Manufacturing of a GT compressor blade on a 5-axis milling machine

A PROJECT REPORT ON

MANUFACTURING OF A GT COMPRESSOR BLADE USING

5-AXIS MILLING METHOD AND COMPARISION OF THE

RESULTS WITH 3-AXIS MILLING METHOD

A report submitted for partial fulfillment of the B.Tech Degree in

Mechanical Engineering

Submitted by

G.Keerthana (10011P0305)

M.Vivekanand (10011P0311)

Rabbani Kausar (10011P0314)

Azaldeen Eltaher Mohamed (10011P0319)

Under the esteemed guidance of

Dr. M. Sreenivasa Rao

Professor

DEPARTMENT OF MECHANICAL ENGINEERING

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY

KUKATPALLY, HYDERABAD – 500 085 (A.P.)

APRIL-2014



COLLEGE OF ENGINEERING, HYDERABAD-500085



COLLEGE OF ENGINEERING, HYDERABAD-500085

CERTIFICATE

This is to certify that the project report entitled “MANUFACTURING OF A GT

COMPRESSOR BLADE USING 5-AXIS MILLING METHOD AND

COMPARISION OF THE RESULTS WITH 3-AXIS MILLING METHOD”, has been

submitted by G.Keerthana (10011P0305), M.Vivekanand (10011P0311), Rabbani Kausar

(10011P0314), Azaldeen Eltaher Mohamed (10011P0319) in partial fulfillment of the

requirements for the award of degree of “BACHELOR OF TECHNOLOGY IN

MECHANICAL ENGINEERING” to the JNTUH COLLEGE OF ENGINEERING

HYDERABAD. This is a record of bonafide work carried out by them. The results of

investigations enclosed in this report have been verified and found to be satisfactory.

The results embodied in this report have not been submitted to any other university for

the award of any Degree or Diploma.

PROJECT GUIDE: HEAD OF THE DEPARTMENT:

Dr.M. Sreenivasa Rao Dr.B. Sudheer Prem Kumar

Professor (M.Tech., Ph.D. F.I.E (I))

Dept. of Mechanical Engineering Professor and Head

JNTUH College of Engineering Dept. of Mechanical Engineering

Hyderabad. JNTUH College of Engineering

Hyderabad.

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ACKNOWLEDGEMENT

This is an acknowledgement of the intensive drive and technical competence of many

individuals who have contributed to the success of our project.

I am immensely thankful to Mr. G. Madhavulu, Additional General Manager, TDL,

BHEL R&D, HYD for providing me the opportunity to carry out this project in such a reputed

organization.

I am very grateful to Mr. S. Srinu, Sr. Engineer, TDL, BHEL R&D, HYD for his

sagacious guidance and valuable suggestions during the course of our project.

My sincere thanks to Dr. B. Sudheer Prem Kumar, Head of Mechanical Engineering

Department, JNTUHCEH, Hyderabad, for granting us permission to carry out this project in

BHEL R&D, Hyderabad.

I would like to thank my internal guide Dr. M. Sreenivasa Rao, Professor, JNTUHCEH,

Hyderabad, for his encouragement and cooperation and all other staff members for the support

and motivation provided.

I like to extend my thanks to Mr. S. Biswas, General Manager, TDL, and members of

HRD for granting me permission for practical training through development of this project in

BHEL R&D, Hyderabad.

I like to express my gratitude to all members of TDL Dept. who were friendly and co-

operative

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CONTENTS

CHAPTER 1 INTRODUCTION 1

1.1 Introduction 1

1.2 Scope of present work 2

CHAPTER 2 LITERATURE REVIEW 3

2.1 Turbine and Compressor Blades 3

2.2 Gas turbine blade design 3

2.2.1 Blade Design Process 4

2.2.2 Parametric Blade Design System 5

2.2.3 Parametric Blade Representation 5

CHAPTER 3 MODELLING AND 5-AXIS TOOL PATH 7

GENERATION OF GT COMPRESSOR BLADE

3.1 Introduction to NX 7.5 7

3.1.1 NX CAD 7

3.1.2 NX CAM 8

3.2 Modelling of GT Compressor Blade 8

3.3 Drawings of GT compressor Blade 11

3.4 Blade Modelling 12

3.4.1 Part Navigator 15

3.5 Generation of 5- Axis Tool Paths 16

3.5.1 Creation of Blank 16

3.5.2 Setting Manufacturing Environment 18

3.5.3 Creating a New Operation 19

3.5.3.1 Roughing 19

3.5.3.2 Semifinishing 24

3.5.3.3 Finishing 28

3.6 Operation Navigator 31

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3.7 Simulation Compressor of Tool paths 31

3.7.1 Verify 31

CHAPTER 4 MANUFACTURING OF GT COMPRESSOR 34

BLADE

4.1 Blade Machining 34

4.2 Sturz milling method 34

4.2.1 Advantages of sturz milling 34

4.3 Machining the blade body 37

4.3.1 Roughing the Rombus 37

4.3.2 Semi finishing the blade 39

4.3.3 Finishing the blade 40

4.4 Post Processing 41

4.4.1 Post-processing sequence 42

4.4.1.1 NC Program 44

4.4.2 Post builder 46

4.5 Chiron 5-axis machine 47

4.5.1 Specifications 47

4.5.2 Components 48

4.5.3 Steps involved in machining the blade 49

CHAPTER 5 INSPECTION OF GT COMPRESSOR BLADE 53

USING 3D CMM

5.1 CMM Overview 53

5.1.1 Specifications 54

5.2 Camio V4.4 55

5.3 Inspection Procedure 56

5.3.1 Creating a Part Pragram 56

5.4 Inspection 57

5.5.1 Reporting 58

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CHAPTER 6 RESULTS AND DISCUSSIONS 60

