011 -0.016 -0.097 0.032 -0.069 0.015 -0.045 0.034 -0.116 -0.019 -0.023 -0.020
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-5.000
0.000
5.000
10.000
15.000
20.000
25.000
30.000
Height (mm)
Length (mm)
Width (mm)
Electroformed Electrode EC1a
Figure 4.3 - Electrode Measurements before Experiment
23
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-5.000
0.000
5.000
10.000
15.000
20.000
25.000
30.000
Height (mm)
Length (mm)
Width (mm)
Electroformed Electrode EC1b
Figure 4.4 - Electrode Measurements after Experiment
The used measurements are subtracted from the unused measurements to give the
result shown in Figure 4.5. The graph gives an indication of the amount of material
removed and the areas of most material removed. These graphs are used to give a
visual comparison between the wear experienced by the different manufacturing
methods of the electrodes.
24
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
0.200
0.250
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC1a-b
Figure 4.5 - Material removed from the electrode during the experiment.
The results in Table 4.2 show the masses before and after the experiments and the
calculations performed to determine the MRR using equation 1b (p18) and TWR
using equation 2 (p18). When calculating the MRR and TWR the results needed to
indicate if there was or wasn’t any significant difference throughout the corresponding
experiments.
Table 4.2 – Mass measurements and calculations taken from experiments
machine
time (min) MRR
(g/min) TWR (%)
Electroformed Base A B A-B A-B 1 63.616 63.423 0.193 46.80 0.004 1.804 2 80.044 79.696 0.348 49.53 0.007 2.122 3 71.027 70.851 0.176 89.83 0.002 1.375 4 58.865 58.359 0.506 211.33 0.002 2.410 5 59.02 58.185 0.835 990.03 0.001 23.857 6 75.63 74.55 1.08 1947.75 0.001 12.000
The Taylor Hobson Surtronic instrument was used to measure the Ra of the electrodes
and the work pieces. The measurements were taken on all sides and accessible
surfaces of the used electrodes and test pieces. Results were tabulated as shown in
25
Table 4.3. Because the results were only compared using the Ra value the Rq, Rt and
Rsk values were not used.
Table 4.3 – Measurements of Ra from the Taylor Hobson Surtronic
Experiment 1 Ra mm Rq mm Rt mm Rsk FC2b 1 6.82 8.62 47 0.06 2 6.27 8.19 45.6 0.22 3 6.68 8.12 41.4 0.37 4 7.89 10.41 58.4 0.57 Average 27.66
26
5.0 EXPERIMENTAL RESULTS
A total of six experiments were carried out. Due to manufacturing costs two sets of
three solid copper electrodes, six sets of three electroformed electrodes and two sets
of three spray metal electrodes were produced. As explained later in this chapter the
spray metal electrodes didn’t work as expected. Due to the porosity and uneven
thickness in the spray metal electrode shells the backing material penetrated and made
the electrodes unusable. Therefore the performance of the spray metal electrodes
failed before making it to the EDM stage.
5.1 EXPERIMENT 1
A roughing cut was used in the first set of experiments with the machine set on a
standard machine setting of C170. This produced high MRR and Ra with low
machining time and TWR.
The machine and actual settings were as follows:
Nominal Actual
Machine Setting: C170 C170
Discharge Pulse Duration (ON): 019 350μsec
Quiescent Pulse Duration (OFF): 019 30μsec
Quiescent Time (MA): 01 X2
Peak Current (IP): 010.0 10A
Servo Voltage (SV): 05 60V
Polarity (PL): + +
The following is the depth of cut for the first set of experiments:
Cone Electrode – 28mm
Triangle Electrode – 26mm
Base Electrode – 19mm
27
5.1.1 Solid Electrodes compared to Electroformed Electrodes
The performance of the electrodes can be compared in several ways. Tool wear shows
the durability of the electrode itself. Results of experiment 1 show that the tool wear
is greater in the electroformed electrodes. The following Figures 5.1(a) and 5.1(b)
have been given the same measurement scales to give a true indication of the
comparison in wear. Figure 5.1(a) shows that solid electrode has very little wear and
any wear that has occurred is less than 0.05mm. The electroformed electrode hasn’t
performed as well as the solid electrode and this is emphasised in Figure 5.1(b) by the
wear being greater than 1mm on the sharp corners and over 0.1mm around the edges.
Figures 5.1(a) and 5.1(b) are shown as an example of the difference in wear and in the
following experiments the figures will be supplied in Appendix A.
One of the problems encountered when using the electroformed electrodes was the
ability to damage the electrode when beginning the experiment. The expanded view in
Figure 5.2 shows the damage that can happen. The damage was cause by a lack of
conduction through the electrode holder and the electrode. During the setup the
electrode came in contact with the work piece and did not produce a circuit to register
in the z axis.
Figure 5.2 also shows the wear that occurs on the sharp corners of the electrode. The
green line gives an estimate on the shape of the original electrode. There is very little
taper on the walls of the base electrode and that resulted in very little work being
performed by the vertical walls of the electrode.
28
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SB2 a-b
Figure 5.1(a) – Base Electrode Wear Experiment 1 - Solid Electrode
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EB1
Figure 5.1(b) – Base Electrode Wear Experiment 1 - Electroformed Electrode
29
Figure 5.2 – Damage and excessive wear of Electroformed Base Electrode (EB1)
The cone electrodes show similar characteristics as the base electrodes in that the solid
electrode (Figure A.1) has less than 0.1mm wear and the electroformed electrode
(Figure A.2) shows greater wear of over 0.1mm on the higher sections. The negative
wear on the electroformed electrodes was caused by the deformation of the electrode.
Heat from the EDM process builds up in the copper and is partially insulated by the
back filled material therefore expanding the copper. Increased localised wear on the
point of the electrode is also caused by the extra work performed by the tip. The work
piece is a near net casting and the cavity has more material to remove at the base of the
cavity until the hole is identical to the electrode shape. The following experiments
experienced a more even work rate.
The CMM results for the solid cone electrode shows a negative wear in a small area
near the front left of Figure A.1. The negative wear is the result of a carbon build up
from an inclusion in the work piece casting. Figure 5.3 shows the inclusion that
appeared after the first experiment and the black carbon build up on the electrode.
The inclusion didn’t appear to affect the MRR.
30
(a) Work piece (b) Electrode
Figure 5.3 – Casting Inclusion and Electrode Wear
Triangle electrodes gave a very good indication of excessive wear when the electrode
is needed to machine larger amounts of material. As shown in Figure A.3 the solid
electrode has lower wear than the electroformed electrode. Figure A.3 has two points
of very high negative wear. The negative wear is from the CMM trying to measure an
edge of the electrode and not hitting exactly the same points when remeasuring.
Figure A.4 shows negative wear on the large angled surfaces which is caused by
expansion of the copper around the back filled core.
The higher wear along two sides of the electrodes was produced by increased work
rate. The cavity of the near net castings is slightly smaller than the electrodes and any
vertical surfaces will be machined more than the surfaces that are more horizontal.
Figure 5.4 shows the difference in size of the near net casting and the electrodes.
31
Figure 5.4 – Machining of triangle work piece in experiment 1
The solid triangle electrode performed better than the electroformed electrode in terms
of the shape of the machined cut, because the electroformed electrode failed during the
experiment. The sharp corners of the electrode wore through to expose the back filled
core and therefore stopped machining in that small are. Figure 5.5 shows the results of
the failure.
(a) Failed Electroformed Electrode (b) Experiment 1 Work Piece
Figure 5.5 – Failed Electroformed Electrode and Experiment 1 Work Piece
5.1.2 Work pieces machined by different electrodes.
Machining the work pieces in Experiment 1 involved a roughing cut to remove
material fast to be left with the rough shape required. Additional cuts are made to get
to the final shape, depth and finish required. Experiment 1 was set up to make a 1mm
Material Removed
Work Piece
Electrode
32
cut at measured from the base of the existing near net cast hole. Figure A.5 shows that
the original base hole wasn’t uniform in depth and the electrodes were used to
machine holes as even as possible to continue with the experiments. Both electrodes
reached the flange before finishing the cut.
Machining with the solid base electrode (Figure A.5) gave a reasonably even cut to a
depth of 0.5mm around the flange and a little more inside the hole. A few spikes of
over 2mm indicated that some machining was done on the vertical surfaces. An
uneven result was given by the electroformed electrode. Figure A.6 shows that the
flange removed a very uneven amount of material. The electroformed electrodes
could not be guaranteed to be perfectly flat on the flanges and the larger flat surfaces.
Machining with the cone electrodes provided very similar results for both Solid
(Figure A.7) and Electroformed (Figure A.8) Cone Electrodes. As shown in Figure
A.7 the material removed was up to approximately 4.5mm but the point of origin for
the measurements in the centre of the work piece shows a depth of cut close to 1mm.
The extra depth of machining around the centre is due to the near net casting hole
having a reduced taper angle to the electrodes.
Work pieces used for the triangle electrodes gave very similar results when put under
the CMM. Figure A.9 and Figure A.10 show very similar results for the solid and
electroformed electrodes, apart from the failed corners of the electroformed electrode
(Figure 5.5). Both work pieces show that there has been more material removed along
the vertical walls of the holes. The rest of the machined area shows a reasonably even
1mm depth of cut.
Apart from the CMM measurements, change in mass, machining time, material
removal rate (MRR) and tool wear rate (TWR) were also measured and calculated.
The change in mass (Table 5.1) and the machining time (Table 5.2) were used in
equation 1 to determine the MRR (Table 5.3) and also equation 2 to result in TWR
(Table 5.4). The resulting MRR figures indicate that all electrodes performed evenly
at a roughing cut setting.
