Mini Project for Design of Manufacturing

1

1 Introduction

Nowadays, with the rapid development of technology and the increased in daily

consumption of people, the limited amount of resources in this world had been dropping

in a quick rate and this had put enormous pressure on the environment. As a result, a few

important criteria in designing new product for manufacturing had risen within this

decade and these included: quality and quantity of material used, energy input and carbon

footprint and the ease of assembly. These design criteria could be achieved by following

certain methodologies such as concurrent engineering (CE), computer simulation,

environmental conscious manufacturing (ECM), design for manufacturing (DFM)

material resources planning and lean manufacturing.

Drilling process was a common machining process in industry. When the location and

orientation of the hole machined by the drill needed to be accurate, a drill press was

usually required. A drill press was composed of a base that supported a column which in

turn supported a platform. The work can be supported on the platform with a vise or a

clamp. The height of the platform was adjustable and could also be secured at certain

position along the column by some means of fasteners. This platform was where the drill

was placed or clamped and it was connected with a handle where the operator could exert

a force in order to help the drilling process.

In this design project, a mechanical drill press was analyzed and redesigned in order to

reduce the waste of raw material, cost and energy input, impact on environment and

improve in the rate of assembly.

The requirement of this redesigned drill press was to be manufactured in a quantity of 30,

000 per annum.

2

2 Objectives

The objectives of this project was to improve the original design in terms of cost, energy

and material input, reduced amount of waste material, reduced environmental impact,

increased in assembly rate.

The followings were some of the main objectives of this project:

To analysis the original drill press design and investigate the basic functions and

problems relating to it.

To create or improve the design regarding to financial, social, risk and

environmental aspects.

To investigate the process of manufacturing a product in industry and make

comparisons between the original and new design with the aid of project

management skills.

Make use of the design principles: concurrent engineering, Design for

manufacturing and assembly, Material resource planning environmental conscious

manufacturing and lean manufacturing, etc to redesign the drill press.

3

3 Original drill press design (MK 1)

Table 3.1a: Different projections on original design

Top view

Front view

Side view

4

Detailed analysis was made on the original drill press design and the whole design was

disassembled and each component was analyzed and drawn using Computer simulation:

Solidworks Premium 2010. With the aid of computer simulation, this reduced the cost

and time of producing a prototype during redesigning process and ease of manufacturing

and assembly processes of the original design could be investigated in a much easier way.

Figure 3.1: Isometric view of the original drill press

Base

Handle

Shaft

C-shaped

(Top)

C-shaped

(Middle)

C-shaped

(Bottom)

Cage of roller Rectangular

clamp

Cylindrical

support

Cylinder

B

Cylinder

A

Cylinder

A

Threaded rod

(M8x200)

Drill

clamping bolt

(M10x75)

Hexagonal

Nut (M8)

5

Figure 3.2: Cage of roller connecting with handle

Figure 3.3: Base of the drill press

Figure 3.4: Clamping position of the hand drill

Roller

Washer

(M6)

Handle bolt

(M8x60)

Washer

(M10)

Base Bolt

(M10x16)

Drill clamping

bolt (M10x75)

Hexagonal nut

(M10)

Hexagonal Nut

(M6)

Roller spacer

Handle

spacer

2 screws

(M5x7.5)

6

Table 3.1: Bill of material of original design

Part

number Name of component

Quantity

of part

Volume of

material

(mm3)

Material type

Essential parts

1 Base 1 134673.38 Steel

2 Handle 1 68355.14 Steel

3 Shaft 1 150754.29 Steel

4 C-shaped part (Top) 1 51623.06 Steel

5 C-shaped part (Middle) 1 71158.40 Steel

6 C-shaped part (Bottom) 1 27039.44 Steel

7 Roller 1 2478.72 Steel

8 Cage of roller 1 10335.0 Steel

9 Rectangular clamp 1 36499.51 Steel

10 Cylindrical support 2 1229.23 Steel

11 Cylinder B 1 19738.70 Steel

Total number of essential parts 12

Non-essential parts

12 Cylinder A 2 8055.84 Brass

13 Washer (M6) 1 200.81 Steel

14 Washer (M10) 1 424.77 Steel

15 Threaded rod (M8x199) 1 6344.16 Carbon steel

16 Base bolt (M10x16-14) 1 2833.90 Carbon steel

17 Handle bolt (M8x60x23) 1 1391.95 Carbon steel

7

18 Drill clamping bolt

(M10x75x51.6) 1 4593.19 Carbon steel

19 Hexagonal nuts (M6) 1 348.92 Carbon steel



22 Cylindrical nut 1 3613.27 Steel

23 Cage of roller holding

screw (M5x8.5) 2 432.46 Steel

24 Roller spacer 1 585.28 Brass

25 Handle spacer 1 3613.27 Brass

Total number of non-essential parts 22

Total 34 625431.58

Design efficiency (%) 35.29

3.1 Essential basic functions analysis of the original design

Some of the essential basic features of the original design had to be kept constant

throughout the redesigning process. This could ensure the new design could at least

achieve the minimum required functions of this original product.

The Base of the drill press was to provide stability to the drill press; therefore, it has to be

heavy and its surface areas have to be large enough to achieve this function.

The shaft of the drill press could provide a sliding surface for the C-shaped parts to be

positioned at any required height.

There were two essential functions that had to be achieved by the C-shaped parts: one

was to clamp the hand drill and hold it in position and the other one was to measure the

depth of drill during the drilling operation.

The rectangular clamp provided a way to position the fulcrum point of the handle to

any required height along the shaft.

8

The handle provided a way for the user to exert a force on the C-shaped part which in

turn drove the hand drill into the workpiece.

The roller together with the cage of roller provided a smooth path of the handle to

follow when the user was exerting a force on the C-shaped part through the handle.

The Threaded roll together with the nuts (M8) could adjust the depth of the drilling on

the workpiece and this function had to be kept for the new design.

3.2 Problems with original design

In terms of assembly rate, welding was a manual process and it required a lot of time and

cost. As shown in Figure 3.1 below, the areas circled in red were the points where

welding was required. This showed that the C-shaped parts required a long time for

assembly and manufactured. The original drill press design consisted of many small and

different parts such as various size of nuts, bolt, washers and screw and this would

obviously affect the rate of assembly and not suitable for mass production. As shown in

Figure 3.5, the Threaded rod contained six nuts along its length and the order of

inserting the Rectangular clamp and the nuts on the Threaded rod had to be precise

and this would cause great difficulties to the workers doing the assembly and hence this

slowed down the assembly process. Apart from the Rectangular clamp, the overall

shape of the original design had sharp surface and edges. As it was unsafe for assembly

workers to work with parts with sharp edges, the Rectangular clamp had to be

redesigned.

9

Figure 3.1: Isometric view of the original

drill press

Figure 3.5: Threaded rod with nuts

3.3 Manufacturing process of Product

3.4 Justifications and limitations of data used

A brief explanation of the whole process of manufacturing for both original and new drill

press design would be discussed in the following sections. Starting from which type of

raw material, machining type, machining time, machining cost, labour cost and assembly

cost were explained in detail the following sections.

The total cost of the manufacturing a product included price for raw materials, wages for

the operator, equipment and tooling cost and the assembly cost.

Based on engineering assumptions and information researched, the price of raw material

was assumed based on its overall dimensions with the aid of machining estimator

(Custompart, 2010) online.