6.1 Roughed Part 60

6.2 Semi finished Part 61

6.3 Finished Part 62

6.4 GT Compressor Blade 63

6.5 Inspection Results 64

6.6 Comparison between CMM inspected GT blade profiles- 68

Machined with 3-axis and 5-axis methods

6.7 Conclusion 70

REFERENCES 71

REFERENCES 64

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LIST OF FIGURES

FIGURE 2.1 BLADE DESIGN PROCESS 4

FIGURE 2.2 PARAMETRIC BLADE REPRESENTATION 6

FIGURE 3.1 NX 7.5 9

FIGURE 3.2 NEW PART DIALOG 10

FIGURE 3.3 NX 7.5 USER INTERFACE 11

FIGURE 3.4 BLADE PROFILE 11

FIGURE 3.5 BLADE ROOT 12

FIGURE 3.6 BLADE COORDINATES 12

FIGURE 3.7 BLADE SECTIONS 13

FIGURE 3.8 ROOT MODEL IN NX 13

FIGURE 3.9 BLADE PROFILE GENERATION 14

FIGURE 3.10 BLADE MODEL 14

FIGURE 3.11 PART NAVIGATOR 15

FIGURE 3.12 CREATION OF BLANK 17

FIGURE 3.13 BLANK 17

FIGURE 3.14 STARTING MANUFACTURING 18

FIGURE 3.15 MANUFACTURING ENVIRONMENT 18

FIGURE 3.16 CREATE ROUGHING OPERATION 19

FIGURE 3.17 CAVITY MILLING 20

FIGURE 3.18 TOOL 20

FIGURE 3.19 NEW TOOL 21

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FIGURE 3.20 MILLING TOOL 5-PARAMETERS 21

FIGURE 3.21 PATH SETTINGS 22

FIGURE 3.22 GENERATING PROGRAM 22

FIGURE 3.23 TOOL PATH ON PRESSURE SIDE 23

FIGURE 3.24 TOOL PATH ON SUCTION SIDE 23

FIGURE 3.25 CREATE SEMI FINISHING OPERATION 24

FIGURE 3.26 FIXED CONTOUR 24

FIGURE 3.27 FLAT END MILL 25

FIGURE 3.28 TOOL PATH GENERATION 25

FIGURE 3.29 SEMI FINISHING TOOL PATH WITH BLANK 26

FIGURE 3.30 SEMI FINISHING TOOL PATH WITHOUT BLANK 26

FIGURE 3.31 SEMI FINISHING TOOL PATH ON SUCTION SIDE 27

FIGURE 3.32 SEMI FINISHING TOOL PATH ON SUCTION SIDE 27

WITHOUT BLANK

FIGURE 3.33 CREATING FINISHING OPERATION 28

FIGURE 3.34 FIXED CONTOUR 28

FIGURE 3.35 SURFACE AREA DRIVE METHOD 29

FIGURE 3.36 GENERATE FINISHING TOOL PATH 29

FIGURE 3.37 FINISHING TOOL PATH ON PRESSURE SIDE 30

FIGURE 3.39 FINISHING TOOL PATH ON SUCTION SIDE 30

FIGURE 3.39 OPERATION NAVIGATOR 31

FIGURE 3.40 VERIFY TOOL PATH 32

FIGURE 3.41 ROUGHING TOOL PATH VERIFICATION 32

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FIGURE 3.42 SEMI FINISHING TOOL PATH VERIFICATION 33

FIGURE 3.43 FINISHING TOOL PATH VERIFICATION 33

FIGURE 4.1 COMPARISION OF STURZ 35

AND BALL END MILLING

FIGURE 4.2 ROUGHING THE RHOMBUS 37

FIGURE 4.3 MILLING STRATEGY 38

FIGURE 4.4 FEED DIRECTION 38

FIGURE 4.5 CUTTING PATHS 39

FIGURE 4.6 SEMI FINISHING THE BLADE 40

FIGURE 4.7 FINISHING THE BLADE 41

FIGURE 4.8 POST PROCESS 42

FIGURE 4.9 POST PROCESSED CODES 43

FIGURE 4.9 POST PROCESSOR 43

FIGURE 4.10 POST BUILDER 46

FIGURE 4.11 CHIRON 5-AXIS MACHINING CENTRE 47

FIGURE 4.12 MEASURING MCS BY OPTICAL EDGE FINDER 49

FIGURE 4.13 MACHINING PRESSURE SIDE 49

FIGURE 4.14 MACHINING SUCTION SIDE 50

FIGURE 4.15 SEMIFINISHING ON PRESSURE SIDE 51

FIGURE 4.16 SEMI FINISHING ON SUCTION SIDE 51

FIGURE 4.17 FINISHING ON PRESSURE SIDE 52

FIGURE 4.18 FINISHING ON SUCTION SIDE 52

FIGURE 5.1 LK ASCENT 3D COORDINATE MEASURING MACHINE 54

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FIGURE 5.2 CAMIO STUDIO 55

FIGURE 5.3 OPEN INSPECION BOX 56

FIGURE 5.4 INSPECTION USING 3D CMM 57

FIGURE 5.5 SLICE SELECTION ON PROFILE 58

FIGURE 5.6 TOLERANCE SPECIFIED 59

FIGURE 5.7 DIGIGRAPH VLAUES AT 100MM DISTANCE 59

FROM OF PLANE BOTTOM

FIGURE 6.1 ROUGHED MACHINING ON PRESSURE SIDE 60

FIGURE 6.2 ROUGHED MACHINING ON SUCTION SIDE 61

FIGURE 6.3 SEMI FINISHED ON PRESSURE SIDE 61

FIGURE 6.4 SEMI FINISHED ON SUCTION SIDE 62

FIGURE 6.5 FINISHED ON PRESSURE SIDE 62

FIGURE 6.6 FINISHED BLADE 63

FIGURE 6.7 GT COMPRESSOR BLADE FRONT VIEW 63

FIGURE 6.8 GT COMPRESSOR BLADE 64

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ABSTRACT

Rapid developments in the fields of engineering and their applications in

manufacturing processes brought sea change in product designs evolving more efficient and

complex designs. Conventional Ball End machining methods are not adequate to achieve the

required productivity and quality while manufacturing these components.