33
Table 5.1 – Change in Mass for Experiment 1
Change in Mass Grams
Solid Base Electrode 0.1
Electroformed Base Electrode 0.193
Solid Cone Electrode 0.38
Electroformed Cone Electrode 0.123
Solid Triangle Electrode 0.62
Electroformed Triangle Electrode 0.359
Base Work piece (solid) 7.7
Base Work piece (electroformed) 10.7
Cone Work piece (solid) 19.8
Cone Work piece (electroformed) 18.3
Triangle Work piece (solid) 21.9
Triangle Work piece (electroformed) 18.0
Table 5.2 – Machining Time for Experiment 1
Machining Time Minutes
Solid Base Electrode 19.47
Electroformed Base Electrode 46.80
Solid Cone Electrode 85.52
Electroformed Cone Electrode 43.37
Solid Triangle Electrode 58.02
Electroformed Triangle Electrode 50.83
34
Table 5.3 – Material Removal Rate for Experiment 1
Material Removal Rate Grams/Minute
Base Work piece (solid) 0.396
Base Work piece (electroformed) 0.229
Cone Work piece (solid) 0.232
Cone Work piece (electroformed) 0.422
Triangle Work piece (solid) 0.377
Triangle Work piece (electroformed) 0.354
Experiment 1 was used to make a clearing cut on the work pieces to basically set up
the work pieces for the following experiments. To get a more precise indication of the
performance of the electrodes it is recommended that all of the experiments should be
looked at before making conclusions. Table 5.4 shows TWR for Experiment 1 are
very similar showing very small wear on all electrodes.
Table 5.4 – Tool Wear Rate for Experiment 1
Tool Wear Rate Percentage (%)
Solid Base Electrode 1.299
Electroformed Base Electrode 1.084
Solid Cone Electrode 1.919
Electroformed Cone Electrode 0.672
Solid Triangle Electrode 2.831
Electroformed Triangle Electrode 1.994
The final measurement for each experiment is the surface roughness Ra (Table 5.5).
All work pieces measured high in roughness except the base work piece for the
electroformed experiment. The low Ra is a result from a lack of work done by the
vertical walls of the electrode. When measuring the surface roughness, the probe is
only able to measure surfaces accessible from the top of the work piece and therefore
the surfaces measured are the vertical walls. Figure 5.6 shows how the electrode has
not performed much work with the vertical walls. The silver regions are the parts of
35
the electrode that didn’t do any work whereas the black sections are where a spark was
produced leaving a small burn mark.
Table 5.5 – Average Surface Roughness Ra μm, Experiment 1
Ra Average μm
Cone Work piece (electroformed) FC2b 6.92
Cone Work piece (solid) FC3b 7.04
Triangle Work piece (electroformed) FT1b 6.28
Triangle Work piece (solid) FT2b 6.75
Base Work piece (electroformed) FB2b 3.61
Base Work piece (solid) FB1b 5.63
Figure 5.6 – Electroformed Base Electrode for Experiment 1
5.2 EXPERIMENT 2
Experiment 2 was conducted using the same settings as used in experiment 1 which
meant it was another roughing cut. The machine setting remained at C170 but the
depth of cut was set 1mm deeper.
The following is the depth of cut for the second set of experiments:
Cone Electrode – 29mm
Triangle Electrode – 27mm
Base Electrode – 20mm
36
As in experiment 1 the results gave high MRR and Ra with low machining time and
TWR.
5.2.1 Solid Electrodes compared to Electroformed Electrodes
The base electrodes performed very similar to experiment 1 when measured by the
CMM. The solid electrode (Figure A.11) completed the experiment with wear of less
than 0.01mm over the majority of the electrode. Wear of greater than 0.01mm was
measured only in several points on the sharp edges of the electrode. There is
considerably more wear on the electroformed electrode (Figure A.12) compared to the
solid electrode. The wear on the complex shape of the electroformed electrode was
concentrated on the sharp edges and corners and measured over 0.05mm up to
0.35mm which is a similar pattern to experiment 1.
Again the majority of the machining was performed by the horizontal surfaces of the
base electrodes. Figure 5.7 shows the black areas from which sparks were generated
and the silver areas that have not done any machining. As the electrode gets within
the critical distance to the work piece a spark will jump from the electrode to the work
piece removing material from both the electrode and work piece.
Figure 5.7 – Electroformed Base Electrode
Again the wear on the cone electrodes followed the previous experiments in that there
is significantly more wear on the electroformed electrode. Figure A.13 shows that the
majority of wear on the solid electrode is less than 0.05mm compared to Figure A.14
37
showing more than 0.2mm wear on the electroformed electrode. The wear on the solid
electrode is more even than the electroformed electrode. Figure A.14 shows that the
wear is concentrated in the centre of the electrode which is also the highest tip of the
cone electrode.
Although Figure A.14 does not show the damage to the electroformed electrode, there
was a small amount of damage done when setting up for the experiment. A small
indent near the top of the electrode (Figure 5.8) was made in the same way as the
damage on the electroformed base electrode in experiment 1. The problem was
rectified for following experiments with an altered electrode attachment to the EDM.
Figure 5.8 – Electroformed cone electrode – Experiment 2
Electrode wear for the triangle electrodes followed the pattern of the previous
experiments. The solid electrode (Figure A.15) showed the same wear pattern to
experiment 1 and also the problem of the CMM not measuring exactly the same points
as the previous measurements. Apart from the erratic points along the edges of the
graph, the main wear is shown along the centre of the electrode which is the centre
ridge of the electrode.
The electroformed electrode (Figure A.16) showed some wear but there was more
change in measurement due to warping. The CMM measurements showed a lot of
uneven change in the positive and negative. Figure 5.9 shows how uneven the
electrode machined and was worn.
The uneven machining done by the electrode will cause changes to the following
experiments in that the next electrode will be machining an uneven surface.
38
Figure 5.9 – Electroformed triangle electrode – Experiment 2
5.2.2 Work pieces machined by different electrodes
Machining of the base work pieces was much more even over the entire surface.
Figure A.17 and Figure A.18 show that almost the entire surface was machined to a
depth of 1mm. Both electrodes show almost identical machining performance.
Several high points on the graphs are the result of the CMM measuring a point that has
been machined on a vertical surface. The cavity erodes slightly larger and the CMM
probe measures down the inside of the wall of the cavity to give the higher
measurement.
Even machining of approximately 1mm (Figure A.19) was measured across the
machined surface of the work piece machined by the solid electrode. Due to the
damage occurring to the electroformed electrode during setup, the work piece
displayed uneven machining when measured on the CMM (Figure A.20).
Again the solid electrode has machined evenly at 1mm with a small amount of extra
wear down the side of the cavity (Figure A.21). As the electrode machines deeper, the
electrode walls also machine a small amount sideways. The electroformed electrode
machined another 1mm deeper into the work piece however the warping of the
electrode shown previously in Figure A.16 gave uneven machining shown in Figure
A.22.
39
Table 5.6 showed the change in mass of the electrodes and work pieces during
experiment 2. The wear on the electrodes show that the electroformed electrodes
didn’t perform as well as the solid electrodes in that the wear is higher for the
electroformed electrodes in all three electrode shapes. The machining of the work
pieces shows very similar material removal for both solid and electroformed
electrodes. The similarity is true except for the damaged electroformed cone electrode
which had problems during set up.
Machining time shown in Table 5.7 indicates that the time taken to machine the work
pieces is similar for the different electrode types but is very different for the different
shapes of electrodes. The surface area of each electrode has an influence on the
machining time as there is more material removed when there is greater surface area.
Table 5.6 – Change in Mass for Experiment 2
Change in Mass Grams
Solid Base Electrode 0.2
Electroformed Base Electrode 0.348
Solid Cone Electrode 0.05
Electroformed Cone Electrode 0.086
Solid Triangle Electrode 0.02
Electroformed Triangle Electrode 0.359
Base Work piece (solid) 16.4
Base Work piece (electroformed) 16.4
Cone Work piece (solid) 4.3
Cone Work piece (electroformed) 0.8
Triangle Work piece (solid) 6.3
Triangle Work piece (electroformed) 4.0
40
Table 5.7 – Machining Time for Experiment 2
Machining Time Minutes
Solid Base Electrode 39.40
Electroformed Base Electrode 49.53
Solid Cone Electrode 12.53
Electroformed Cone Electrode 8.12
Solid Triangle Electrode 17.15
Electroformed Triangle Electrode 13.23
MRR gives a much more even method of comparing electrode performance. The
MRR for experiment 2 is very similar to experiment 1 machining within 0.2 g/min of
each other. The performance is also very comparable for all of the electrode shapes
and types shown in Table 5.8. As the previous images and measurements have shown,
the electroformed cone electrode gives a false indication of performance because of
the damage done on the electrode.
Table 5.8 – Material Removal Rate for Experiment 2
Material Removal Rate Grams/Minute
Base Work piece (solid) 0.331
Base Work piece (electroformed) 0.416
Cone Work piece (solid) 0.343
Cone Work piece (electroformed) 0.099
Triangle Work piece (solid) 0.367
Triangle Work piece (electroformed) 0.302
TWR again was comparable to experiment 1 except for the damaged electroformed
cone electrode. All acceptable TWR was under 3% for the first 2 experiments (Table
5.4 and Table 5.9).
41
Table 5.9 – Tool Wear Rate for Experiment 2
Tool Wear Rate Percentage (%)
Solid Base Electrode 1.220
Electroformed Base Electrode 2.122
Solid Cone Electrode 1.163
Electroformed Cone Electrode 10.750
Solid Triangle Electrode 0.317
Electroformed Triangle Electrode 1.825
As expected the surface roughness was comparable across all of the work pieces
(Table 5.10). The second experiment was similar to experiment 1 and Ra was at the
high level for a roughing cut. The following experiments are expected to show a
lower Ra for the semi-roughing and the finishing cuts.