10

The time for each machining operation for each component included setting up,

positioning the parts on the machine, operation, collecting the machined parts and

transferring the parts to different machining process. The time for setting up the machine

and the transferring process was assumed to be negligible. The cost of machining process

included electricity for equipments and tooling cost and because of insufficient data

relating to the energy and cost consumed by each tools and equipments, only an average

value for each machining process could be assumed based on engineering knowledge and

knowledge from Industry Technology 343. A detail of expenses such as the overhead

within a factory, tooling costs such as cost of a cutting tools and its tool life, cost of a die

and a mold and the energy consumption for each equipment per annum, etc could not be

provided precisely in this report. In a real Part-manufacturing company, each of them

would have their own catalogue regarding to the cost for different machining process and

the equipment and so the data assumed in calculations in the following sections might be

far from the actual data in industry areas but it could act as a correct guide for the reader

on how to analysis a design.

The time for assembling the part was calculated based on Boothroyd-Dewhurst Method

(Tim, 2010) where relating tables were shown in the Appendix section.

The salary for the operator was based on a normal wage statistic (Migrationexpert, 2010)

in Western Australia as shown in the Appendix and the hourly pay rate for each operator

was AUD 26.12 per hour. The labor cost was calculated by multiplying the total amount

of time the operator spent on the machining process to the salary rate per minutes.

11

3.5 Machining process of each parts of the original design (Mark 1)

The following table showed all the required machining process for the manufacturing of

the original drill press.

Table 3.5.1: Total number and cost of machining process required in the original design

Number Source of cost Cost (AUD/ min)

1 Press brake forming 0.083

2 Punch press forming 0.083

3 CNC machining 0.3

4 Cold sawing 0.1

5 Lathe turning 0.1

6 Lathe drilling 0.1

7 Welding 0.13

8 Belt grinding 0.05

9 Labour cost 0.435

Table 3.5.2a: Schematic diagram of stock material required for original design

Flat sheet

Rectangular bar

Round bar

Round tube

12

Table 3.5.2b: Total cost and amount of stock material needed for unit product

Workpiece Material type Density

(kg/m3)

Dimensions

(mm) Cost (AUD)

Flat sheet Steel-medium

carbon (1040) 7830.00

300x280x2 0.93

440x40x5 0.53

200x70x3 0.24

190x35x3 0.45

150x70x4 0.25

Round bar

Steel-medium

carbon (1040) 7830.00

=20; L=480 0.94

=20; L=26 0.05

=40; L=20 0.31

=16; L=25 0.04

=13; L=11 0.04

=16; L=30 0.16

Brass alloy:360 8500.00 =31; L=25 0.63

Round tube Steel-medium

carbon (1040) 7830.00

=13; T=7;

L=7.5 0.15

Rectangular bar Steel-medium

carbon (1040) 7830.00

32x15x40 0.12

71x40x16 0.28

Total 5.12

13

Table 3.5.3: Manufacturing cost and time for Part 1

Base

Raw material Flat sheet Density

(kg/m3)

Stock

dimensions

(mm)

Price(AUD/kg) Cost (AUD)

Steel-

medium

carbon

(1040)

7830.00 300x280x2 0.79 0.93

Labour 2.82

Machining

Process Time

Punch press

forming 15.00sec 0.02

CNC

Machining 5.00 mins 1.50

Press brake

forming 15.00 sec 0.02

Welding 1.00 min 0.13

Total 6.30min 5.42

Note: Table 3.5.3 was shown as a sample of calculations, all the machining cost and time

for the remaining parts of the original design could be found from the Appendix section.

14

Fasteners of the assembly could be purchased instead of machining, the following table

showed all the required fasteners for the original design.

Table 3.5.15: Specifications of fasteners used in the original design (Boltsnutscrewonline,

2009)

Part Fasteners Designation Quantity Material Price

(AUD)

11 Split washer M6 1 Steel 0.04

12 Washer M10 1 Steel 0.11

13 Threaded rod M8x199 1 High tensile

steel 0.93

14 Base bolt M10x16 1 High tensile

steel 0.10

15 Handle bolt M8x60 1 High tensile

steel 0.38

16 Drill

clamping bolt M10x75 1

High tensile

steel 0.53

17 Hexagonal

nuts M6 1

Galvanized

steel 0.04

18 Hexagonal

nuts M8 6

Galvanized

steel 0.42

19 Hexagonal

nuts M10 1

Galvanized

steel 0.1

21 Screw M5x9.5 2 steel 0.4

Total 16 3.1

15

3.5.1 Analysis of assembly time of the original design

By using Boothroyd-Dewhurst DFA method and the relating Tables shown in Appendix

section, the total assembly time of the original design was shown in the following table.

The whole assembly process was visualised in the Appendix section.

Table 3.5.1.1: Assembly cost and time of original design

Process

number

Part

combination

Handling

code

Handling

time

(sec)

Insertion

code

Insertion

time

(sec)

Total

time

(sec)

1 Base +

Shaft 10 1.5 01 2.5 4

2

Base bolt +

Washer

(M10)

13 2.06 00 1.5 3.56

3

Bolt &

washer +

Shaft

10 1.5 01 2.5 4

4

C-Shaped +

Cylinder A

x2

12 2.25 01 2.5 9.5

5 C-shaped +

Shaft 10 1.5 03 3.5 5

6

Rectangular

clamp +

Shaft

11 1.8 00 1.5 3.3

7

Threaded

rod + C-

shaped (Top

and bottom)

00 1.5 01 2.5 4x2

=8

8

Threaded

rod +

Rectangular

clamp

00 1.5 00 1.5 3

16

9

Threaded

rod +

6 nuts (M8)

00 1.5 11 5 6.5x6

=39

10

Drill

clamping

bolt +

C-shaped

10 1.5 00 1.5 3

11

Drill

clamping

bolt +

2 nuts (M10)

00 1.5 01 2.5 4x2

=8

12

Drill clamp

bolt +

Cylindrical

nut

11 1.8 01 2.5 3.3

13

Cage of

roller +

2 screw

(M5)

11 1.8 11 5 6.8x2

=13.6

14

2 screw

(M5) +

C-shaped

32 2.7 08 6.5 9.2

15 Roller +

Roller spacer 01 1.5 00 1.5 3

16

Roller &

Roller spacer

+

Cage of

roller

11 1.8 00 1.5 3.3

17

Handle

spacer +

Handle

31 2.25 00 1.5 3.75

18 Handle +

Roller 30 1.95 00 1.5 3.45

19

Spilt washer

(M6) +

Roller

13 2.06 00 1.5 3.56

17

20 Roller +

Nuts (M6) 10 1.5 00 1.5 3

21

Handle Bolt

(M8x60) +

Handle

spacer

30 1.95 01 2.5 4.45

22

Handle Bolt

(Mx60) +

Rectangular

clamp

30 1.95 01 2.5 4.45

Total assembly time 145.42

Total assembly cost for worker (AUD) 1.05

18

Table 3.4: Summary of manufacturing process of original design

Environmental aspect

Total volume of material on the design (mm3) 625431.58

Total usage of stock material (mm3) 874863.69

Volume of material on the design without

fasteners (mm3) 606600.41

Total volume of wasted material (mm3) 268263.28

Percentage of waste (%) 30.66

Financial aspect

Total time of machining process (min) 46.41

Total assembly time (min) 2.42

Total time (min) 48.63

Total cost of raw material (AUD) 5.12

Total wage for operators (AUD) 22.02

Total cost of machining process 10.86

Total cost of fasteners (AUD) 3.10

Total assembly cost (AUD) 1.05

Total cost (AUD) 42.15

19

4 New drill press design (MK 2)

Table 4.1a: Different projections on new design

Top view

Front view

Side view

20

Figure 4.1b: Isometric view of the new drill press

Handle

Base

Cylinder

Shaft

T-shaped clamp

Spring

Threaded rod

M8x200

C-shaped

Handle

Hexagonal nut (M8)