The aim of this report is to establish a 5-Axis programming and machining

technology using Sturz milling method, for the gas turbine compressor blade with

dovetail root configuration through which higher productivity and quality are achieved in

comparison with the Conventional Ball End machining methods.

Based on the GT compressor blade drawings, a CAD model has been generated

and the suitable tool path and the 5-Axis CNC part programs have been generated using

Unigraphics NX CAM software suitable for 5-Axis machining of the blade on the Chiron

5-Axis machine. "Sturz milling", an innovative method of sculptured surface machining,

has become not only feasible but also cost effective for the production of these

components. This report even discusses the Sturz Milling method, control parameters, its

performance in comparison with the conventional Ball End milling.

The part programs are post-processed suitable to the Chiron 5-Axis CNC machine

and the sample GT compressor rotor blade was machined. The manufacturing cycle taken

for rotor blade has come down to 2 hrs.

The inspection of blade is carried out by using a Coordinate Measuring Machine

(CMM) and its results have been compared with the results of the Conventional Ball End

machining. We have seen a significant improvement in the quality of the machined part.

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CHAPTER 1

INTRODUCTION

1.1 Introduction

Traditionally, Turbo Machinery components, such as Compressor & Turbine

blades for steam & Gas Turbines, are machined in a series of different set-ups on CNC

Machines & copy milling machines. For CNC machining of these sculptured surfaces on

3-Axes CNC machines, Ball End Mill Cutters are inevitable for facilitating each

individually conceivable point to be machined, for desired accuracy.

While copy milling process becomes difficult to maintain, because of specific

requirements of copying masters, special fixtures and tooling for each type of component

separately, the conventional CNC machining with ball end cutters proves uneconomical

due to poor machining characteristics resulting from rubbing phenomenon. The use of

CNC Machines for turbine blade machining, thus, has been very poor so far, due to non-

availability of Multi Axes CNC machines and cost effective CNC programming

techniques for sculptured surfaces. However, with the right combination of Multi Spindle

5-Axes CNC Machining Centres, 5-Axes CNC programming capabilities and suitable

machining methods, the production cost and related lead times are significantly reduced.

Compared to 3-axis machining, 5-axis machining offers many advantages,

including the ability to manufacture complex parts with free form surface, better

material-removal rates, improved surface finish, reduced number of set-ups and thus

increased productivity .

The advantages of five-axis machining are significant, and include saving time

and money, among other things. But first, it’s important to know the design of a five-axis

machine and how it works.

There are two general application categories for five-axis machining: machining

complex 3D shapes and conventional machining of tilted surfaces. In both cases, the

difficulties related to creating five-axis programs have been simplified over the years.

Like any CNC machining center, a five-axis machine has three linear axes. The

layout for these axes will be the same as any three-axis VMC or HMC. For a vertical

viewed from the front, left/right is X, fore/aft is Y and up/down is Z.

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Unlike three-axis machining centers, five-axis machining centers have two

additional rotary axes. For a VMC, the A axis is the rotary axis with a center line parallel

to the X axis. The rotary axis parallel to the Y axis is the B axis. (This is the most

common configuration for a vertical.)

Rotary axes can take one of two basic forms. One style incorporates rotary tables.

The first rotary table is mounted to the machine table and the second is mounted to the

first. The workpiece can be tilted in two directions.

With the second style of five-axis machining center, the rotary axes are

incorporated into the machine’s headstock and spindle. The spindle and cutting tool can

be tilted in each rotary axis. This method enables the workpiece to remain stationary,

which is beneficial for machining large parts. With either style, the axis conventions

remain the same. When viewing a vertical machine from the front (while X/Y is

left/right), workpiece/cutting tool tilt clockwise/counter clockwise is the B axis. When

the machine is veiwed from right side, workpiece/cutting tool tilt clockwise/counter

clockwise is the A axis.

1.2 Scope of present work

The manufacturing practices vary with different manufacturers mainly due to

The type of machine tools available.

The capability of programming the machines.

The complications in the design of the product like sharp corners , inaccessible

locations etc .

In the present work the blade of the first stage of a gas turbine compressor of 60 MV

capacity gas turbine is taken up for detailed CAM programming to enable reduced

manufacturing cycle time. The program is then loaded on a 5-Axis Chiron CNC machine

and used for producing a test blade to check and verify the correctness of the program.

The blade is then dimensionally checked down a CMM for dimensionally validity. The

CMM results are compared with that of the results when 3-Axis machining methods are

used.

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CHAPTER 2

LITERATURE REVIEW

Prior to a discussion of the earlier literature, it is worthwhile to discuss briefly the

background information

2.1 TURBINE AND COMPRESSOR BLADES

The gas turbine is an internal combustion engine that uses air as the working

fluid. The engine extracts chemical energy from fuel and converts it to mechanical energy

using the gaseous energy of the working fluid (air) to drive the engine and propeller,

which, in turn, propel the airplane Gas turbine engines are, theoretically, extremely

simple. They have three parts

Compressor - Compresses the incoming air to high pressure

Combustion area - Burns the fuel and produces high-pressure, high -velocity gas

Turbine - Extracts the energy from the high-pressure, high -velocity gas flowing

from the combustion chamber

Turbine blades and compressor blades in flight and industrial turbine engines

require complicated, tight-tolerance "root form' profiles. Many types of blades also have

additional complex geometry like Z-notch forms, seals, platforms, and locking grooves.

These complex, tight-tolerance geometries are typically machined on blades by grinding.