Table 5.10 – Average Surface Roughness Ra μm, Experiment 2
Ra Average μm Cone Work piece (electroformed) FC2c 7.09
Cone Work piece (solid) FC3c 8.46
Triangle Work piece (electroformed) FT1c 5.94
Triangle Work piece (solid) FT2c 7.22
Base Work piece (electroformed) FB2c 6.78
Base Work piece (solid) FB1c 6.68
5.3 EXPERIMENT 3
Experiment 3 was the first of two sets of semi-roughing cut experiments. A standard
machine setting of C140 was set for all experiments. This setting produced lower
MRR and Ra with higher machining time but a similar TWR compared to
Experiments 1 and 2. Experiment 3 was another cut of 1mm added to the depth of
experiment 2 which was measured from the top surface of the work piece.
42
The machine and actual settings were as follows:
Nominal Actual
Machine Setting: C140 C140
Discharge Pulse Duration (ON): 016 180μsec
Quiescent Pulse Duration (OFF): 016 20μsec
Quiescent Time (MA): 01 X2
Peak Current (IP): 005.0 5A
Servo Voltage (SV): 05 60V
Polarity (PL): + +
The following is the depth of cut for the third set of experiments:
Cone Electrode – 30mm
Triangle Electrode – 28mm
Base Electrode – 21mm
5.3.1 Solid Electrodes compared to Electroformed Electrodes
Performance of both solid and electroformed base electrodes is very similar. The
majority of wear on both electrodes is less than 0.05mm. There are also only a couple
of points on each electrode that have excessive wear and the high measurements as
seen in the first two experiments. The solid electrode (Figure A.23) gave a similar
performance to experiments 1 and 2 but as expected there is an average of slightly
more wear over the machining surface. On closer inspection of the CMM results of
the electroformed base electrode (Figure A.24), there is a significant amount of
negative wear which gives a false impression that the wear is less than experiments 1
and 2. The negative wear is produced from warping of the electrode during EDM
machining. Both electrodes have shown increased wear compared to the previous
experiments.
Again all of the machining was performed by the horizontal surfaces and the vertical
surfaces are almost untouched. Figure 5.10 again shows the black regions the
performed work and the unused silver areas. The sharp edges were the areas of
concentrated wear.
43
Figure 5.10 – Electroformed Base Electrode – Experiment 3
The cone electrodes (Figure A.25 and Figure A.26) have shown a similar trend to the
base electrodes showing increased wear all over the machining surface. Warping has
also effected the electroformed electrodes measurements giving a significant amount
of negative wear shown in Figure A.26. The wear on the solid electrode has increased
to between 0.05mm and 0.1mm compared to the experiments 1 and 2 where the wear
is less than 0.05mm. Increased wear on the electroformed cone electrode is also a
result of the damage and reduced machining that occurred in experiment 2. Due to the
warping of the electroformed electrodes it is hard to determine the magnitude of extra
wear occurring on the electrode compared to previous experiments. The wear pattern
has changed and it is not concentrated in the centre as in experiments 1 and 2. The
wear shows a more even coverage of the electrode machining surface.
Apart form the erratic measurements made along the edges of the electrode the solid
triangle electrode (Figure A.27) showed a very small amount of wear over the
machining surface of the electrode. The majority of the wear is less than 0.05mm and
this is similar to previous experiments except the wear is more evenly spread over the
electrode. Experiments 1 and 2 have shown increased wear along the ridge if the
triangle electrode compared to Experiment 3. Along with the change in pattern the
overall wear on the electrode is slightly higher in Experiment 3, which follows the
trend of the other experiments in Experiment 3.
44
Even though the electroformed cone electrode has again shown the problem of
warping (Figure A.28), it is following the trend of increased overall wear and the
uneven wear is a result of the previous uneven machining in experiment 2.
5.3.2 Work pieces machined by different electrodes
Machining in experiment 3 showed a similar performance to experiment 2 and the
electrodes performed relatively equal when comparing solid and electroformed.
Figure A.29 shows that the solid electrode machined a very even 1mm of material
from the work piece. The performance of the solid electrode is almost identical as in
experiment 2.
The electroformed electrode didn’t perform as expected and the cut didn’t machine the
full 1mm from the work piece. Figure A.30 shows that the machining depth reached
approximately 0.75mm. The result was affected during the setup of the experiment.
The cutting depth is set by referencing the top of the electrode with the top of the work
piece and setting that plane as zero in the z axis. From the CMM measurements the
electroformed electrode measured a high point. So when the electrode was referenced
against the work piece it was incorrectly zeroed off the highpoint.
The cone work pieces performed similar to previous experiments. The work piece
machined by the solid electrode shows a roughly even machined area (Figure A.31).
The machined area isn’t exactly even because once the EDM reaches the set depth of
cut it will stop machining. And because the setup of the experiment cannot be
guaranteed exactly the same every time the centre of the electrode might not line up
exactly with the centre of the work piece. More accurate experiments could be
performed with greater time allowances and budgets.
Figure A.32 shows the material removed from the work piece by the electroformed
cone electrode. Because of the damaged done to the electrode in the previous
experiment the electrode didn’t remove all of the material it was expected to. The
following experiment removed the additional material and it is shown in the CMM
45
measurements. The uneven machining shows that up to 2.3mm was removed when a
cut of 1mm was set.
The triangle electrodes again show in Figure A.33 that the solid electrode machines a
much more even depth and Figure A.34 shows that the electroformed electrode
machines unevenly because of the warping of the electrodes.
Change in mass (Table 5.11) again basically follows the trend of previous experiments
in that the solid electrodes wear less than the electroformed electrodes. There are a
few slight differences in the trend but the many factors affecting the performance of
the electrode make it very difficult to define the cause. Some of the factors that may
influence the irregularity of the results include electrode warping, flushing, setup and
previous experiments.
Table 5.11 – Change in Mass for Experiment 3
Change in Mass Grams
Solid Base Electrode 0.1
Electroformed Base Electrode 0.176
Solid Cone Electrode 0.05
Electroformed Cone Electrode 0.152
Solid Triangle Electrode 0.16
Electroformed Triangle Electrode 0.117
Base Work piece (solid) 15.3
Base Work piece (electroformed) 12.8
Cone Work piece (solid) 4.2
Cone Work piece (electroformed) 9.0
Triangle Work piece (solid) 7.0
Triangle Work piece (electroformed) 6.7
Machining time (Table 5.12) shows equal times for machining of the different electrode
types for the different electrode shapes. The only major difference is the electroformed
cone electrode. The electroformed electrode removed 9g of material in 77.40 minutes
46
where the solid electrode only removed 4.2g in 46.58 minutes. A better comparison is
given when comparing the MRR in Table 5.13.
Table 5.12 – Machining Time for Experiment 3
Machining Time Minutes
Solid Base Electrode 95.75
Electroformed Base Electrode 89.83
Solid Cone Electrode 46.58
Electroformed Cone Electrode 77.40
Solid Triangle Electrode 49.17
Electroformed Triangle Electrode 46.80
As expected the MRR is reduced compared to the first two experiments. The C140
setting has lowered the MRR to below 0.160 grams per minute (Table 5.13) compared
to the C170 setting where the MRR was above 0.330 grams per minute on average.
Table 5.13 – Material Removal Rate for Experiment 3
Material Removal Rate Grams/Minute
Base Work piece (solid) 0.160
Base Work piece (electroformed) 0.142
Cone Work piece (solid) 0.090
Cone Work piece (electroformed) 0.116
Triangle Work piece (solid) 0.142
Triangle Work piece (electroformed) 0.143
The Tool Wear Rate (Table 5.14) has shown comparable figures to Experiment 1 and
2. There is no significant change between the roughing and semi-roughing cuts.
47
Table 5.14 – Tool Wear Rate for Experiment 3
Tool Wear Rate Percentage (%)
Solid Base Electrode 0.654
Electroformed Base Electrode 1.375
Solid Cone Electrode 1.190
Electroformed Cone Electrode 1.689
Solid Triangle Electrode 2.286
Electroformed Triangle Electrode 1.746
Surface Roughness (Ra) is a measurement that was expected to reduce when changing
the machine setting from C170 to C140. Table 5.15 shows that the Ra for the work
pieces has reduced by approximately 2 μm which is roughly 25% on average.
Table 5.15 – Average Surface Roughness Ra μm, Experiment 3
Ra Average μm Cone Work piece (electroformed) FC2d 5.63
Cone Work piece (solid) FC3d 5.27
Triangle Work piece (electroformed) FT1d 6.11
Triangle Work piece (solid) FT2d 6.03
Base Work piece (electroformed) FB2d 4.34
Base Work piece (solid) FB1d 4.41
5.4 EXPERIMENT 4
Experiment 4 was conducted under the same semi-roughing machine setting as
Experiment 3 of C140 and the depth of cut was again 1mm deeper. Again the results
in all areas were very similar to the results of Experiment 3.
The following is the depth of cut for the forth set of experiments:
Cone Electrode – 31mm
Triangle Electrode – 29mm
Base Electrode – 22mm
48
5.4.1 Solid Electrodes compared to Electroformed Electrodes
Again the solid and electroformed electrodes provided comparable performance over
the range of shapes. The solid base electrode (Figure A.35) shows very similar results
to the electroformed base electrode (Figure A.36) and to previous experiments except
the wear on the electrodes has increased on average over the whole electrode. Both
electrodes have shown very consistent results in terms of wear which is less than
0.1mm over the machining surfaces which are similar to Experiment 3. The solid
electrodes still perform marginally better than the electroformed electrodes but both
still show more wear on the sharp edges and corners.
The cone electrodes (Figure A.37 and Figure A.38) are also showing very similar
CMM results to Experiment 3 except the wear is becoming more even across the
machining surfaces and not localised in the centre on the tip of the electrode. The
wear is still approximately in the vicinity of 0.05mm compared to less than 0.05mm on
average for Experiments 1 and 2.
The solid triangle electrode (Figure A.39) has shown very small wear on the
machining surfaces which is less than 0.03mm but it is very similar in magnitude to
Experiment 3. The electroformed triangle electrode continues to shown signs of
warping on the large flat surfaces (Figure A.40).
5.4.2 Work pieces machined by different electrodes
Apart from the few major spikes the work pieces have been machined very evenly.