21

Figure 4.2: ABS clip opened

Figure 4.3: C-shaped connected with handle

Figure 4.4: Base of the drill press

Handle bolt

(M8x40)

ABS clip

Hinge pin

Socket head

screw (M8x15)

Hinge pin head

Hexagonal nut

(M8)

Base washer

(M8)

Base Bolt

(M8x16)

22

Table 4.1: Bill of material of new design

Part

number Name of component

Quantity

of part

Volume of

material

(mm3)

Material

Essential parts

1 Base 1 134673.38 Recycled steel

2 Handle 1 28893.83 Recycled steel

3 Shaft 1 150754.29 Recycled steel

4 C-shaped 1 117262.67 Recycled aluminum

5 Spring 1 29145.19 Recycled steel

6 Cylinder 1 19738.70 Recycled steel

7 ABS clip 1 6954.13 Thermoplastic

8 Socket head (M8x15) 1 1978.12 Steel

9 T-shaped clamp 1 24623.14 Recycled brass

10 Hinge pin 1 82.79 Steel

Total number of essential parts 10

Non-essential parts

11 Base bolt (M8x16) 1 2275.63 Steel

12 Base washer (M8) 1 1656.40 Steel

13 Threaded rod (M8x200) 1 6344.16 Steel

14 Handle bolt (M8x40) 1 2770.99 Steel

15 Hexagonal nut (M8) 3 2770.99 Steel

16 Hinge pin head 1 17.28 Steel

Total number of non-essential parts 8

Total 18 529746.21

Design efficiency (%) 55.55

23

4.1 Machining process of each parts of the new design (Mark 2)

The following table showed all the required machining process for the manufacturing of

the new drill press.

Table 4.1.1: Total number and cost of machining process required in the new design

Number Source of cost Cost (AUD/ min)

1 Press brake forming 0.083

2 Punch press forming 0.083

3 CNC machining 0.3

4 Cold sawing 0.1

5 Lathe turning 0.1

6 Lathe drilling 0.1

7 Lathe milling 0.1

8 Permanent mold casting 0.2

9 Thermoforming 0.1

10 Welding 0.13

10 Labour cost 0.435

Table 4.1.2: Schematic diagram of stock material required for new design

Flat sheet

Rectangular bar

Round bar

Round tube

24

Table 4.1.3: Required cost and amount of stock material needed for unit product for new

design

Workpiece Material type Density

(kg/m3)

Dimensions

(mm) Cost (AUD)

Flat sheet

Recycled steel-

medium carbon

(1040)

7830.00

300x280x2 0.93

305x22.5x5 0.20

Acrylonitrile

Butadiene

Styrene

1100.00 63x22.5x5 0.02

Round bar Recycled steel-

medium carbon

(1040)

7830.00 =20; L=480 0.94

Round tube Recycled steel-

medium carbon

(1040)

7830.00

=40; T=10;

L=21 0.12

Rectangular bar Recycled brass

alloy: 360 8500.00

40x60x22.5 1.43

Total 3.64

25


C-shaped


(kg/m3)

Stock

volume

(mm3)


Recycled

Aluminium

356.0 T7

2679.00 117223.77 2.09 0.66

Labour 2.17

Envelope (X×Y×Z) (mm) 160×250×26

Projected area (mm2) 9045

Tooling Permanent mold 0.67

Production Time

Casting 5.00 min 1.00

CNC

Machining 1 min 0.3

Total 5.00 min 4.50

Note: Table 4.1.4 was shown as a sample of calculations, all the machining cost and time

for the remaining parts of the new design could be found from the Appendix section.

The material cost included the cost of the metal in current market. These costs were

estimated from the part geometry and use up-to-date material prices. The production cost

included the cost of melting the metal, making the molds and cores, pouring the metal,

and removing and cleaning the castings. The production and labor rates for these

operations were assumed as the same as other machining process. For the tooling cost,

the cost of both the pattern and the core-boxes were estimated in a variety of materials,

and the optimal choice was provided.

26

Fasteners used in the assembly could be purchased instead of machining, the following

table showed all the required fasteners for the new design.

Table 4.1.11: Specifications of fasteners used in the new design (Boltsnutscrewonline,

2009)

Part Fasteners Designation Quantity Material Price

(AUD)

8 Socket head M8x15 1 High tensile

steel 0.15

10 Hinge pin M2 1 Steel 0.1

11 Base bolt M8x16 1 High tensile

steel 0.14

12 Base washer M8 1 Steel 0.1

13 Threaded rod M8x200 1 High tensile

steel 0.93

14 Handle bolt M8x40 1 High tensile

steel 0.2

15 Hexagonal

nut M8 3

High tensile

steel 0.3

16 Hinge pin

head - 1 Steel 0.1

Total 10 2.02

Spring used in the assembly could be purchased instead of machining, the following table

showed specifications of the spring used in the new design.

Table 4.1.12: Specifications of the spring used in new design (Ashfield spring, 2010)

Material Carbon steel

Outer diameter (mm) 35

Inner diameter (mm) 20

Wire diameter (mm) 7.5

Free length (mm) 100

Solid height (mm) 42.5

Spring rate (N/mm) 3.63

Price (AUD) 2.87

27

4.1.1 Analysis of assembly time of the new design

By using Boothroyd-Dewhurst DFA method and the relating Tables shown in Appendix

section, the total assembly time of the new design was shown in the following table. The

whole assembly process was visualised in the Appendix section.

Table 4.1.1.1: Assembly cost and time of the new design

Process

number

Part

combination

Handling

code

Handling

time

(sec)

Insertion

code

Insertion

time

(sec)

Total

time

(sec)

1 Base + Shaft 10 01 1.5 2.5 4

2

Base bolt +

Washer

(M8)

13 2.06 00 1.5 3.56

3

Base bolt &

Washer +

Shaft

10 1.5 01 2.5 4

4 C-shaped +

Shaft 00 1.5 01 2.5

4x2

=8

5

T-shaped

clamp +

Shaft

00 1.5 00 1.5 3

6 Spring +

Shaft 00 1.5 00 1.5 3

7 Hinge pin +

ABS Clip 03 2.18 00 1.5 3.68

8 Hinge pin +

C-shaped 03 2.18 00 1.5 3.68

28

9

Hinge pin +

Hinge pin

head

03 2.18 00 1.5 3.68

10

Threaded

rod

(M8x200) +

Hexagonal

nut (M8) x2

00 1.5 01 2.5 4x2

=8

11

Threaded

rod

(M8x200) +

C-shaped

00 1.5 00 1.5 3

12

Socket head

(M8x15) +

Handle

31 2.25 00 1.5 3.75

13

Socket head

(M8x15) +

C-shaped

31 2.25 01 2.5 4.75

14

Handle bolt

(M8x40) +

T-shaped

30 1.95 01 2.5 4.45

15

Handle +

Handle bolt

(M8x40)

30 1.95 00 1.5 3.45

16

Handle bolt

(M8x40) +

Hexagonal

nut (M8)

30 1.95 01 2.5 4.45

Total assembly time 68.45

Total assembly cost for worker (AUD) 0.49

29

Table 4.2: Summary of manufacturing process of new design

Environmental aspect

Total volume of material on the design (mm3) 529746.21

Total usage of stock material (mm3) 551212.24

Volume of material on the design without

fasteners and spring (mm3) 482900.14

Total volume of wasted material (mm3) 68312.10

Percentage of waste (%) 12.39

Financial aspect

Total time of machining process (min) 30.10

Total assembly time (min) 1.14

Total time (min) 31.24

Total cost of raw material (AUD) 4.30

Total wage for operators (AUD) 12.68

Total cost of machining process 6.70

Total cost of fasteners & spring (AUD) 4.89

Total assembly cost (AUD) 0.47

Total cost (AUD) 30.06

30

5 Discussion

5.1 Comparison and analysis between old design (Mark 1) and new

design (Mark 2)

5.1.1 Discussion and explanation on new Handle design

The material used, thickness and the overall dimensions of the new handle did vary a lot

from the old design. A new slot was created on the new handle so that a M6 socket head

screw connecting to the C-shaped could slide along in it. This design eliminated the

needed of extra parts in the old design such as the Roller, Cage of roller and the Roller

spacer. The machining time for this new design was longer than the old one because of its

increased in number of bends required but in return this design improved the ease of

assembly which in turn reduced the assembly time. The number of parts in the whole

assembly were reduced, thus the cost and time for manufacturing were reduced. Less

material waste was resulted and the impact on environment could be reduced.