All design properties both for the quasi-2-D profiles and the 3-D stacking line are

parameterized in a problem-adapted way to support the understanding of the aerodynamic

engineer. These parameters are then transformed into a fully CAD-compatible B-spline

representation. The geometry engine is completed with CFD-code integration, a blade

profile optimizing package, a parametric database and a correlation utility to find good

starting solutions for new design tasks based on existing proven technology.

2.2 GAS TURBINE BLADE DESIGN

The design process is fundamentally driven by physical properties of the

components, it’s weight, performance, stress behavior and life. All these properties are

estimated by various numerical simulation methods such as FEM, CFD and crack

propagation calculations. On the design side engineers are using more and more

advanced CAD system features. Originally the CAD was just a replacement of the

drawing board to get 2-D sketches out rapidly and with the chance to correct without

starting from scratch. Then the 3-D CAD systems came up where designers could create

and combine standard geometric entities such as cylinders, cubes, tetrahedral, sphere and

free-form surfaces. Then more and more emphasis was put onto processing the

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topological information of a part or assembly. People started generating watertight solid

models in CAD

In order to process iterative changes and adjustments of a given part without

changing topology parametric CAD systems were developed. The idea of introducing

parametric into CAD revolutionized the design work and a new level of efficiency in

CAD work could be reached. Now with parametric 3-D solids as a standard, the original

work of step-by-step developing the CAD part and creating sketches, drawings and views

is more and more loosing its importance in the whole development cycle. Parameters of a

topological „master model“ can be treated outside the CAD world and can be subject to

optimizing processes or application of artificial intelligence, Neuronal networks, expert

and decision support systems. After a final optimized parametric configuration has been

detected, the parameter set is passed to the CAD and replaces the generic parameters of

the master model to create the final model.

2.2.1 Blade design process

The blade geometry design process generally plays an important rule in the

development and verification of a new gas turbine. It is the inner loop of most design

iterations and hence - taking into account the high number of different blades required for

a multistage compressor or turbine - is a critical cost factor for the task.

For a compressor blade design parameters should be sufficient with a turbine

blade potentially requiring 2-4 parameters more to meet all possible design cases. A

standard way to proceed now was to use a B-spline geometry representation and translate

the B-spline parameters 1-to-1 into the language of an aerodynamic engineer.

Figure 2.1 Blade Design Process

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Now, B-splines is the dialect that most CAD systems can understand. The only

task in-between is to transfer the parameters without loss into the 3-D solid CAD world.

Some extra work is required to do that, especially when the design works on real stream-

surfaces with varying radial height along the axis. The local coordinate systems on these

stream surfaces can be extremely dangerous, since they are not angle- or distance –

preserving. Depending on how you define them. So some integration and approximation

is necessary in the general case for the data exchange between CAD and aerodynamic

design system.

2.2.2 Parametric blade design system

The parametric blade design system is an engineering software package

designed at BRR to make the complex compressor & turbine geometry design process

better

faster

more reliable

Standardized.

The introduction of the parametric blade design system will influence other related

processes, such as FEM- and CFD-analysis and CAD-design. This has the potential to

simplify and improve the whole 3-D blade design process. The system consists of several

modules:

Auto Blading

Blade Profile Optimization

parametric Blade stacking

radial Blade smoothing and interpolation

parametric CAD interface

Parametric database.

2.2.3 Parametric blade representation

The blade profile parameters are the basis of the system. The blade

representation consists of two independent patches of higher order Bézier curves plus

leading & trailing edge geometry. Special attention is to be paid to the treatment of the

leading edge region. Currently both a circular leading edge and an elliptical leading edge

definition are used. Slope continuity is always maintained at the joint points.

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Figure 2.2 Parametric blade representations

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CHAPTER 3

MODELLING AND 5-AXIS TOOL PATH

GENERATION OF GAS TURBINE COMPRESSOR

BLADE

3.1 INTRODUCTION TO NX-7.5

NX is a premier 3D computer aided design suite. It allows you to model solid

components and assemblies, to perform engineering analyses such as mechanism

simulation and stress analysis, to create tool paths for computer-based manufacturing

processes and to perform numerous other engineering design activities in a single

software environment. Software suites like NX are referred to as product lifecycle

management (PLM) tools since they are generally integrated in the product design

process from start to finish.

Design Productivity - NX redefines CAD productivity with unique High

Definition 3D (HD3D)

CAE Productivity - NX redefines CAE productivity by integrating leading

geometry tools with powerful new analysis technology.

Manufacturing Productivity - NX redefines part manufacturing with new tools

that boost productivity including the introduction of two new applications that put

you in the context of a specific programming task. NX Turbo machinery Milling,

for programming complex blisks and impellers, produces expert results in half the

time.

NX CMM Inspection Programming – NX assists you by working automatically

off the intuitively presented PMI (Product and Manufacturing Information) model

data.

3.1.1 NX CAD

NX provides the freedom and accuracy designers need to explore shapes and

what-if styling in the modeling phase. By seamlessly combining surface and solid

modeling, as well as giving the designer access to traditional CAD tools, NX provides a

completely new kind of industrial design and styling solution. At the same time, the easy-

to-use toolbox promotes creativity and fosters innovation. These flexible tools, from

drag-and-drop templates to dynamic construction, enable fast, easy creation and

evaluation of design alternatives while providing real-time visual feedback. And there’s

no worry about changes or iterations. Associatively ensures that the design intent is

preserved every time a change occurs, without getting in the way of the designer.

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NX is not like any of the traditional systems on the market. NX promotes the

philosophy that one modeling approach is not enough when it comes to complex design

tasks. For example, the designer may begin modeling by using standard parametric

design techniques that employ curve-driven geometry. Then, when creating contours and

integrating ergonomics, the designer can use free form techniques. Or the designer could

begin modeling without precise definitions, adding geometric constraints later.

Construction geometry and style details can be rapidly generated by the dynamic

mapping of 3D curves onto free form shapes. Or surfaces can be constructed using pre-

set combinations of section and guide curves, with the designer monitoring impact as it

occurs.