The solid electrode (Figure A.42) has machined almost exactly 1mm over the surface
of the work piece. Experiment 3 results influenced the performance of the
electroformed electrode in Experiment 4. The lack of machining was made up in this
experiment as shown in Figure A.42 by the CMM measuring over 1mm for most of
the work piece surface.
49
Again the Cone work pieces have shown relatively even machining over the work
pieces but Experiment 4 was influenced by the results of previous experiments. The
solid electrode removed an average of 1.2mm (Figure A.43) because Experiment 3
only removed 0.8mm on average. Extra machining was also needed by the
electroformed cone electrode (Figure A.44) due to the warping occurring in previous
experiments and not machining the complete 1mm.
The work pieces for the triangle electrodes show the relatively even machining for the
solid electrodes (Figure A.45) the erratic performance of the electroformed electrode
(Figure A.46) from the electrode warping.
The change in mass shown in Table 5.16 shows that Experiment 4 has followed the
trends of the previous experiments in that there is more wear occurring on the
electroformed electrodes. The wear occurring on the solid base electrode was
measured at 0.0 and that result is due to the accuracy of the scales that were available.
The zero measurement also affects the TWR results in subsequent calculations.
Machining time for Experiment 4 (Table 5.17) has increased with comparison to
Experiment 3. The reason for the increase in machining time is because more material has
been removed. The machining area has increased to include the flange area as the
electrode is cutting deeper than the height of the shape of the electrode. The increased
machining time is better compared in the MRR.
The MRR is very similar to Experiment 3 and the electrodes have all performed to a
similar rate between 0.1 to 0.15 grams per minute (Table 5.18).
The wear is slightly more on the electroformed electrodes and also overall measurably
more than the first two experiments. Because the TWR is measured on electrode wear
divided by work piece wear, the resulting TWR (Table 5.19) is similar to the previous
experiments.
50
Table 5.16 – Change in Mass for Experiment 4
Change in Mass Grams
Solid Base Electrode 0.0
Electroformed Base Electrode 0.506
Solid Cone Electrode 0.18
Electroformed Cone Electrode 0.129
Solid Triangle Electrode 0.01
Electroformed Triangle Electrode 0.18
Base Work piece (solid) 17.1
Base Work piece (electroformed) 21.0
Cone Work piece (solid) 14.1
Cone Work piece (electroformed) 10.9
Triangle Work piece (solid) 6.6
Triangle Work piece (electroformed) 9.2
Table 5.17 – Machining Time for Experiment 4
Machining Time Minutes
Solid Base Electrode 119.63
Electroformed Base Electrode 211.33
Solid Cone Electrode 107.85
Electroformed Cone Electrode 93.97
Solid Triangle Electrode 47.78
Electroformed Triangle Electrode 69.28
Table 5.18 – Material Removal Rate for Experiment 4
Material Removal Rate Grams/MinuteBase Work piece (solid) 0.143
Base Work piece (electroformed) 0.099
Cone Work piece (solid) 0.131
Cone Work piece (electroformed) 0.116
Triangle Work piece (solid) 0.138
Triangle Work piece (electroformed) 0.133
51
Table 5.19 – Tool Wear Rate for Experiment 4
Tool Wear Rate Percentage (%)
Solid Base Electrode 0.000
Electroformed Base Electrode 2.410
Solid Cone Electrode 1.277
Electroformed Cone Electrode 1.183
Solid Triangle Electrode 0.152
Electroformed Triangle Electrode 1.957
The surface roughness (Table 5.20) measured, as expected, almost equal to
Experiment 3 and also shows that the finish is smoother than the first two experiments.
Table 5.20 – Average Surface Roughness Ra μm, Experiment 4
Ra Average μm Cone Work piece (electroformed) FC2e 5.12
Cone Work piece (solid) FC3e 5.54
Triangle Work piece (electroformed) FT1e 6.04
Triangle Work piece (solid) FT2e 5.61
Base Work piece (electroformed) FB2e 5.59
Base Work piece (solid) FB1e 5.53
5.5 EXPERIMENT 5
Experiment 5 is the first of two finishing cuts at a machine setting of C110. The
finishing cut produced a very low MRR and lower Ra. The machining time increased
dramatically and the TWR followed the trend and increased.
52
The machine and actual settings were as follows:
Nominal Actual
Machine Setting: C110 C110
Discharge Pulse Duration (ON): 012 80μsec
Quiescent Pulse Duration (OFF): 012 20μsec
Quiescent Time (MA): 01 X2
Peak Current (IP): 002.0 2A
Servo Voltage (SV): 03 35V
Polarity (PL): + +
The following is the depth of cut for the fifth set of experiments:
Cone Electrode – 31.5mm
Triangle Electrode – 29.5mm
Base Electrode – 22.5mm
Experiment 5 saw the introduction of the second new set of solid electrodes. Due to
budget constraints the number of electrodes produced was reduced and therefore the
same electrodes were used several times.
5.5.1 Solid Electrodes compared to Electroformed Electrodes
The introduction of the new solid electrodes reduced the tool wear. CMM
measurements in Figure A.47 show that the wear on the solid electrode measured less
than 0.005mm apart from several points on the sharp edges that measure
approximately 0.01mm. The new electrode performed much better than expected
because it doesn’t follow the trend of more wear as the cutting becomes finer. The
electroformed base electrode followed all of the trends with increased overall wear and
this was shown in Figure A.48. The CMM has measured the wear over the majority of
the electrode at approximately 0.05mm.
The cone electrodes also showed the result of the introduction of the new solid
electrodes. The solid cone electrode resulted in CMM measurements (Figure A.49) of
less than 0.04mm. Wear on the electrode was very small and didn’t register any
53
change in mass to two decimal places. The electroformed electrode showed
significantly more wear (Figure A.50) and it continued the trend of greater wear for
finer cuts.
The triangle electrodes have followed the same trends as previous electrodes in
experiment 5. The new solid electrode (Figure A.51) has shown very little wear over
the electrodes machining surface and this is also shown by the change in mass (Table
5.21). The electroformed electrode showed much more wear than the solid electrode
as well as previous experiments using electroformed triangle electrodes. The CMM
measurements (Figure A.52) also show that some warping has also occurred during
the experiment.
5.5.2 Work pieces machined by different electrodes
Machining with the new solid base electrode produces a cavity that didn’t actually
reach the 0.5mm depth of cut that was set. The new electrode used for experiment 5
connects to the EDM tool holder slightly different to the first solid electrode and
therefore not machining on exactly the same plane. The CMM measurements in
Figure A.53 show that the electrode machined at a very slight angle and a depth of
approximately 0.45mm.
Previous experiments have affected the depth of cut by the electroformed base
electrode. Figure A.54 shows that the depth of cut reached the set 0.5mm but the
depth was uneven across the machined surface. The electrode was also slightly bowed
across the flange of the electrode which prevented the electrode from machining
evenly. Figure 5.11 shows the electroformed electrode and that the front of the
electrode is untouched and that is shown in the CMM measurements.
The machining of the solid cone electrode reached the depth of 0.5mm but because it
is a new electrode, the setup is slightly different and therefore the electrode performs
slightly different. The erratic performance of the electroformed electrode is shown in
Figure 5.12 by the silver sections of the electrode that haven’t been involved in any
machining. The CMM (Figure A.55) has measured the machining to be slightly off-
54
centre and therefore machining a small amount more from the cavity. The
electroformed electrode has performed very erratically (Figure A.56) and this is a
result of previous experiments.
Figure 5.11 – Electroformed Base Electrode – Experiment 5
The triangle work pieces have followed the expected trends. The solid electrode has
machined fairly evenly over the surface (Figure A.57) which was expected. The
machining wasn’t completely down the set 0.5mm cut but that can be explained by the
spark gap reducing from the previous experiment and the wear on the previous
electrode. The sharp edges and the centre ridge of the electrode performed
approximately 0.5mm because the first electrode was slightly worn from previous
experiments. Figure A.58 continues to show how the triangle electroformed electrode
machines erratically due to the previous experiments and the warping of the electrode
shells.
Figure 5.13 shows how the electrode used in experiment 4 has made a cut to a depth of
29mm but due to the wear on the tip of the electrode the depth of cut is uneven
compared to the cut made in Experiment 5. Experiment 5 machined to a depth of
29.5mm but the tip of the electrode performed more work as a result of the previous
electrode.
55
Figure 5.12 – Electroformed Cone Electrode – Experiment 5
The depth of cut is measured from the tip of the electrode to the top surface of the
electrode. As the first electrode wore more on the tip than the flat surfaces therefore
making the larger flat surfaces do more machining.
Figure 5.13 – Measurements of the different performances of Experiment 4 and
Experiment 5
Experiment 5 followed the trend of previous experiments in that more wear occurred
on the electroformed electrodes. The introduction of new solid electrodes has
produced minimal wear on the solid electrodes and was unmeasurable in terms of
mass on the cone and triangle electrodes (Table 5.21). The work pieces had similar
amounts of material removed for each electrode shape.
0.5mm
0.45mm
Experiment 4 – 29mm – Worn Experiment 5 – 29.5mm – New Work
Piece Not to scale
Cut Direction
56
Table 5.21 – Change in Mass for Experiment 5
Change in Mass Grams
Solid Base Electrode 0.1
Electroformed Base Electrode 0.835
Solid Cone Electrode 0.00
Electroformed Cone Electrode 0.165
Solid Triangle Electrode 0.00
Electroformed Triangle Electrode 0.260
Base Work piece (solid) 5.7
Base Work piece (electroformed) 3.5
Cone Work piece (solid) 4.0
Cone Work piece (electroformed) 4.8
Triangle Work piece (solid) 3.2
Triangle Work piece (electroformed) 3.3
The machining time for Experiment 5 has increased dramatically. An increase in time
was expected as the finishing cut has less current and voltage running through the
electrode and therefore the spark produced is smaller and removes less material per
spark. Table 5.22 shows the measured machining times and the solid electrodes made
the set cuts in considerably less time than the electroformed electrodes but Experiment
5 has increased from an average of 108.31min (Experiment 4) to 563.63min.