Table 5.1.1.1: Comparison of specifications between old and new handle design

Old New

Material type Steel-medium carbon

(1040)

Recycled steel-medium

carbon (1040)

Stock dimension (mm) 440x40x5 305x22.5x5

Actual volume of material

on part (mm3) 68355.14 28893.83

Waste of material (%) 22.32 15.79

Machining time (min) 3.5 4

Cost (AUD) 2.99 2.9

31

Side view Side view

Top view Top view

Figure 5.1.1.1a: Old Handle design Figure 5.1.1.1b: New Handle design

5.1.2 Discussion and explanation on new C-shaped design

5.1.2.1 C-shaped

The old design of C-shaped required a lot of welding process and because the geometry

of this design, automated welding was not possible. Welding was a manual process which

required a lot of time and cost. It was unsuitable for mass production of product.

In the new design, permanent mold casting was used to manufacture this part. A

permanent mold needed to be created at the beginning of the casting process.

Characteristics of permanent mold casting process could be found in Section 8.7 in

Appendix. A permanent mold typical cost about AUD 20,000 (Kruse, 2006) which when

divided by the number of part required (30,000) would result in about AUD 0.67 per part.

This permanent mold would be considered as a high tooling cost only if quantity of part

was low. For this project, the required quantity of part was 30,000 parts per annum and

this could be reason to justify the use of a permanent mold. Permanent mold casting was

suitable for aluminum and it had low to moderate tooling lead time, casting lead time,

casting cost and finishing cost (Kruse, 2006). The cost material that used create internal

structure of the product was grey iron. The advantages of permanent mold casting were

32

good surface finished and tolerance of product and high production rate. The main

disadvantage of permanent mold casting was high equipment and tooling cost for low

quantity of production. By using this kind of casting method, this reduced the number of

the parts of the design, increased in rate of assembly, reduced in wastage material and the

energy input for the overall process. Together with the fact that 30,000 product needed to

be manufactured per annum, these factors could be the reasons to justify the use of this

high tooling-cost casting method.

Because of the difference in manufacturing process, the new C-shaped could be

manufactured in one piece instead of having 3 sheets of metal plated welded manually

together and 2 brass cylinder inserted manually. This resulted in a great decreased in

assembly time and wastage of material. Since casting was used, all the scrap material

could be collected and melted. This recycled all the wastage material, hence keeping the

waste of material to minimum level. Since the assembly time and material usage were

reduced, this resulted in a decrease in cost of each part.

The casting process was briefly explained as followings: the machining time shown in

Table 4.1.4 only included the casting period. This was because workers from one shift

would be responsible for pouring the molten metal into the mold and worker from

another shift would be responsible for collecting the cast and performed secondary finish

and machining processes. The cooling period of casting was not considered since after all

the required amount of molten metal was poured, the workers could move on and worked

on another parts of the product. This could result in a decrease in labor cost as well.

The material for the C-shaped was recycled aluminum while the material for the shaft

was recycled steel. As the C-shaped had to slide along the shaft; therefore two different

materials had to be used for these two parts or else the C-shaped could be worn out easily.

Since in the input material for the C-shaped was recycled aluminum; therefore, even after

the C-shaped finally worn out and needed replacement, the C-shaped could be sent to

recycling plant and this would not create any impact on the environment.

5.1.2.2 ABS clip

As shown in Figure 6.1.2.1b, a clip made of ABS (Acrylonitrile Butadiene Styrene) was

introduced to the new design. In the old design, a Drill clamping bolt together with the C-

33

shaped were required to hold the hand drill in position. By introducing this clip design,

this eliminated unnecessary parts, thus increasing assembly time and reduced material

used. Also, by using this integrated clip design, this reduced the use of an extra fastener.

The clip design could be opened and closed like a door hinge depending on the need of

the user. The clip of ABS which was made up of thermoplastic which was recyclable

which meant that at the end of product lifetime, this ABS material could be recycled

again. This reduced the impact on environment. Since ABS was a kind of thermoplastic,

it possessed certain amount of flexibility and good wear resistance compared to steel. It

had a Young’s modulus value 2x109 Pa comparing to the Young’s modulus of steel

which was 2.04x1011 Pa, this ABS clip was considered as strong enough for its

application.

The size of the ABS clip was designed to fit a hand drill of diameter of 20 mm with ±2

mm flexibility. This ensured that the current type of hand drill fitting on the original

design could be fixed on the new design as well. This ensured that basic essential

function of the drill press was kept constant.

The process required for manufacturing thermoplastic was pressure forming of

thermoforming. The starting raw material was a thermoplastic sheet. The advantages of

thermoforming were high production rate and low cost while its disadvantages were the

limited complexity of the design and trimming was required (Custompart, 2010). Since

the geometry of the clip was very simple, this disadvantage did not really affect the

design.

Table 5.1.2.1: Comparison of specifications between old and new C-shaped design

Old New


(1040)

Recycled aluminium 356.0

T7

Total amount of raw

material needed (mm3) 200102.09 124316.87

Waste of material (%) 15.38 1-2

Machining time (min) 14.18 7.10

Cost (AUD) 13.82 5.24

34

Side view Side view

Top view Top view

Hand drill clamping postion Hand drill clamping clip

Figure 5.1.2.1a: Old C-shaped design Figure 5.1.2.1b: New C-shaped design

35

5.1.3 Discussion and explanation on new T-shaped clamp design

The functionality of the new T-shaped clamp remained the same as the old Rectangular

clamp design which was to provide a fulcrum point for the Handle to rotate. The main

difference was that all the sharp edged corners were changed to smooth fillet surfaces.

This increased the percentage of wastage material to 54.40 % which was not very

environmental friendly. However, sharp edges were considered stress raisers and would

increase stress concentration. Also, the sharp edges were unsafe for workers who were

responsible for assembly process. But the overall material needed for this part was

reduced compared to the old design. The scrap material could be collected after the

machining process and recycled for other purposes.

Table 5.1.3.1: Comparison of specifications between old and new clamp design

Old New


(1040) Recycled Brass alloy: 360

Stock dimension (mm) 71x40x16 40x60x22.5

Actual volume of material

on part (mm3) 36499.51 24623.14

Waste of material (%) 19.67 54.40

Machining time (min) 8.10 8.10

Cost (AUD) 6.25 8.87

Top view

Top view

36

Side view

Side view

Figure 5.1.3.1a: Old rectangular clamp

design Figure 5.1.3.2b: New T-shaped design

5.2 Facts comparison between new drill press (Mark 2) and old drill

press (Mark 1)

By analyzing the data shown in the Table 3.4 and Table 4.2, it could be observed that the

total amount of time required for manufacturing the new design dropped from 48.63 min

to 31.24 min and the cost dropped from AUD 42.15 to AUD 30.06. The main reason for

this was because of the decreased in number of parts of the whole assembly. The old

design possessed 34 individual parts while the new design only had 18 parts. The design

efficiency between old and new design improved from 35.29% to 55.55%. The reason for

that was because a lot of unnecessary parts were eliminated or combined into a single

part. This simplicity of the new design had a great impact on the rate of assembly. The

new assembly time was 1.14 min while the old design required 2.42 min.