3.1.2 NX CAM

NX provides complete computer-aided manufacturing (CAM) software solutions

for machine tool programming, post processing and machining simulation. NX CAM’s

advanced functions in each of its modules can maximize returns on your investments in

the latest machine tool technology. Adopted across many industries, NX delivers proven

capabilities for manufacturing in the aerospace, automotive, medical device, mold and

die, and machinery industries.

NX CAM software provides a wide range of functionality, from simple NC

programming to high-speed and multi-axis machining, enabling you to address many

tasks with one system. The flexibility of NX CAM means that you can easily complete

the most demanding jobs.

3.2 MODELLING OF GT COMPRESSOR BLADE

To start NX, use the NX 7.5 shortcut under Start (or Windows button) → (All)

Programs →UGS NX 7.5. It may take a minute or so for NX to start the first time. Once

opened, you will be presented with the window shown in Figure below.

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Figure 3.1 NX 7.5

To start modeling, you must first create a part file. NX part files use the extension

.prt for both components and assemblies of components. To create a new part, click the

New button to open the New dialog (Figure 2). For now, stay in the Model tab. Select

Model from the Templates list (the default) and set the Folder to a location on your S:

drive or desktop. The default location may be stored locally on the lab computer you are

using and might not be in your roaming profile (it might not be accessible on a different

computer). Once a folder has been selected, set the name of the part file. Click OK to

start modeling.

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Figure 3.2 New part dialogs

Once the new file has been created, the NX modeling interface will open (Figure

3). Like most modern PLM tools, the interface for NX contains numerous icons, lists, text

prompts and other features that can be incredibly overwhelming. For now, we will focus

on the sketching tools, part navigator, viewer and menu.

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Figure 3.3 NX 7.5 User Interface

3.3 DRAWINGS OF GT COMPRESSOR BLADES

Figure 3.4 Blade profile

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Figure 3.5 Blade Root

3.4 BLADE MODELLING

All the data coordinates (A,B,C,D,E and F) are imported in Unigraphics (CAD

package) using insert→ curve→ splines and a lofting procedure is performed to create

3D blade surfaces passing through the blade sections to obtain a smooth 3D blade as

shown in the Figure .

Figure 3.6 Blade coordinates

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Figure 3.7 Blade Sections

Figure 3.8 Root model in NX

Using through curves profile of the blade will be generated using surfaces> through

curves. And root of the blade is modeled using blade root diagram and extruded.

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Figure 3.9 Blade profile generation

Figure 3.10 Blade model

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3.4.1 Part Navigator

Click on the Part Navigator icon, the second icon from the top on the Resource bar

The Part Navigator provides a visual representation of the parent-child

relationships of features in the work part in a separate window in a tree type format. It

shows all the primitives, entities used during modeling. It allows you to perform various

editing actions on those features. For example, you can use the Part Navigator to suppress

or unsuppressed the features or change their parameters or positioning dimensions.

Removing the green tick mark will ‘Suppress’ the feature. The software will give a

warning if the parent child relationship is broken by suppressing any particular feature.

The Part Navigator is available for all NX applications and not just for modeling.

However, you can only perform feature-editing operations when you are in the Modeling

module. Editing a feature in the Part Navigator will automatically update the model.

Figure 3.11 Part navigator

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3.5 GENERATION OF 5-AXIS TOOL PATHS

NX-CAM offers a wide range of strategies to make efficient 5 axis programming

and include wide and flexible range of tool path generation strategies and post

processing tools to support the full range of 5-axis machine tools.

It supports a range of methods for defining precisely controlled tool paths on

complex surfaces, with effective collision and gouge checking.

It enables fast, accurate roughing and finishing of complex parts in turbo

machinery industry.

Curvature matching is new technology that constantly varies the tool angle

relative to the stock surface to maximize the tool contact area. This allows you to

remove more material with fewer passes for a given tool diameter.

Templates allow to customize the user interface and specify machining Setups

which can include machine tools, cutting tools, machining methods, shared

geometry, and sequences of operations.

The Operation Navigator allows to view and manage relationships between

operations, geometry, machining methods, and tools

NX CAM machine tool simulation provides 5-axis programmers with the

essential tools for proving out their machine motion. It offers full 3D motion of

the machine tool within its limits, driven by the post processed G-code.

3.5.1 Creation of a Blank

After completing the modeling, you should decide upon the raw material shape

and size that needs to be loaded on the machine for the actual machining. This data has to

be input in NX-7.5. This can be achieved in two ways. The first method is by creating or

importing the model of the raw material as a separate solid in the same file and assigning

that solid as the Blank. The second method is by letting the software decide the extreme

dimensions of the designed part and some offset values if wanted. The later method

allows a quick way of assigning the raw size details but it can only be used for prismatic

shapes.

Open the file ‘blade-model’

Click on START → MODELING

Create a block covering the blade as shown below

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Figure 3.12 Creation of blank

Figure 3.13 Blank

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3.5.2 Setting Machining Environment

Now we are set to get into the Manufacturing module.

Select START → MANUFACTURING

A window will pop up asking for the Machining Environment Setup. There are

many different customized CAM sessions available for different machining operations.

Here, we are only interested in the Milling operation.

Figure 3.14 Starting Manufacturing

For CAM Session Configuration, select cam_general and for CAM Setup, select

mill_contour. This window pops up when you start the Manufacturing Application

Click INITIALIZE.

Figure 3.15 Manufacturing Environment

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3.5.3 Creating a new operation

The Manufacturing setup is now ready for us to work further with Programming

Strategies. There are many different strategies involved in programming and it takes

practice to know which one is the most efficient. Here, the basic guidelines are given for

the most widely and frequently used strategies. The chapter will also cover important

parameters that are to be set for the programs to function properly.