Table 5.22 – Machining Time for Experiment 5
Machining Time Minutes
Solid Base Electrode 483.45
Electroformed Base Electrode 990.03
Solid Cone Electrode 345.78
Electroformed Cone Electrode 758.90
Solid Triangle Electrode 316.83
Electroformed Triangle Electrode 486.80
57
The MRR (Table 5.23) shows that the solid electrodes perform much better than the
electroformed electrodes. The MRR has dropped significantly from Experiments 3
and 4.
Table 5.23 – Material Removal Rate for Experiment 5
Material Removal Rate Grams/Minute
Base Work piece (solid) 0.012
Base Work piece (electroformed) 0.004
Cone Work piece (solid) 0.012
Cone Work piece (electroformed) 0.006
Triangle Work piece (solid) 0.010
Triangle Work piece (electroformed) 0.007
The use of new electrodes has reduced the TWR in Experiment 5 (Table 5.24) for the
solid electrodes but the TWR for the electroformed electrodes has increased
significantly.
Table 5.24 – Tool Wear Rate for Experiment 5
Tool Wear Rate Percentage (%)
Solid Base Electrode 1.754
Electroformed Base Electrode 23.857
Solid Cone Electrode 0.000
Electroformed Cone Electrode 3.437
Solid Triangle Electrode 0.000
Electroformed Triangle Electrode 7.879
The surface roughness of the work pieces in experiment 5 (Table 5.25) dropped from
an average of approximately 5.4μm in experiments 3 and 4 to 3.8μm. The drop in
surface roughness was expected with the machine setting of C110.
58
Table 5.25 – Average Surface Roughness Ra μm, Experiment 5
Ra Average μm
Cone Work piece (electroformed) FC2f 3.50
Cone Work piece (solid) FC3f 2.61
Triangle Work piece (electroformed) FT1f 5.15
Triangle Work piece (solid) FT2f 3.96
Base Work piece (electroformed) FB2f 3.43
Base Work piece (solid) FB1f 4.34
5.6 EXPERIMENT 6
Experiment 6 was conducted under the same finishing machine setting as Experiment
5 of C110 and the depth of cut was again 0.5mm deeper. Again the results in all areas
were very similar to the results of Experiment 5.
The following is the depth of cut for the sixth set of experiments:
Cone Electrode – 32mm
Triangle Electrode – 30mm
Base Electrode – 23mm
5.6.1 Solid Electrodes compared to Electroformed Electrodes
Experiment 6 gave very similar results in the performance of the solid base electrode
(Figure A.59) to Experiment 5. The majority of the wear measured less than 0.005mm
and a few sharp points of the electrode measured higher. The electroformed electrode
showed similar performance to Experiment 5 except for the delamination of the
electrode which is shown by measurements of over -2mm and in Figure A.60.
The delamination (Figure 5.14) occurred during the experiment and was only visible
on completion of the experiment. The delamination was caused by inconsistent build
up during the electroforming process and therefore the process depositing a separate
layer into the mould.
59
Figure 5.14 – Electroformed Base Electrode – Experiment 6
The cone electrodes showed slightly more wear than Experiment 5 but the majority of
wear was less than 0.1mm and it was fairly even over the whole electrode for both the
solid electrode and the electroformed electrode (Figure A.61 and Figure A.62).
The triangle electrodes again followed the same trends as the previous experiments.
The solid electrode (Figure A.63) measured minimal wear on the CMM and the
electroformed electrode (Figure A.64) again showed some warping occurring during
the machining process.
5.6.2 Work pieces machined by different electrodes
The machining done by the solid base electrode shows almost exactly what was
expected. The graph in Figure A.65 shows that the CMM has measured very close to
0.5mm over the entire machined surface. The electroformed electrodes performance
was affected by previous experiments but the CMM measured very close to 0.5mm
over the surface. Figure A.66 shows a large spike in the CMM measurements across
60
the back of the work piece. This spike was caused by the delamination of the
electrode as shown in Figure 5.14 and the machining done by the copper that peeled
away.
Again the solid cone electrode has performed as expected measuring very close to 0.5mm
on the machined surface (Figure A.67). Figure A.68 is the result of the warping in the
previous experiment and the electrode has had to machine the material not machined in
Experiment 5 and also there is little work done in the areas where extra machining was
done in Experiment 5.
The solid triangle electrode performed as expected and shows approximately 0.5mm over
the machined surface (Figure A.69). The electroformed electrode also followed the trends
and machined very erratically over the surface (Figure A.70) as it did in previous
experiments.
Experiment 6 follows the previous experiments by showing more wear on the
electroformed electrodes (Table 5.26) even though the same shapes remove similar
amounts of material.
Table 5.26 – Change in Mass for Experiment 6
Change in Mass Grams
Solid Base Electrode 0.1
Electroformed Base Electrode 1.08
Solid Cone Electrode 0.05
Electroformed Cone Electrode 0.472
Solid Triangle Electrode 0.05
Electroformed Triangle Electrode 0.129
Base Work piece (solid) 7.8
Base Work piece (electroformed) 9.0
Cone Work piece (solid) 5.6
Cone Work piece (electroformed) 4.4
Triangle Work piece (solid) 5.6
Triangle Work piece (electroformed) 4.9
61
Machining time (Table 5.27) for each electrode shape was more similar when comparing
the times to Experiment 5 which had exactly the same machine settings. Due to the
delamination problems encountered with the electroformed electrode the machining time
was dramatically increased.
Table 5.27 – Machining Time for Experiment 6
Machining Time Minutes
Solid Base Electrode 598.42
Electroformed Base Electrode 1947.75
Solid Cone Electrode 447.63
Electroformed Cone Electrode 651.87
Solid Triangle Electrode 524.72
Electroformed Triangle Electrode 598.15
The MRR for Experiment 6 is almost identical to that of Experiment 5. The solid
electrodes performed better than the electroformed electrodes with a greater MRR
(Table 5.28).
Table 5.28 – Material Removal Rate for Experiment 6
Material Removal Rate Grams/Minute
Base Work piece (solid) 0.013
Base Work piece (electroformed) 0.005
Cone Work piece (solid) 0.013
Cone Work piece (electroformed) 0.007
Triangle Work piece (solid) 0.011
Triangle Work piece (electroformed) 0.008
Again the TWR (Table 5.29) for the solid electrodes is very low but has increased
from Experiment 5 and that was because the electrodes are the same ones used in the
previous experiment. The electroformed electrodes TWR have also increased similar
to Experiment 5.
62
Table 5.29 – Tool Wear Rate for Experiment 6
Tool Wear Rate Percentage (%)
Solid Base Electrode 1.282
Electroformed Base Electrode 12.000
Solid Cone Electrode 0.893
Electroformed Cone Electrode 10.727
Solid Triangle Electrode 0.893
Electroformed Triangle Electrode 2.633
The surface roughness has stayed similar to Experiment 5 and the results in Table 5.30
show the Ra average at approximately 4μm.
Table 5.30 – Average Surface Roughness Ra μm, Experiment 6
Ra Average μm Cone Work piece (electroformed) FC2g 3.58
Cone Work piece (solid) FC3g 3.06
Triangle Work piece (electroformed) FT1g 4.50
Triangle Work piece (solid) FT2g 3.53
Base Work piece (electroformed) FB2g 6.29
Base Work piece (solid) FB1g 3.64
5.7 SUMMARY OF ALTERNATIVE ELECTRODE MANUFACTURE AND PERFORMANCE COMPARISON
This section provides a summary of the different electrode manufacturing methods and
gives comparisons in the areas of cost, quality and performance. Even though the
spray metal shells were not successful, the cost comparison was included and due to
the cost of manufacture it would be worth while continuing to develop the technology.
The spray metal shells weren’t successful because the shells had imperfections and the
backfilling broke through the shells. The spray metal shells were produced using
copper wire passed through a Sulzer Metco electric-arc metal spray system. The shell
63
thickness was specified at a minimum of 2mm but the problem areas of the mouldings
were the deep pockets and sharp corners.
Figure 5.15 shows the spray metal shell with the backfilled material protruding. The
possible causes of the failures include the depth of the negative moulds and also the
porosity of the spray metal. Research has shown that the spray metal method cannot
produce a dense enough shell or moulding to be a viable option for industry needs.
Other researchers have managed to achieve densities of 85% to 95% of the density of
solid copper which shows promise for the use of spray metal in rapid tooling in future
research [58].
Figure 5.15 – Defective spray metal shells
5.7.1 Detailed Failure Investigation of Spray Metal Electrodes
The following problems were encountered with the production of spray metal
electrodes:
• A shell thickness of 2mm was requested to give sufficient material to form the
shell. Analysis shows that some sections are up to 3mm thick but other areas
show a serious lack of build up and this has lead to the backing material
breaking through the shell surface and rendering the electrode unusable. It is
very difficult to control where and how thick the material will build up
especially when spraying into deeper cavities. Figure 5.16 shows the thin wall
sections highlighted in the red circles.
64
Figure 5.16 – Sectional Views of Spray Metal Electrodes showing wall thicknesses
• The thickness of the wall sections was directly linked to the angle they faced
the direction of the spray nozzle. Greater material build up was measured on
the surfaces that were closer to perpendicular to the nozzle flow. The surfaces
that were close to parallel received less material and therefore were prone to
failure. If possible the material build up is optimised by getting the spray
direction as close to perpendicular to the nozzle when spraying metal.
• To get the best EDM results the surface of the electrodes need to be as smooth
as possible and the electrodes produced by spray metal deposition were
extremely rough. Figure 5.17 gives a visual comparison between the different
electrode production techniques where the Electroformed electrode is rough
and the machined electrode has a polished surface. Due to the roughness of
the spray metal electrodes the surface roughness (Ra) was not possible to
measure with the same settings and equipment used to measure the
electroformed and solid electrodes. The Ra of the electrode surface was
65
outside the measurable scale of the probe used to measure the surface
roughness and therefore no accurate measurements were attainable.