A lot of environmental friendly materials were introduced to the new design. The new

design made use of a lot of recycled material and thermoplastic which both processed less

carbon footprint and this resulted in less harmful effect on the environment. As shown in

Table 3.4 and Table 4.2, the wastage material between the old and new design dropped

from 30.66% to 12.39%. The reason for this was that apart from traditional machining

processes, permanent mold casting and thermoforming were also used. These processes

might have a higher tooling and equipment cost but in return the raw materials could be

utilized as much as possible. For example, the scrap material resulted from CNC

machining could melted into molten metal again and used in casting process. The total

volume of material used in the old design was 625431.58 mm3 while the one for new

design was 529746.21 mm3. The decreased in amount of material used was 15.29% thus

37

less material was required for manufacturing the product. This reduced the extraction of

virgin material from the environment.

The machining cost between old and new design dropped from AUD 10.86 to AUD 6.70.

The machining cost represented the energy input such as electricity of equipment and

tooling cost. This 38.31% reduction in cost showed that the energy input for

manufacturing the new design was lower than the old design.

The only cost item that increased compared to the old design was the cost for fasteners

and spring. This was because a spring was introduced to the new design which the old

design did not have. Because of the present of this new spring, a lot of unnecessary

fasteners in the old design were eliminated. Apart from the spring, total number of

fasteners between the old and new design dropped from 16 to 10 and this improved the

ease of assembly.

5.3 Functions comparison between new drill press (Mark 2) and old

drill press (Mark 1)

First, the base of the new drill press remained unchanged. The base of the original drill

press was considered as a footprint and provided stability for the drill press. Since the

base remained unchanged, it could be ensured that the stability of the new design must be

as good as the old one. As the base remained unchanged it became the only part and

locations of the whole assembly that required welding process. Comparing this fact with

the old design which required a lot of more locations of welding, this could increase the

rate of assembly and cost input for the new design.

The shaft of the new drill press remained unchanged and its function was still to provide

sliding movement for the C-shaped along itself.

The C-shaped from the new design was responsible for clamping the hand drill with its

new introduced clip and the Threaded rod and the nuts (M8) were also kept in place in

order to measure the depth of the drill similar as the old design. Therefore, these two

essential original functions could also be achieved by the new design as well. Other than

that, a new Spring part was introduced to provide an extra recoil force to help the user to

38

pull back the drill from the workpiece. This was considered as a new function from the

new design.

The rectangular clamp was modified into a T-shaped clamp with a smoother surface to

reduce stress concentration and improved in safety for assembly workers. Its function

remained the same which was to provide a fulcrum point for the handle to rotate.

The handle for the new design was still to provide a mean for the user to exert a force to

assist the drilling process. But in the new design, instead of using several parts such as

roller, cage of roller and the roller spacer, a M8 socket was used and it could slide along

the slot created on the handle. This could reduce the number of parts for the new

assembly.

Figure 5.3a: Old drill press design Figure 5.3b: New drill press design

39

5.4 Functionality of the new Spring part

The primary function of the new Spring was to support and keep C-shaped and the T-

shaped clamp apart before the start of any drilling operation. It provided a recoil action to

help the user to withdraw the drill from the workpiece. The total available depth of drill

of the old design was about 140 mm and this had been considered in the new design also.

This could be done by taking the thickness of the T-shaped clamp and the compressed

length of the Spring itself into account and worked out the lengthof overall height of the

C-shaped.

The Spring specifications were shown in Table 4.1.12 and the spring rate which was

usually known as spring stiffness was calculated by assuming a normal hand drill

weighting at 1.5 kg together with the weight of the C-shaped acting on the spring. Full

calculation was shown in Appendix section. Results showed that by having a spring rate

of 3.63 N/mm and a deflection of 5 mm, this Spring would have enough force to support

the whole structure without any external help. Hence, by knowing all of its specifications,

the spring could be purchased from online supplier (Ashfield spring, 2010).

Figure 5.3.1a: Default length position of

the spring

Figure 5.3.1b: Compressed length position

of the spring

40

5.5 Design Methodology

5.6 Concurrent Engineering

The redesigning process of the drill press was mainly based on the strategies from

concurrent engineering. Feedbacks and comments needed to be collected between design,

manufacturing and product use.

The factors considered during the redesigning process included aesthetic factor, product

performance factors, safety considerations for both workers and customers, maintenance

considerations, quantity needed to be produced, product life, the working environment of

this product and the weight and complexity of the product.

For example, by inspecting the old design, a lot of problems such as too many welding

procedures were required, too many fasteners with different sizes, number of parts and

sharp edges were found. The parts from old design had difficulties in manufacturing. By

getting feedback from manufacturing areas, the product specifications could be

redesigned according to the ease and the selection of manufacturing process. New

concepts and detail design could be proposed in order to improve the ease manufacturing

process. Better selection of material could also be achieved by looking at the impact of

the product on the environment. The benefits resulted from the use of principal of

concurrent engineering were reduced in assembly time (from 2.42 min to 1.14 min),

decreased in production cost (AUD 42.16 to AUD 30.06), reduced in wastage material

(30.66 % to 12.39 %) and reduced in number of parts (34 to 18).

5.7 Design for manufacturing (DFM)

The design cycle for this new drill press included conceptual design, detail design,

manufacturing and product support. In conceptual design, analysis was made on the old

design such as value analysis and functional analysis. Problems such as sharp edges,

excessive use of fasteners and complexity in assembly and manufacturing process were

identified. In detail design was where lists of required raw material was made, selection

of environmental friendly material and manufacturing process was carried out and detail

drawings using computer simulations was created. Finally, in manufacturing stage,

41

production planning strategies such as lean manufacturing and material requirement

planning was made to reduce cost and inventories.

5.7.1 Design for assembly (DFA)

A large number of parts were cut down from the old design, the number of part dropped

from 34 to 18. This reduction in number of parts greatly decreased the assembly time.

Also welding was a manual process and it required skilled worker so the number to

welding process was restricted only for the manufacture of the base of the new drill press.

This reduced a great amount of assembly time.

All the parts such as C-shaped and T-shaped clamp were designed to have a symmetric

shape and smooth surface and easy to handle so that it would be easily for workers to

assembly them since the direction of insertion of parts would be the same in any

directions if it was symmetrical.

Integrated clip was introduced instead of fasteners for the clamping area for the hand drill.

The number of fasteners used in the new design was 10 while the one for the old design

was 16. The new drill press was designed to have less fasteners and this improved the

ease of assembly. Also, the variation of fastener size of the new design was less than the

old one. Less bolt, screws and nuts were used and the sizes only consisted of M6 and M8

for the new design. This would help the workers to easily locate the required size

fasteners during assembly.

The new C-shaped was considered to be the most important part of the whole design as it

was responsible for clamping the hand drill and pushed it into the workpiece. The weight

of the C-shaped dropped from 1.33 kg to 0.3 kg between the old design and new design.

This was because of the use of lighter material, Aluminum; therefore, it would be easier

for the worker to handle a light part than heavier one during assembly process.

42

5.8 Environmental conscious manufacturing (ECM)

5.8.1 Design for environment (DFE)

All the source of raw material used was chosen to be with recyclable content such as

recycled aluminum, recycled steel, recycled brass and thermoplastic. Starting with virgin

material with recyclable content greatly reduced the impact on environment since

extraction of new natural resources was unnecessary. By using product lifecycle

assessment on the new design, all the material used on the new design could be recycled.