3.5.3.1 Roughing

First Roughing will be on pressure side

Click on the Create Operation icon in the toolbar as shown

The Create Operation window will pop up.

Make sure the Type of Operation is mill_contour.

Click on the CAVITY_MILL icon at the top left as shown in the figure.

Figure 3.16 Create roughing operation

The program parameters window with CAVITY_MILL in the title bar will pop

up. On this window, you can set all the parameters for the program. A brief introduction

on every important parameter and terminology will be given as we go through the

sequence.

20 | P a g e

Figure 3.17 Cavity mill

In the CAVITY_MILL pop-up menu click on the

Specify part (blade) and specify blank.

Create New button in the TOOL, dialog box as shown below

Figure 3.18 Tool

On the New Tool window, select the Mill icon

Type in BULL_MILL as the Name and click OK

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Figure 3.19 New tool

Change diameter to 20 and Lower radius to 6.

Specify vector for tool axis

Click Ok

Figure 3.20 Milling Tool-5 Parameters

22 | P a g e

There are different options in which the tool can move. The following is a description of

each.

Figure 3.21 Path settings

Now we are done entering all the parameters required for the roughing program. It is time

to generate the program.

Click on the Generate icon at the bottom of the window.

Figure 3.22 Generating program

You can now observe the software slicing the model into depths of cuts and creating tool-

path at every level. You can find on the model cyan, blue, red and yellow lines as shown

in the figure.

23 | P a g e

Figure 3.23 Tool path on pressure side

For roughing on suction side repeat the same procedure just change the vector axis

Figure 3.24 Tool path on suction side

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3.5.3.2 Semi-Finishing



Make sure the Type of Operation is mill contour.

Click on the FIXED CONTOUR icon as shown in the figure.

Figure 3.25 Create semi-finishing operation

specify part (blade).

Change drive method to area milling and cut pattern zig with contour

Figure 3.26 Fixed contour

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Create New button in the TOOL, dialog box


Type in FLAT_END_MILL as the Name and click OK

Figure 3.27 Flat end mill

Change diameter to 12.

Specify vector for tool axis

Click Ok

In path settings method to Mill_ Semi_finishing..

click generate icon as shown below.

Figure 3.28 tool path generation

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Figure 3.29 Semi-finishing tool path with blank

Hide blank to view full tool path with blade as shown above.

Figure 3.30 Semi finishing tool path without blank

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Figure 3.31 Semi finishing tool path on suction side

Figure 3.32 Semi finishing tool path on suction side without blank

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3.5.3.3 Finishing



Make sure the Type of Operation is mill contour.

Click on the FIXED CONTOUR icon as shown in the figure.

Figure 3.33 Creating finishing operation

specify part (blade).

Change drive method to Surface area

Figure 3.34 Fixed contour

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Specify drive geometry and other parameters as shown in figure below.

Figure 3.35 Surface area drive method

Create New button in the TOOL, dialog box


Type in BALL_MILL as the Name and click OK.

select tool diameter to 12 and specify vector for tool axis.

In path settings method to Mill_ finish.

click generate icon as shown below.

Figure 3.36 Generate finishing tool path

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Figure 3.37 Finishing tool path on pressure side

Figure 3.38 Finishing tool path on suction side

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3.6 OPERATION NAVIGATOR

As soon as you get into the Manufacturing environment, you will notice many

changes in the main screen such as new icons that are displayed.

Click on the OPERATION NAVIGATOR tab on the right on the RESOURCE BAR.

The Operation Navigator gives information about the programs created and

corresponding information about the cutters, methods, and strategies.

Figure 3.39 Operation navigator

3.7 SIMULATION COMPRESSOR OF TOOL PATHS

It is very important to check the programs you have created. This prevents any

improper and dangerous motions from being made in the cutting path. It is possible that

wrong parameters and settings will be given that cause costly damages to the work piece.

To avoid such mistakes, NX7.5 and other CAM software provide Tool-path verification

and a simulation.

3.7.1 Verify:

The Tool-Path verification can be used to view the cutter motion in the entire

program. You can observe how the tool is engaged and how it retracts after cutting. It

also shows the actual material being removed through graphical simulation. You can also

view the specific zone of interest by moving the line of the program.

Right-click on the program in the Operation Navigator and choose TOOL

PATH →VERIFY or click on the Verify Tool Path button in the toolbar

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Figure 3.40 Verify tool path

This will allow you to set the parameters for visualization of the Tool-Path.

On the Tool Path Visualization window, click on the Play

icon to view the Tool Path motion.

Figure 3.41 Roughing tool path verification

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Figure 3.42 Semi-finishing tool path verification

Figure 3.43 Finishing tool path verification

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CHAPTER 4

MANUFACTURING OF GT COMPRESSOR BLADE

4.1 BLADE MACHINING

Blades of many different sizes and geometries are utilized in gas turbines, and can

perform different functions within the turbine. Some are stationary blades, while others

are rotating, and it is usually the rotating blades which present the greater machining

challenges due to their tougher materials and more complex designs. The stationary

blades, also called vanes, have simpler designs and are primarily used to direct the

airflow. Hence they are usually regarded as being easier to machine than rotating blades,

although the quality of their manufacture is still critical for turbine efficiency.

4.2 STURZ MILLING METHOD:

The key to the cost effectiveness of 5-axis CNC Machining for turbine blades, is

“Sturz” milling. “Sturz” is a German term, which refers to a milling path, where the flat end

mill cutter is inclined in the forward direction of motion. Under this method the contact

point of tool & job surface lies at the periphery unlike at the dead centre in case of

conventional ball end machining. This ensures better metal cutting performance because of

the larger effective radius and constant cutting speeds.

Though, "Sturz" milling technique, is not very new to manufacturing field, it's

application in CNC machining of turbine blades opens a new chapter in turbo machinery

manufacturing industry.