Figure 5.17 – Visual Surface Roughness comparison between Spray Metal (left) and
Solid Machined Electrodes (right)
• The spray metal process is extremely rough and the actual mould needs to be
tough enough to resist the corrosiveness and temperatures of the spray metal
process. It was found that the molten copper penetrated the surface of the
ceramic moulds that were used and that meant the smooth ceramic surface
could not be reproduced on the electrode shell surface.
• Shell imperfections were present throughout the spray metal shells and these
were also factors that prevented them from being usable. Imperfections such
as inclusions, porosity, and cracking were visible and these problems could be
reduced if there was more refining of the spray metal process. Figure 5.18
shows cracking, white ceramic inclusions and darker areas where the porosity
has allowed some of the backing material to leak through. Adjusting
parameters such as temperature, material flow and mould material may allow
the process to produce usable shells.
66
Figure 5.18 – Surface imperfection in the spray metal shells.
Proposed ways to improve the Spray Metal Electrodes
To allow spray metal to be used for EDM electrode design, some solutions that could
help refine process include:
• Allowing more material to be deposited to meet a minimum wall thickness
across the entire surface and therefore reducing any chances of the backing
material breaking through the shell,
• Placing restrictions on the depth of cavities to be sprayed would reduce the
angles required to get the spray nozzle close to perpendicular when spraying
each surface,
• The moulds need to be made from tougher materials to allow a better
reproduction of the electrode surface. The materials that could be used need to
have a higher resistance to a combination of heat and wear,
• More time, effort and money is needed to refine the spray metal process for
the production of EDM Electrodes.
5.7.2 Cost Comparison
The viability of the electrodes also depends on the cost to produce the electrodes. The
cost comparison is done on the electrodes that were used in this study.
67
The cost of manufacturing the electroformed electrodes includes:
• Master Patterns SLA,
• Silicon negative patterns,
• Electroformed Copper Shells,
• Backfilled with Aluminium filled Urethane,
• Machining mounting surface.
The cost of the manufacture of the solid copper electrodes includes:
• Solid copper Material,
• Machining different electrode shapes,
• Machining mounting surface.
The cost of manufacture of the spray metal electrodes includes:
• Master Patterns SLA,
• Ceramic negative patterns,
• Spray metal shells,
• Backfilled with Aluminium filled Urethane,
• Machining mounting surface.
Even though there are less steps in manufacturing the solid electrodes the cost of
manufacture exceeds that of the electroformed and spray-metal electrodes. The cost of
manufacture is only a rough guide as the prices given were for research purposes and
not commercial prices. Table 5.31 shows the cost of manufacture of the electrodes.
Manufacturing times of the electrodes will vary depending on the number of pieces
required. It takes approximately 16 hours to manufacture one set of three electrodes
from solid copper. Manufacturing time for the solid electrodes increase equally with
the number of electrodes as each electrode is manufactured separately. Therefore the
cost of each solid electrode will only vary a little from the original prices given.
The major time consuming part of manufacturing electroformed electrodes is the
electroforming process and it takes approximately 50 hours to manufacture one set of
three electrodes from one mould. Manufacturing time can be dramatically reduced as
68
the number of moulds that can be electroformed is unlimited. The only limitations are
the size of the solution bath and the number of moulds manufactured.
Table 5.31 – Manufacturing Cost Comparison of different Processes
Process Quantity Cost Electroformed Electrodes Master Patterns SLA – 1 shape @ $100 3 shapes $300.00Silicon negative patterns – 3 shapes @ $230 1 set $690.00Electroformed Copper Shells – 3 shapes @ $200 6 sets $600.00Backfilled Aluminium filled Urethane – 1 set @ $92 6 sets $550.00Manual Machining mounting surface – 6 sets @ $100/hour 3 hours $300.00Total Cost – 18 electrodes 6 sets $2440.00Unit Price $135.56Solid Electrodes Solid Copper Material – 1 blank @ $50 6 blanks $300.00Machining electrode shapes – 6 electrodes @ $140/hour 31.5 hours $4,420.00CNC Machining mounting surface – 2 sets @140/hour 1 hour $140.00Total Cost – 6 electrodes 2 sets $4860.00Unit Price $810.00Spray Metal Electrodes Master Patterns SLA – 1 shape @ $100 3 shapes $300.00Ceramic negative patterns – 3 shapes @ $75 6 sets $450.00Spray metal shells – 3 shapes @ $120 6 sets $720.00Backfilled Aluminium filled Urethane – 1 set @ $92 6 sets $550.00Manual Machining mounting surface – 6 sets @ $100/hour 3 hours $300.00Total Cost – 18 electrodes 6 sets $2320.00Unit Price $128.89
Spray metal electrode manufacturing process can be slightly reduced by increasing the
number of cavities in each mould but it is best to make them separately to make sure
an even shell thickness if maintained. The manufacture of the spray metal electrodes
takes approximately 12 hours per set of three electrodes.
Although it is hard to find definite figures on cost comparisons in previous research
there are several research groups that indicate that their research has shown cost saving
potential in these areas of manufacture [19, 22-24, 26, 28, 34, 44, 45, 48, 59]. As
indicated, electroforming and spray-metal can save significantly in cost of
manufacture of electrodes compared to traditional machining. Solid electrodes cost
69
approximately $810 each which is six times more expensive than the electroformed
and spray-metal electrodes at approximately $130.
5.7.3 Performance Comparison of Manufacturing Methods
Figure 5.19 shows that the solid electrodes performed better as the machining became
finer with the finishing cuts. The time taken for each cut at the finer settings (C110)
was much higher and erratic for the electroformed electrodes. All experimental times
are tabulated in Table 5.32.
The machine settings for the three levels of machining as shown in Table 3.2 show
that as the machining goes from C170 (roughing) down to C110 (finishing) the Pulse
ON and OFF drops as does the Peak Current and Servo Voltage. As the parameters
drop the machining time should increase, the MRR should decrease, the TWR should
increase and the Ra should reduce. As the experiments have shown previously in this
chapter, the results followed the expected trends in that the machining time increased,
the MRR decreased and the Ra decreased. The TWR measured as expected for the
electroformed electrodes but the solid electrodes performed against the expected trend.
Table 5.32 – Machining Time Comparison for different electrodes at various settings
Machining Time Table Machine Setting Tool type C170 C170 C140 C140 C110 C110 Electroformed Base 46.80 49.53 89.83 211.33 990.03 1947.75Electroformed Cone 43.37 8.12 77.40 93.97 758.90 651.87Electroformed Triangle 50.83 13.23 46.80 69.28 486.80 598.15Solid Base 19.47 39.40 95.72 119.63 483.45 598.42Solid Cone 85.52 12.53 46.58 107.85 345.78 447.63Solid Triangle 58.02 17.15 49.17 47.78 316.83 524.72
For both electrode types the machine time for the machine setting of C170 (roughing
cut) was very similar and also very consistent over the six experiments conducted. As
the experiments become more refined with the semi-roughing cut (C140) the solid
electrodes start to perform better as the machining time is less than the electroformed
electrodes and the trendlines begin to separate. The solid electrodes also remain more
70
consistent than the electroformed electrodes. The electroformed electrodes begin to
perform a little more erratic.
Machining Time Comparison
0.00
500.00
1000.00
1500.00
2000.00
2500.00
100 110 120 130 140 150 160 170 180
Machine Setting (C value)
Tim
e (m
in)
Electroformed Electrodes Solid Electrodes Electroformed Electrode Trend Solid Electrode Trend
Figure 5.19 – Machining time Comparison
As seen in Figure 5.19 the trend line shows that a greater gap has formed between the
performances of the different electrode types. Again the solid electrodes have shown
better performance than the electroformed electrodes in terms of the average
machining time and the consistency of the performance.
Table 5.33 shows the MRR results tabulated from all of the experiments. The solid
electrodes showed better performance in MRR, as shown graphically in Figure 5.20,
when performing the roughing cuts but all electrodes performed similarly when a
finishing cut was applied. According to Leu et al. [15] the results of the experiments
are similar (Figure 5.21 and Table 5.34) to the results gained in this research in that the
MRR is much higher for the roughing setting and reduces as the machine settings
change towards the finishing cuts. Figure 5.21 shows that the trendlines for the results
of Leu et al. [15] are almost identical and the graph shows the trendlines overlapping.
71
When comparing the MRR results the required accuracy to determine any significant
difference was measured down to an accuracy of 0.001 grams per minute. This
accuracy was only needed when the machining was at the finishing setting of C110
where the machining time increased dramatically. For all other machine settings an
accuracy of 0.01 g/min would have been sufficient to determine any differences.
Table 5.33 – MRR Comparison for different electrodes at various settings
MRR C170 C170 C140 C140 C110 C110 Female Base (Electroformed) 0.229 0.331 0.142 0.099 0.004 0.005
Female Base (Solid) 0.396 0.416 0.160 0.143 0.012 0.013Female Cone (Electroformed) 0.422 0.099 0.116 0.116 0.006 0.007
Female Cone (Solid) 0.232 0.343 0.090 0.131 0.012 0.013Female Triangle (Electroformed) 0.354 0.302 0.143 0.133 0.007 0.008
Female Triangle (Solid) 0.377 0.367 0.142 0.138 0.010 0.011
MRR Comparison
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
100 110 120 130 140 150 160 170 180
Machine Setting (C value)
Gra
ms
per m
in
Work piece (Electroformed) Work piece (Solid) Work Piece (Solid) Trend Work Piece (Electroformed) Trend
Figure 5.20 – MRR Comparison
The average MRR for the solid electrodes shown by the trend line in Figure 5.20 is
better than that of the electroformed electrodes for a roughing cut with a difference of
over 0.05 grams per minute. The performance of the electroformed electrodes has
again shown that it is more erratic than the performance of the solid electrodes. As the
machine settings become the finer the performance of the electrodes converge. The
72
MRR becomes less erratic for both electrode types at the finishing cut machine
settings.