Wastage material could be greatly reduced and a “cradle to cradle” product lifespan for

each parts of the new design could be achieved.

The new machining process introduced to the new design compared to that of the old one

was permanent mold casting and thermoforming. Even though the initial cost for

permanent mold casting was high, this could be justified for fact of mass production.

Because of casting process, all the scraps metal that lost in the machining processes could

be collected, melted and reused again. This helped to reduce a great amount of waste

material. By introducing the new material type, thermoplastic which was recycled

compared to thermosets, no matter it was for maintenance, repair or recycle at the end of

its product life, this was a environmental friendly material which would not bring any

harmful effect on the nature.

With the help of Design of environment strategy, the percentage of wastage of material

dropped from 30.66 % to 12.39 %.

5.9 Material requirement planning (MRP)

By using material requirement planning principal, a list bill of material (BOM) as shown

in Table 4.1 and Table 4.1.3 were created for new design. These bills of material helped

to plan and control the acquisition of materials and the process of production. All the

required amount of stock regarding to their size, quantity and their type of material were

planned before any ordering of material started. This helped to control the waste of

material and kept the inventories level to a minimum level.

43

5.9.1 Lean production

For most production operations, only a small fraction of the total time and effort actually

added value in the product for the customer. By eliminating this usefulness energy and

cost input during manufacturing process, a large amount of saving could be achieved and

impact on environment could be reduced as well. The main benefits of using lean

manufacturing process was to save labor, cost, inventory and time. A large amount of

wastage material could be reduced and the speed of the operation could be increased as

well.

By implementing lean manufacturing strategy for the manufacturing of the production of

new design, several areas were improved:

A pull production system would be used. Only the required quantity of virgin material

depending on the orders from customers would be ordered and processed into products.

Unnecessary raw material or parts would not be produced and also when a part moved to

a production operation, was processed immediately, and move immediately to the next

operation. This ensured that the build-up of stock inventories was maintained to

minimum or zero in the warehouse.

As a pull production reduced inventories, equipment breakdowns could be reduced as

well. Properly trained operators were assigned primary responsibility for basic

maintenance since they were in the best position to detect signs of malfunction of the

equipment.

Machining processes and transportation on raw material were restricted or minimized to

essential ones only, this ensured that there would not be any time delays, delay in

material handling, idle time or unnecessary handling on parts.

By applying appropriate training on workers, they could participate in housekeeping,

quality inspection, minor equipment repair, rework, trouble shooting and problem solving

to improve quality and eliminate wastes. Since the quantity of production was in small

batch, faulty products could be found easier. As a result, better quality of products could

be produced (Free-business e-coach, 2010).

44

By applying lean manufacturing strategy, there were several benefits that could be

achieved:

Waste reduction by 80%

Production cost reduction by 50%

Manufacturing cycle times decreased by 50%

Labor reduction by 50% while maintaining or increasing throughput

Inventory reduction by 80% while increasing customer service levels

Capacity in current facilities increase by 50%

Higher quality

Improved cash flow through increasing shipping and billing frequencies

6 Conclusion

In conclusion, a drill press was redesigned successfully with the help of different design

methodologies such as concurrent engineering, design for manufacturing, environmental

conscious manufacturing, design for assembly, lean manufacturing and computer

simulation process. The results from using these methodologies were increased in

assembly rate, reduced in usage of material and wastage material and reduced in energy

and cost input. Therefore, the new design was suitable for a mass production with

quantity of 30,000 per annum.

45

7 Reference list

1. Ashfield spring, 2010. Compression spring. http://www.ashfield-

springs.com/index.html (Assessed 29th October, 2010)

2. Boltsnutscrewonline, 2009. http://www.boltsnutsscrewsonline.com/ (Assessed

29th October, 2010)

3. Custompart, 2010. Machining cost estimator.

http://www.custompartnet.com/estimate/machining/ (Assessed 29th October, 2010)

4. Free-business e-coach, 2010. Lean production.

http://www.1000ventures.com/business_guide/lean_production_main.html

(Assessed 29th October, 2010)

5. Kruse, S. 2006. Engineered casting solution.

http://www.metalcastingdesign.com/images/stories/castingbasics/processes/selecti

ngaprocess.pdf (Assessed 29th October, 2010)

6. Migrationexpert, 2010. Australian working condition and wage.

http://www.migrationexpert.com/australia/visa/australian_working_conditions_an

d_wages.asp (Assessed 29th October, 2010)

7. Tim, S. 2010. Lecture 3: Design for Assembly/Disassembly.

http://wiki.mech.uwa.edu.au/upload/3/38/MECH4403_Lecture_3_DFA.pdf

(Assessed 29th October, 2010)

8 Appendix

http://www.metalcastingdesign.com/images/stories/castingbasics/processes/selectingaprocess.pdf

http://www.metalcastingdesign.com/images/stories/castingbasics/processes/selectingaprocess.pdf

46

8.1 Tables

Figure 8.1.1: Manual handling code for assembly process (Tim, 2010)

Figure 8.1.2: Insertion code for assembly process (Tim, 2010)

8.2 Machining cost of each part of the original design

47


Handle


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 440x40x5 0.79 0.53

Labour 1.52

Machining

Process Time

Punch press


CNC


Press brake


Total 3.30 min 2.99


Shaft

Raw material Round bar Density

(kg/m3)

Stock

dimensions

(mm)

Price(/kg) Cost (AUD)

Steel-

medium

carbon

(1040)

7830.000 20 ;L=480 0.79 0.940

Labour 0.910

Machining

Process Time

Cold sawing 5.000 sec 0.008

Lathe turning 2.000 mins 0.200

Total 2.050 min 2.058

Table 3.5.6a: Manufacturing cost and time for Part 4

C-shaped part (Top)

48


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 200x70x3 0.79 0.24

Labour 1.52

Machining

Process Time

Punch press


CNC


Press brake


Total 3.30 min 3.30

Table 3.5.6b: Manufacturing cost and time for Part 5

C-shaped part (Middle)


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 190x135x3 0.79 0.45

Labour 0.65

Machining

Process Time

Punch press


Drilling 1.00 mins 0.1

Press brake


Total 1.30 min 1.24

Table 3.5.6c: Manufacturing cost and time for Part 6

C-shaped part (Bottom)

49


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 150x70x4 0.79 0.25

Labour 1.41

Machining

Process Time

Punch press


CNC

machining 3.00 mins 0.90

Total 3.15 min 2.58

Table 3.5.6d: Manufacturing cost and time for Part 10

Cylindrical support

Raw material Round tube Density

(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00

=13

T=3

L=7.5

0.79 0.15

Labour 0.36

Machining

Process Time


Grinding belt 30.00 sec 0.03

Total 0.50 min 0.56

Table 3.5.6: Total manufacturing cost and time for sub-assembly of C-shaped parts

Assembly of C-shaped parts

50

Process Time Cost (AUD)

Machining of C-

shaped part (Top) 3.30 min 1.50

Machining of C-

shaped part (Middle) 1.30 min 1.24

Machining of C-

shaped part (Bottom) 3.15 min 2.58

Machining of

cylindrical supports 0.50 min 0.56

Welding of assembly

parts 3.00 min 0.90

Labour 5.25

Total 12.08 min 12.03


Roller


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 =20

L=26 0.79 0.05

Labour 2.28

Machining

Process Time



Total 5.15 min 2.86


51

Cage of roller

Raw material Rectangular

bar

Density

(kg/m3)

Stock

dimensions

(mm)