4.2.1 ADVANTAGES OF "STURZ" MILLING

The use of "Sturz" milling offers a set of distinct advantages solving many problems

faced in the traditional Ball End Milling and Disk Cutter Copy Machining of Turbine

blades.

Small scallop heights with large Cross feed: The furrow produced by “Sturz" milling

path has a wide shallow elliptical cross-sectional form instead if a semi-circle in the case

of Ball end Milling. At any given cross feed, these paths overlap and produce scallop

heights much smaller than those of disk-form cutters or ball end mill cutters of suitable

sizes. This means for a given scallop height, a blade can be machined in less number of

passes, which results in reduced machining time.

35 | P a g e

Improved Tool Life and better Surface Finish: In the Ball end Milling method, The

cutting speed at the cutter centre (dead centre) is zero while, it is maximum at the

periphery. This leads to a dominant rubbing action resulting lesser tool life and poor

surface finish. The constant cutting speed at the periphery of the tool, in case of Sturz

milling, improves the tool life and surface finish dramatically.

The use of standard Flat End milling cutters: In contrast to ball end cutters, which are

special formed cutters, the use of off-the-shelf standard flat end mill cutters as in case of

Sturz milling is highly economical. In case of flat end mill cutters the re-grinding costs

and the use of carbide inserts further improves the economic gains.

Reduced vibration and deflection problems: Unlike ball end milling, Sturz milling

results in reduced vibration and deflection because of the fact that the forces induced are

less in magnitude and not directed towards the job surface. This allows larger feed rates

and metals removal rates yielding higher productivity.

Figure 4.1 Comparison of sturz and ball end milling

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Figure 4.1 Comparison of sturz and ball end milling

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4.3 MACHINING THE BLADE BODY

Machining the blade rhombus is a critical step in blade manufacture, and a wide

variety of potential machining solutions are available depending on the design of the

blade and the types of cutting machinery available. The basic principles can be outlined,

emphasizing the machining principles which underlie them: optimizing the cutting tool

engagement, reducing vibrations, using the tooling as effectively as possible and

maximizing productivity.

4.3.1 Roughing the rhombus – parallel to the blade axis, using

one tool

This is a very common machining approach, using two separate cutting steps to

reach the full depth of cut. In most cases this method allows the cutting force to be

reduced more effectively than by reducing the feed per tooth, as it allows the chip

thickness to be modified towards the recommended target values.

Figure 4.2 Roughing the rhombus

To achieve the full benefits of this approach, the milling strategy must use down milling,

and a 45° angle of cutting entry into the workpiece.

The tool path must not change through 90° angles. Instead, change the feed direction

incrementally through small changes of radii.

Ensure a tool engagement of 60–80%, if necessary by changing the tool diameter or

cutting path..

Maximise the larger depth of cut as much as possible.

38 | P a g e

Figure 4.3 Milling strategy

Vibrations and heavy axial pressure on the inserts will occur if the feed forces

cause any movement or deflection of the workpiece.

Figure 4.4 Feed direction

Vibrations can also be reduced by adopting cutting paths which machine the metal

in small triangular steps, in both the longitudinal and lateral directions. This approach

requires modifications to the cutting speed and feed, along with no more than 60% of the

usual maximum depth of cut, and the modified cutting forces will also produce changes

in the wear patterns seen on the cutting inserts.

39 | P a g e

Figure 4.5 Cutting paths

4.3.2 Semi-finishing the blade

The semi finishing operation requires a 5-axis milling operation, and will directly

influence the surface quality of the final finished blade. Therefore the aim should always

be to achieve a very regular, uniform level of residual material if necessary, through two

separate semi finishing operations. Normally this operation is done by turn milling.

The recommended tool is an end mill with indexable inserts, such as the CoroMill

390, or a round insert milling cutter such as CoroMill 300. The choice of tool will depend

on the profile of the blade and its size.

A variety of tool paths can be employed. One common technique, especially when

machining large cast blades, is to use a feed direction along the blade length, but other

possibilities are shown in the diagram. For example, the blade can be shaped by milling

across the blade, either using several passes in one direction with a rapid return

movement between passes, or in a single continuous helical cut around the blade.

40 | P a g e

Figure 4.6 Semi finishing the blade

4.3.3 Finishing the blade

Finishing the blade is probably the most difficult 5-axis machining operation, but

its success will greatly depend on the quality of the other machining steps carried out

previously.

The most suitable tool depends on the type and size of the blade, and also on the

spindle speed and the feed available in the machining centre. The capabilities of the

machines employed can often be the limiting

factors.

In general, it is possible to use solid carbide endmills like CoroMill Plura 216.24,

or endmills with indexable inserts, such as the CoroMill 390 with inserts R390 11T3

31EPM 1025).

The tool diameters vary, e.g. between 10–20 mm.

The principal problems when finishing are vibrations, and the quality of the pre-

finished surfaces. Using tools with a smaller radius, r, or using a different number of

inserts in the cutting head can help combat vibrations, in line with the recommendations

given in Coromant publications During the cutting process the tool follows a helical path

around the blade, a path controlled by a specialised CAD-CAM system.To achieve the

41 | P a g e

best surface quality and structure, the tool has to maintain a constant normangle at each

point on the surface, and always in a downmilling manner.

Figure 4.7 Finishing the blade

4.4 POST PROCESSING

The primary use of the Manufacturing application is to generate tool paths in

order to manufacture parts. Generally, we cannot just send an unmodified tool path file to

a machine and start cutting because there are many different types of machines. Each

type of machine has unique hardware capabilities, requirements and control systems. For

instance, it can have a vertical or a horizontal spindle; it can cut while moving several

axes simultaneously, etc. The controller accepts a tool path file and directs tool motion

and other machine activity (such as turning the coolant or air on and off).