Table 5.34 – MRR Comparison for different electrodes at various settings for research
by Leu, Yang and Yao [15]
R Figure 5.21 – MRR Comparison for research by Leu, Yang and Yao [15]
73
The TWR (Table 5.35) for the solid electrodes was affected by the use of only two
electrodes for 6 experiments and therefore the results are not completely accurate. The
electroformed electrodes however performed as expected and shows greater TWR as
the machine setting decreases. Compared to the research by Leu et al. [15] (Figure
5.23 and Table 5.36) the TWR is similar for the Electroformed electrodes in that the
TWR increases as the experiments go from roughing to finishing cuts. The solid
electrodes don’t perform as expected as the results were affected by the use of the
same electrodes more than once. Figure 5.22 shows graphically how the different
types of electrodes performed across the different machine settings.
The accuracy of TWR only needed to be down to 0.1 % to get a reasonable
comparison except when there was no measurable TWR for some of the solid
electrodes. Where the TWR did not register a figure the reason was because the scales
didn’t measure any change in mass. If more accurate scales were used to measure the
change in mass the result would still be so small that the resulting TWR would be
insignificant in the comparisons anyway.
Table 5.35 – TWR Comparison for different electrodes at various settings
TWR C170 C170 C140 C140 C110 C110 Electroformed Base 1.804 2.122 1.375 2.410 23.857 12.000 Electroformed Cone 0.672 10.750 1.689 1.183 3.437 10.727 Electroformed Triangle 1.994 1.825 1.746 1.957 7.879 2.633 Solid Base 1.299 1.220 0.654 0.000 1.754 1.282 Solid Cone 1.919 1.163 1.190 1.277 0.000 0.893 Solid Triangle 2.831 0.317 2.286 0.152 0.000 0.893
74
TWR Comparison
0.000
5.000
10.000
15.000
20.000
25.000
30.000
100 110 120 130 140 150 160 170 180
Machine Setting (C value)
Perc
enta
ge %
Electroformed Electrodes Solid Electrodes Electroformed Electrodes TrendSolid Electrodes Trend
Figure 5.22 – TWR Comparison
Table 5.36 – TWR Comparison for different electrodes at various settings for research
by Leu, Yang and Yao [15]
75
Figure 5.23 – TWR Comparison for research by Leu, Yang and Yao [15]
Therefore as shown in all comparison graphs, the solid electrodes have out performed
the electroformed electrodes in almost every aspect of measurable performance. The
overall results of the electrodes is similar in comparison to the research completed by
Leu et al., Jensen et al. and Yarlagadda et al. [15, 16, 18].
76
6.0 CONCLUSIONS
Manufacture of three different shapes of electrodes in three different manufacturing
methods was achieved. The solid copper and electroformed copper electrodes were
manufactured successfully to the experimental stage however the spray metal
electrodes were unusable.
The experiments with the solid electrodes and electroformed electrodes were
conducted with success at three different machines setting and comparisons were able
to be made. The solid electrodes consistently performed better than the electroformed
electrodes at all machine settings as shown in the summary graphs of the performances
in Machining Time, MRR and TWR.
The major problems encountered with the electroformed electrodes included:
• problems with setup and conductivity,
• shell thickness is hard to control and cavities are difficult to build evenly,
• the electroformed shells are easily damaged,
• the backing material doesn’t have the same conductivity as the copper,
• the copper shells are prone to warping under thermal stress,
• delamination is possible,
Although the solid electrode has out performed the electroformed electrodes in the
majority of the experiments, the solid electrodes are much more expensive to produce.
The standard workshop is more likely to have a machining centre to machine solid
electrodes as opposed to an electroplating system to produce electroformed electrodes.
So the convenience of the solid electrodes will often out way the use of electroformed
electrodes.
The cost of electrodes becomes a major factor as soon as the electrode manufacturing
process becomes more comparable. Even though the solid electrodes out performed
the electroformed and spray metal electrodes, the cost of manufacture plays a vital role
in the tooling process. This research has shown that the cost of solid electrodes is
77
$810 each which is six times that of electroformed and spray metal electrodes at $130
each.
Solid electrodes take approximately six hours to produce where as a single
electroformed electrode will take up to 50 hours to produce. The cost of production is
sometimes not the critical factor when rapid tooling is required. For low numbers of
electrodes it is probably more economical in terms of time to use traditional
machining. However when a large number of electrodes are required, electroforming
will take a similar amount of time to produce one electrode as it will take to produce
an infinite number of electrodes and therefore becoming faster as long as more than 10
electrodes are required..
The research has given similar results to research done by Leu et al. [15], Jensen et al.
[16] and Arthur et al. [14] in that the traditionally produced electrodes performed in a
similar manner to the non-traditional (electroformed) electrodes. If the electroformed
electrodes could be produced with a much more even shell thickness it might reduce
the erratic performance of the electroformed electrodes. Although the electroformed
electrodes performed on average comparable to the solid electrodes there seemed to be
a greater difference between the best and worst performances of the electrodes at each
machine setting.
It is recommended that more refinements need to be done on the electroforming
process to get a greater understanding of the performance characteristics of the
electrodes. Also a greater number of experiments need to be conducted to prove the
repeatability of the electroformed electrodes. Leu et al. [15] conducted eight
experiments at each machining level and others like Arthur et al. [14] conducted over
72 experiments in Fractional Factorial Experiments and Taguchi methods to optimise
the parameters for MRR and the same amount of experiments would be needed to
optimise TWR and Ra. Optimising the machine parameters using Fractional Factorial
Experiments and Taguchi methods is a way that research could promote the use of
electroformed electrodes.
The electroforming process could be a viable option for the EDM process if the
electrodes could be produced more robust and consistent shell thickness. Problems
78
with the shell thickness produced warping and delamination on some of the larger flat
surfaces. With greater control over the wall thickness and greater heat conductivity of
the backing material would give better performance of the electroformed electrodes.
With more investigation into spray metal applications and capabilities it would prove
to be a promising method of electrode manufacture. This project was unable to apply
the time and resources needed to research spray metal to the degree that would be
needed to get the process to a usable standard.
Other areas in EDM that could benefit from more research include:
• Flushing systems for deep cavities,
• Conductive backing materials for the electrode shells,
• Setup and tooling for the electrode attachment to the EDM tool
post to increase the conductivity,
• And investigation into the thermal stresses occurring in the
electroformed electrode shells and backing material.
79
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84
Appendix
85
16.0
00
12.0
00
8.00
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4.00
0
0.00
0
-4.0
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-8.0
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-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
0.200
0.250
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SC1a-b
Figure A.1 - Cone Electrode Wear Experiment 1 - Solid Electrode
86
16.0
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8.00
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4.00
0
0.00
0
-4.0
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-8.0
00
-12.
000
-16.
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16.000
10.000
4.000
-2.000
-8.000-14.000
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
0.200
0.250
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC1a-b
Figure A.2 - Cone Electrode Wear Experiment 1 - Electroformed Electrode
87
-16.
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-12.
000
-8.0
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-4.0
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0.00
0
4.00
0
8.00
0
12.0
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16.0
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-16.000
-10.000
-4.000
2.000
8.00014.000
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ST1a-b
Figure A.3 – Triangle Electrode Wear Experiment 1 - Solid Electrode
88
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ET1
Figure A.4 – Triangle Electrode Wear Experiment 1 - Electroformed Electrode
89
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000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
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-2.0
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2.00
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6.00
0
10.0
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14.0
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18.0
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22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FB1 a-b
Figure A.5 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Solid Electrode Work Piece
90
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FB2 a-b
Figure A.6 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Electroformed Electrode Work Piece
91
-20.
000
-16.
000
-12.
000
-8.0
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-4.0
00
0.00
0
4.00
0
8.00
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12.0
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16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-1.000
0.000
1.000
2.000
3.000
4.000
5.000
6.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FC3 a-b
Figure A.7 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Solid Electrode Work Piece
92
-20.
000
-16.
000
-12.
000
-8.0
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-4.0
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0.00
0
4.00
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8.00
0
12.0
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16.0
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20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-1.000
0.000
1.000
2.000
3.000
4.000
5.000
6.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FC2 a-b
Figure A.8 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Electroformed Electrode Work Piece
93
-20.
000
-16.
000
-12.
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-8.0
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-4.0
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0.00
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8.00
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12.0
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16.0
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20.0
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-20.000
-12.000
-4.000
4.000
12.00020.000
-5.000
0.000
5.000
10.000
15.000
20.000
25.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT2a-b
Figure A.9 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Solid Electrode Work Piece
94
-20.
000
-16.
000
-12.
000
-8.0
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-4.0
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0.00
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8.00
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12.0
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16.0
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20.0
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-20.000
-12.000
-4.000
4.000
12.00020.000
-5.000
0.000
5.000
10.000
15.000
20.000
25.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT1a-b
Figure A.10 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Electroformed Electrode Work Piece
95
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
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-4.0
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0.00
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4.00
0
8.00
0
12.0
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16.0
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20.0
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24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-0.500
-0.400
-0.300
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
0.500
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SB2 b-c
Figure A.11 – Base Electrode Wear Experiment 2 - Solid Electrode
96
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
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-4.0
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0.00
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0
8.00
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12.0
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16.0
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20.0
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24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-0.500
-0.400
-0.300
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
0.500
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EB2
Figure A.12 – Base Electrode Wear Experiment 2 - Electroformed Electrode
97
16.0
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12.0
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8.00
0
4.00
0
0.00
0
-4.0
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-8.0
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-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SC1b-c
Figure A.13 – Cone Electrode Wear Experiment 2 - Solid Electrode
98
16.0
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12.0
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8.00
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4.00
0
0.00
0
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-8.0
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000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.600
-0.400
-0.200
0.000
0.200
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0.600
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC2
Figure A.14 – Cone Electrode Wear Experiment 2 - Electroformed Electrode
99
-16.