Steel-medium

carbon (1040) 7830.00 32x15x40 0.79 0.12

Labour 2.24

Machining

Process Time


CNC

machining 5.00 mins 1.5

Total 5:10 min 3.88


Rectangular clamp


bar

Density

(kg/m3)

Stock

dimensions

(mm)


Steel-medium

carbon (1040) 7830.00 71x40x16 0.79 0.28

Labour 3.55

Machining

Process Time


CNC

machining 8 mins 2.4

Total 8.10 min 6.25


52

Cylinder A x2


(kg/m3)

Stock

dimensions

(mm)


Brass

alloy:360 8500.00

=31

L=25 3.14 0.63

Labour 0.94

Machining

Process Time


Lathe drilling 1.00 min 0.10

Lathe turning 1.00 min 0.10

Total 2.10 min 1.79


Cylinder B


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 =40

L=20 0.79 0.31

Labour 0.47

Machining

Process Time


Lathe drilling 30.00 sec 0.05

Lathe turning 30.00 sec 0.05

Total 1.05 min 0.9

Table 3.5.12: Manufacturing cost and time for Part22

53

Cylindrical nut


(kg/m3)

Stock

dimensions

(mm)


Steel-

medium

carbon

(1040)

7830.00 =16

L=25 0.79 0.04

Labour 0.94

Machining

Process Time



Lathe turning 1.00 min 0.10

Total 2.10 min 1.2


Roller spacer


(kg/m3)

Stock

dimensions

(mm)


Brass

alloy:360 8500.00

=13

L=11 3.14 0.04

Labour 0.54

Machining

Process Time



Total 1.15 min 0.71


54

Handle spacer


(kg/m3)

Stock

dimensions

(mm)


Brass

alloy:360 8500.00

=16

L=30 3.14 0.16

Labour 0.97

Machining

Process Time

Cold sawing 15 sec 0.03

Lathe drilling 1 min 0.1

Lathe turning 1 min 0.1

Total 2.15 min 1.36

8.3 Assembly process of the original design

55

Base + Shaft

Base bolt + Washer (M10)

Bolt & washer + Shaft

56

C-shaped + Cylinder A x2

C-shaped + Shaft

Rectangular clamp + Shaft

57

Threaded rod + C-shaped (Top and bottom)

Threaded rod + Rectangular clamp

Threaded rod + 6 nuts (M8)

58

Drill clamping bolt + C-shaped

Drill clamping bolt + 2 nuts (M10)

59

Drill clamp bolt + Cylindrical nut

Cage of roller 2 + screw (M5)

2 screw (M5) + C-shaped

60

Roller + Roller spacer

Roller & Roller spacer + Cage of

roller

Handle spacer + Handle

61

Handle + Roller

Spilt washer (M6) + Roller

Roller + Nuts (M6)

62

Handle Bolt (M8x60) +

Handle spacer

Handle Bolt (Mx60) +

Rectangular clamp

Assembly finished

63

8.4 Machining cost of each part of the new design


Base


(kg/m3)

Stock

dimensions

(mm)


Recycled

steel-

medium

carbon

(1040)

7830.00 300x280x2 0.79 0.93

Labour 2.82

Machining

Process Time

Punch press


CNC


Press brake


Welding 1.00 min 0.13

Total 6.30min 5.42


Handle


(kg/m3)

Stock

dimensions

(mm)


Recycled

steel-

medium

carbon

(1040)

7830.00 305x22.5x5 0.79 0.20

Labour 1.74

Machining

Process Time

Punch press


64

CNC


Press brake


Total 4.00 min 2.90


Shaft


(kg/m3)

Stock

dimensions

(mm)


Recycled

steel-

medium

carbon

(1040)

7830.000 20 ;L=480 0.790 0.940

Labour 0.910

Machining

Process Time



Total 2.050 min 2.058


Cylinder B


(kg/m3)

Stock

dimensions

(mm)


Recycled

steel-

medium

carbon

(1040)

7830.00

=40;

T=10;

L=21 0.79

0.12

Labour 0.11

Machining

Process Time


65

Lathe drilling 5.00 sec 0.02

Lathe turning 5.00 sec 0.02

Total 15.00 sec 0.29


ABS clip


(kg/m3)

Stock

dimensions

(mm)

Price(AUD/kg) Cost

(AUD)

Acrylonitrile

Butadiene

Styrene

1100.00 63x22.5x5 2.81 0.02

Labour 0.51

Machining

Process Time

Thermoforming 1.00 min 0.10

Lathe milling 5.00 sec 0.01

Total 1.10 min 0.64


T-shaped clamp


bar

Density

(kg/m3)

Stock

dimensions

(mm)


Recycled

Brass alloy:

360

8500.00 40x60x22.5 3.14 1.43

Labour 4.42

Machining

Process Time


CNC

machining 10 mins 3.00

Total 8.10 min 8.87

66

8.5 Assembly process of the new design

Base + Shaft

Base bolt + Washer (M8)

Bolt & washer + Shaft

67

C-shaped + Shaft

T-shaped clamp + Shaft

Spring + Shaft

68

Hinge pin +

ABS Clip

Hinge pin +

C-shaped

Hinge pin +

Hinge pin head

69

Threaded rod

(M8x200) +

Hexagonal nut (M8) x2

Threaded rod

(M8x200) +

C-shaped

Socket head (M8x15)

+

Handle

70

Socket head (M8x15) +

C-shaped

Handle bolt (M8x40) +

T-shaped

Handle +

Handle bolt (M8x40)

71

Handle bolt (M8x40) +

Hexagonal nut (M8)

Assembly finished

72

8.6 Calculation of spring rate

Figure 8.6.1: Schematic diagram for spring mass system

By using the following equation,

KxF (Eq 8.6.1)

By assuming a deflection of 5 mm,

)5(81.98.1 K

mmNK /53.3

The spring rate of 3.63 N/mm was chosen as it was the closest value that could be chosen

from online catalogue.

MASS= Hand drill (1.5 kg) + C-

shaped (0.3 kg)

73

8.7 Permanent mold casting

Permanent mold casting is a metal casting process that shares similarities to both sand

casting and die casting. As in sand casting, molten metal is poured into a mold which is

clamped shut until the material cools and solidifies into the desired part shape. However,

sand casting uses an expendable mold which is destroyed after each cycle. Permanent

mold casting, like die casting, uses a metal mold that is typically made from steel or cast

iron and can be reused for several thousand cycles (Custompart, 2010).

Permanent mold casting is typically used for high-volume production of small, simple

metal parts with uniform wall thickness. Non-ferrous metals are typically used in this

process, such as aluminum alloys, magnesium alloys, and copper alloys.

Figure 8.7.1: Schematic diagram of permanent mold casting (Custompart, 2010)

The permanent mold casting process consists of the following steps:

1. Mold preparation - First, the mold is pre-heated to around 300-500°F (150-260°C) to

allow better metal flow and reduce defects. Then, a ceramic coating is applied to the

mold cavity surfaces to facilitate part removal and increase the mold lifetime.

74

2. Mold assembly - The mold consists of at least two parts - the two mold halves and any

cores used to form complex features. Such cores are typically made from iron or steel,

but expendable sand cores are sometimes used. In this step, the cores are inserted and

the mold halves are clamped together.

3. Pouring - The molten metal is poured at a slow rate from a ladle into the mold through

a sprue at the top of the mold. The metal flows through a runner system and enters the

mold cavity.

4. Cooling - The molten metal is allowed to cool and solidify in the mold.

5. Mold opening - After the metal has solidified, the two mold halves are opened and the

casting is removed.

6. Trimming - During cooling, the metal in the runner system and sprue solidify attached

to the casting. This excess material is now cut away (Custompart, 2010).

Table 8.7.1: Characteristics Permanent mold casting (Custompart, 2010)

Typical

Shapes

Thin-walled: Complex

Solid: Cylindrical

Solid: Cubic

Solid: Complex

Part size Weight: 0.05 kg - 300 kg

Materials

Aluminum

Copper

Magnesium

Surface finish-Ra 125 - 250 μin

Tolerance ±0.015 in

Quantity 1000-100000

Advantages

Can form complex shapes

Good mechanical properties

Many material options

Low porosity

Low labor cost

Scrap can be recycled

Disadvantages High tooling cost

Long lead time possible

75

Table 8.2: Average weekly wage in Australia (Migrationexpert, 2010)

State Average weekly earnings (AUD)

Australian Capital Territory 1,130.50

New South Wales 916.10

Northern Territory 956.60

South Australia 856.30

Tasmania 790.00

Victoria 900.30

Western Australia 1045.50

Queensland 889.90

76

Table of Contents

1 Introduction ................................................................................................................. 1

2 Objectives ................................................................................................................... 2

3 Original drill press design (MK 1) .............................................................................. 3

3.1 Essential basic functions analysis of the original design ..................................... 7

3.2 Problems with original design .............................................................................. 8

3.3 Manufacturing process of Product ....................................................................... 9

3.4 Justifications and limitations of data used............................................................ 9

3.5 Machining process of each parts of the original design (Mark 1) ...................... 11

3.5.1 Analysis of assembly time of the original design ....................................... 15

4 New drill press design (MK 2) .................................................................................. 19

4.1 Machining process of each parts of the new design (Mark 2) ........................... 23

4.1.1 Analysis of assembly time of the new design ............................................. 27

5 Discussion ................................................................................................................. 30

5.1 Comparison and analysis between old design (Mark 1) and new design (Mark 2)

30

5.1.1 Discussion and explanation on new Handle design .................................... 30

5.1.2 Discussion and explanation on new C-shaped design ................................ 31

5.1.3 Discussion and explanation on new T-shaped clamp design ...................... 35

5.2 Facts comparison between new drill press (Mark 2) and old drill press (Mark 1)

36

5.3 Functions comparison between new drill press (Mark 2) and old drill press

(Mark 1) ........................................................................................................................ 37

5.4 Functionality of the new Spring part .................................................................. 39

5.5 Design Methodology .......................................................................................... 40

5.6 Concurrent Engineering ..................................................................................... 40

5.7 Design for manufacturing (DFM) ...................................................................... 40

5.7.1 Design for assembly (DFA) ........................................................................ 41

5.8 Environmental conscious manufacturing (ECM) ............................................... 42

5.8.1 Design for environment (DFE) ................................................................... 42

5.9 Material requirement planning (MRP) ............................................................... 42

5.9.1 Lean production .......................................................................................... 43

6 Conclusion ................................................................................................................ 44

7 Reference list ............................................................................................................ 45

77

8 Appendix ................................................................................................................... 45

8.1 Tables ................................................................................................................. 46

8.2 Machining cost of each part of the original design ............................................ 46

8.3 Assembly process of the original design ............................................................ 54

8.4 Machining cost of each part of the new design .................................................. 63

8.5 Assembly process of the new design.................................................................. 66

8.6 Calculation of spring rate ................................................................................... 72

....................................................................................................................................... 72

8.7 Permanent mold casting ..................................................................................... 73

78

List of Figures

Table 3.1a: Different projections on original design .......................................................... 3

Figure 3.1: Isometric view of the original drill press.......................................................... 4

Figure 3.2: Cage of roller connecting with handle ............................................................. 5

Figure 3.3: Base of the drill press ....................................................................................... 5

Figure 3.4: Clamping position of the hand drill .................................................................. 5

Figure 4.1b: Isometric view of the new drill press ........................................................... 20

Figure 4.2: ABS clip opened ............................................................................................. 21

Figure 4.3: C-shaped connected with handle .................................................................... 21

Figure 4.4: Base of the drill press ..................................................................................... 21

Figure 5.1.1.1a: Old Handle design .................................................................................. 31

Figure 5.1.1.1b: New Handle design ................................................................................ 31

Figure 5.1.2.1a: Old C-shaped design ............................................................................... 34

Figure 5.1.2.1b: New C-shaped design ............................................................................. 34

Figure 5.1.3.1a: Old rectangular clamp design ................................................................. 36

Figure 5.1.3.2b: New T-shaped design ............................................................................. 36

Figure 5.3a: Old drill press design .................................................................................... 38

Figure 5.3b: New drill press design .................................................................................. 38

Figure 5.3.1a: Default length position of the spring ......................................................... 39

Figure 5.3.1b: Compressed length position of the spring ................................................. 39

Figure 8.1.1: Manual handling code for assembly process (Tim, 2010) .......................... 46

Figure 8.1.2: Insertion code for assembly process (Tim, 2010) ....................................... 46

Figure 8.6.1: Schematic diagram for spring mass system ................................................ 72

Figure 8.7.1: Schematic diagram of permanent mold casting (Custompart, 2010) .......... 73

79

List of Table

Table 3.1: Bill of material of original design ...................................................................... 6

Table 3.5.1: Total number and cost of machining process required in the original design

........................................................................................................................................... 11

Table 3.5.2a: Schematic diagram of stock material required for original design ............. 11

Table 3.5.2b: Total cost and amount of stock material needed for unit product .............. 12

Table 3.5.3: Manufacturing cost and time for Part 1 ........................................................ 13

Table 3.5.15: Specifications of fasteners used in the original design (Boltsnutscrewonline,

2009) ................................................................................................................................. 14

Table 3.5.1.1: Assembly cost and time of original design ................................................ 15

Table 3.4: Summary of manufacturing process of original design ................................... 18

Table 4.1a: Different projections on new design .............................................................. 19

Table 4.1: Bill of material of new design ......................................................................... 22

Table 4.1.1: Total number and cost of machining process required in the new design .... 23

Table 4.1.2: Schematic diagram of stock material required for new design..................... 23

Table 4.1.3: Required cost and amount of stock material needed for unit product for new

design ................................................................................................................................ 24


Table 4.1.11: Specifications of fasteners used in the new design (Boltsnutscrewonline,

2009) ................................................................................................................................. 26

Table 4.1.12: Specifications of the spring used in new design (Ashfield spring, 2010) .. 26

Table 4.1.1.1: Assembly cost and time of the new design ................................................ 27

Table 4.2: Summary of manufacturing process of new design ......................................... 29

Table 5.1.1.1: Comparison of specifications between old and new handle design .......... 30

Table 5.1.2.1: Comparison of specifications between old and new C-shaped design ...... 33

Table 5.1.3.1: Comparison of specifications between old and new clamp design ........... 35



Table 3.5.6a: Manufacturing cost and time for Part 4 ...................................................... 47

Table 3.5.6b: Manufacturing cost and time for Part 5 ...................................................... 48

80

Table 3.5.6c: Manufacturing cost and time for Part 6 ...................................................... 48

Table 3.5.6d: Manufacturing cost and time for Part 10 .................................................... 49

Table 3.5.6: Total manufacturing cost and time for sub-assembly of C-shaped parts ...... 49




Table 3.5.10: Manufacturing cost and time for Part 11 .................................................... 51


Table 3.5.12: Manufacturing cost and time for Part22 ..................................................... 52








Table 4.1.10: Manufacturing cost and time for Part 9 ...................................................... 65

Table 8.7.1: Characteristics Permanent mold casting (Custompart, 2010) ....................... 74

Table 8.2: Average weekly wage in Australia (Migrationexpert, 2010) .......................... 75

Documents

Mini Project for Design of Manufacturing