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000
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0.00
0
4.00
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8.00
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16.0
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-16.000
-10.000
-4.000
2.000
8.00014.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ST1b-c
Figure A.15 – Triangle Electrode Wear Experiment 2 - Solid Electrode
100
-16.
000
-12.
000
-8.0
00
-4.0
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0.00
0
4.00
0
8.00
0
12.0
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16.0
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-16.000
-10.000
-4.000
2.0008.000
14.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ET2
Figure A.16 – Triangle Electrode Wear Experiment 2 - Electroformed Electrode
101
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
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-2.0
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2.00
0
6.00
0
10.0
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14.0
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18.0
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22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-2.000
0.000
2.000
4.000
6.000
8.000
10.000
12.000
14.000
16.000
18.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FB1 b-c
Figure A.17 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Solid Electrode Work Piece
102
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
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-2.0
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2.00
0
6.00
0
10.0
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14.0
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18.0
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22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-2.000
0.000
2.000
4.000
6.000
8.000
10.000
12.000
14.000
16.000
18.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FB2 b-c
Figure A.18 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Electroformed Electrode
Work Piece
103
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
Height (mm)
Length (mm)
Width (mm)
Material Removed FC3 b-c
Figure A.19 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Solid Electrode Work
Piece
104
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
Height (mm)
Length (mm)
Width (mm)
Material Removed FC2 b-c
Figure A.20 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Electroformed Electrode
Work Piece
105
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT2 b-c
Figure A.21 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Solid Electrode Work
Piece
106
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT1 b-c
Figure A.22 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Electroformed
Electrode Work Piece
107
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SB2 c-d
Figure A.23 – Base Electrode Wear Experiment 3 - Solid Electrode
108
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Tool Wear EB3
Figure A.24 – Base Electrode Wear Experiment 3 - Electroformed Electrode
109
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.250
-0.200
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
0.200
0.250
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SC1c-d
Figure A.25 – Cone Electrode Wear Experiment 3 - Solid Electrode
110
16 14 12 10 8 6 4 2 0 -2 -4 -6 -8 -10 -12 -14 -1616.000
10.000
4.000
-2.000
-8.000-14.000
-0.250
-0.200
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
0.200
0.250
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC3
Figure A.26 – Cone Electrode Wear Experiment 3 - Electroformed Electrode
111
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
Heigth (mm)
Length (mm)
Width (mm)
Electrode Wear ST1c-d
Figure A.27 – Triangle Electrode Wear Experiment 3 - Solid Electrode
112
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ET3
Figure A.28 – Triangle Electrode Wear Experiment 3 - Electroformed Electrode
113
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FB1 c-d
Figure A.29 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 3 - Solid Electrode Work Piece
114
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FB2 c-d
Figure A.30 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 3 - Electroformed Electrode
Work Piece
115
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FC3 c-d
Figure A.31 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 3 - Solid Electrode Work
Piece
116
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FC2 c-d
Figure A.32 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 3 - Electroformed Electrode
Work Piece
117
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
Height (mm)
Length (mm)
Width (mm)
Workpiece FT2 c-d
Figure A.33 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 3 - Solid Electrode Work
Piece
118
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
Height (mm)
Length (mm)
Width (mm)
Workpiece FT1 c-d
Figure A.34 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 3 - Electroformed
Electrode Work Piece
119
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SB2 d-e
Figure A.35 – Base Electrode Wear Experiment 4 - Solid Electrode
120
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
Height (mm)
Length (mm)
Width (mm)
Tool Wear EB4
Figure A.36 – Base Electrode Wear Experiment 4 - Electroformed Electrode
121
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SC1 d-e
Figure A.37 – Cone Electrode Wear Experiment 4 - Solid Electrode
122
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.150
-0.100
-0.050
0.000
0.050
0.100
0.150
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC4
Figure A.38 – Cone Electrode Wear Experiment 4 - Electroformed Electrode
123
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.000
-0.500
0.000
0.500
1.000
1.500
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ST1d-e
Figure A.39 – Triangle Electrode Wear Experiment 4 - Solid Electrode
124
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.000
-0.500
0.000
0.500
1.000
1.500
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ET4
Figure A.40 – Triangle Electrode Wear Experiment 4 - Electroformed Electrode
125
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-3.000
-1.000
1.000
3.000
5.000
7.000
9.000
11.000
13.000
15.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FB1 d-e
Figure A.41 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 4 - Solid Electrode Work Piece
126
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-3.000
-1.000
1.000
3.000
5.000
7.000
9.000
11.000
13.000
15.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FB2 d-e
Figure A.42 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 4 - Electroformed Electrode
Work Piece
127
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FC3 d-e
Figure A.43 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 4 - Solid Electrode Work
Piece
128
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FC2 d-e
Figure A.44 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 4 - Electroformed Electrode
Work Piece
129
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
Height (mm)
Length (mm)
Width (mm)
Workpiece FT2 d-e
Figure A.45 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 4 - Solid Electrode Work
Piece
130
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
Height (mm)
Length (mm)
Width (mm)
Workpiece FT1 d-e
Figure A.46 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 4 - Electroformed
Electrode Work Piece
131
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SB1 a-b
Figure A.47 – Base Electrode Wear Experiment 5 - Solid Electrode
132
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
Height (mm)
Length (mm)
Width (mm)
Tool Wear EB5
Figure A.48 – Base Electrode Wear Experiment 5 - Electroformed Electrode
133
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SC2a-b
Figure A.49 – Cone Electrode Wear Experiment 5 - Solid Electrode
134
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC5
Figure A.50 – Cone Electrode Wear Experiment 5 - Electroformed Electrode
135
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ST2a-b
Figure A.51 – Triangle Electrode Wear Experiment 5 - Solid Electrode
136
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ET5
Figure A.52 – Triangle Electrode Wear Experiment 5 - Electroformed Electrode
137
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FB1 e-f
Figure A.53 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 5 - Solid Electrode Work Piece
138
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
Height (mm)
Length (mm)
Width (mm)
Material Removed FB2 e-f
Figure A.54 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 5 - Electroformed Electrode
Work Piece
139
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
Height (mm)
Length (mm)
Width (mm)
Material Removed FC3 e-f
Figure A.55 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 5 - Solid Electrode Work
Piece
140
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
Height (mm)
Length (mm)
Width (mm)
Material Removed FC2 e-f
Figure A.56 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 5 - Electroformed Electrode
Work Piece
141
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-7.000
-5.000
-3.000
-1.000
1.000
3.000
5.000
7.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT2 e-f
Figure A.57 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 5 - Solid Electrode Work
Piece
142
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-7.000
-5.000
-3.000
-1.000
1.000
3.000
5.000
7.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT1 e-f
Figure A.58 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 5 - Electroformed
Electrode Work Piece
143
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-2.500
-2.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SB1 b-c
Figure A.59 – Base Electrode Wear Experiment 6 - Solid Electrode
144
-24.
000
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
24.0
00
-20.000
-12.000
-4.000
4.00012.000
20.000
-2.500
-2.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
Height (mm)
Length (mm)
Width (mm)
Tool Wear EB6
Figure A.60 – Base Electrode Wear Experiment 6 - Electroformed Electrode
145
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.100
-0.080
-0.060
-0.040
-0.020
0.000
0.020
0.040
0.060
0.080
0.100
0.120
Height (mm)
Length (mm)
Width (mm)
Electrode Wear SC2b-c
Figure A.61 – Cone Electrode Wear Experiment 6 - Solid Electrode
146
16.0
00
12.0
00
8.00
0
4.00
0
0.00
0
-4.0
00
-8.0
00
-12.
000
-16.
000
16.000
10.000
4.000
-2.000
-8.000-14.000
-0.100
-0.080
-0.060
-0.040
-0.020
0.000
0.020
0.040
0.060
0.080
0.100
0.120
Height (mm)
Length (mm)
Width (mm)
Electrode Wear EC6
Figure A.62 – Cone Electrode Wear Experiment 6 - Electroformed Electrode
147
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Heigth (mm)
Length (mm)
Width (mm)
Electrode Wear ST2b-c
Figure A.63 – Triangle Electrode Wear Experiment 6 - Solid Electrode
148
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
-16.000
-10.000
-4.000
2.000
8.00014.000
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
0.400
0.600
0.800
Height (mm)
Length (mm)
Width (mm)
Electrode Wear ET6
Figure A.64 – Triangle Electrode Wear Experiment 6 - Electroformed Electrode
149
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FB1 f-g
Figure A.65 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 6 - Solid Electrode Work Piece
150
-26.
000
-22.
000
-18.
000
-14.
000
-10.
000
-6.0
00
-2.0
00
2.00
0
6.00
0
10.0
00
14.0
00
18.0
00
22.0
00
26.0
00
-22.000
-14.000
-6.0002.000
10.00018.000
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
3.000
Height (mm)
Length (mm)
Width (mm)
Material Removed FB2 f-g
Figure A.66 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 6 - Electroformed Electrode
Work Piece
151
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
Height (mm)
Length (mm)
Width (mm)
Material Removed FC3 f-g
Figure A.67 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 6 - Solid Electrode Work
Piece
152
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
Height (mm)
Length (mm)
Width (mm)
Material Removed FC2 f-g
Figure A.68 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 6 - Electroformed Electrode
Work Piece
153
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-6.000
-4.000
-2.000
0.000
2.000
4.000
6.000
8.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT2 f-g
Figure A.69 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 6 - Solid Electrode Work
Piece
154
-20.
000
-16.
000
-12.
000
-8.0
00
-4.0
00
0.00
0
4.00
0
8.00
0
12.0
00
16.0
00
20.0
00
-20.000
-12.000
-4.000
4.000
12.00020.000
-6.000
-4.000
-2.000
0.000
2.000
4.000
6.000
8.000
Height (mm)
Length (mm)
Width (mm)
Workpiece FT1 f-g
Figure A.70 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 6 - Electroformed
Electrode Work Piece