Naturally, just as each type of machine has unique hardware characteristics;

controllers also differ in software characteristics. For instance, most controllers require

that the instruction for turning the coolant on be given in a particular code. Some

controllers also restrict the number of M codes that are allowed in one line of output. This

information is not in the initial NX7.5 NX tool path.

`Therefore, the tool path must be modified to suit the unique parameters of each

different machine/controller combination. The modification is called post processing. The

result is a post processed tool path.

Tool paths consist of GOTO points and other information that controls the

movement of a tool with respect to the part. This unmodified tool path usually needs to

be specifically formatted for a particular machine tool/controller combination.

Differences are based on character formats, tool change requirements, type of machine,

number of controlled axis of motion, etc.

The tool path must be formatted to match the unique characteristics of the

machine tool/controller combination. The procedure of modifying this generic tool path

42 | P a g e

to a form that can be understood and used by the machine tool controller is called post

processing.

Two elements are required for post processing. They are:

• Tool path - A NX internal tool path

• Post processor - this is a program that reads, converts and reformats tool path

information for a particular machine tool/controller combination.

4.4.1 Post-Processing sequence

Click on a program in the Operation Navigator that you want to post process.

Click TOOLS → OPERATION NAVIGATOR → OUTPUT → NX

POSTPROCESSING

Select the MILL_5_AXIS machine and enter a location for the file

Select OK

This will create the post-processed file for the desired machine. It can be seen that the

block numbers with G and M codes concerning the Machine controller type.

Figure 4.8 post process

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Figure 4.9 Post processed codes

5-axis machining requires machine-control (NC) post processing to convert the

cutter-location (CL) data that define the tool path data with a CAM system into the NC

data that the machine can read.

NC Post processing is the process of translating machining instructions from a

CAM system into NC program code for a unique machine.

The tool path data is reformatted by the postprocessor for the machine.

Figure 4.10 postprocessor

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4.4.1.1 NC PROGRAM

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Date : 7/4/2014 3:41:35 PM

Current work part : C:\Documents and Settings\cimar07\Desktop\mech

project\fr6-rot02.prt

Node name : cimar07

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%

N0010 G40 G17 G94 G90 G70

N0020 G91 G28 Z0.0

:0030 T00 M06

N0040 G0 G90 X3.4646 Y-2.9724 A270. B0.0 S0 M03

N0050 G43 Z1.8765 H00

N0060 Z1.3915

N0070 G1 Z1.2734 F9.8 M08

N0080 X2.874

N0090 Y-7.5

N0100 G2 X2.6772 Y-7.6969 I-.1969 J0.0

N0110 G1 X-2.6772

N0120 G2 X-2.874 Y-7.5 I0.0 J.1969

N0130 G1 Y1.5551

N0140 G2 X-2.6772 Y1.752 I.1969 J0.0

N0150 G1 X2.6772

N0160 G2 X2.874 Y1.5551 I0.0 J-.1969

45 | P a g e

N0170 G1 Y-2.9724

N0180 X2.6772

N0190 Y-7.5

N0200 X-2.6772

N0210 Y1.5551

N0220 X2.6772

N0230 Y-2.9724

N0240 X2.4803

N0250 Y-7.3031

N0260 X-2.4803

N0270 Y1.3583

N0280 X2.4803

N0290 Y-2.9724

N0300 X2.2835

N0310 Y-7.1063

N0320 X-2.2835

N0330 Y1.1614

N0340 X2.2835

N0350 Y-2.9724

N0360 X2.0866

N0370 Y-6.9094

N0380 X-2.0866

N0390 Y.9646

N0400 X2.0866

N0410 Y-2.9724

46 | P a g e

4.4.2 Post builder

Type of machine controller and different parameters suited for machine are

specified in post builder

Figure 4.11 Post builder

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4.5 CHIRON 5-AXIS MACHINE

Figure 4.12 chiron 5-axis machining centre

4.5.1 SPECIFICATIONS

MANUFACTURER: Chiron, Germany

Controller : Sinumeric 840D

Travel:

X-axis 800 mm

Y-axis 630 mm

Z-axis 550 mm

Spindle AC-motor17,0 kW at 100 % 47,2 kW at 5 % for mainspindle

Spindle speed range: 20 - 12.000 rpm - max.180 Nm

COLUMN MOVING MACHINING CENTRE with swing setup Linear-guide ways

with long-term grease lubrication

Digital direct drives AC-servo motors for x-, y- and z-axes with

direct absolute path Glass scales measuring system over pressured in all axes rapid

traverse in all axes 60 m/min. acceleration 0.5 m/s2

210 bar Hydraulic unit incl. valves for supply and clamping circuit for clamping of

faceplate and counter bearing complete with hydraulic connection

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Scratch Band Chip conveyor and PF 50 / KFA 900 Coolant Equipment: tank

capacity 900 l, pump capacity from 100 l/min at 2,1 bar up to 250 l/min at 1,8 bar high

pressure pump capacity 20 l/min at 30 bar high pressure circuit with filtration via paper

bond filter, filtration

50 Rm nominal. Twin filter in the high pressure circuit for the protection of the machine.

No of tools : 24

No of axes: 5 axes continuous.

Max job weight: 300Kg.

4.5.2 COMPONENTS

NC swivel head

The NC swivel head with hydraulic clamping and water-cooled motor spindle has a

swivelling range of ± 110° and distinguishes itself by its exceptionally high rigidity,

overload capacity and speed.

CNC CONTROL

The MILL series can be delivered with a Siemens, Fanuc or Heidenhain CNC

control. A CNC machine controller runs G-code and M code programs and provides the

user interface between the machine and the operator. The controller is capable of full 5-

axes simultaneous motion.

AUTOMATIC TOOL CHANGE USING THE PICK-UP METHOD,

Starting from 1.5 s (24 / 40 / 60 tool places) The tool changing system is a quick,

failure-proof pick-up system. It takes only 1.5 s to change tools. The chain magazine with

24 (optionally 40) tool places is designed for tool holders with ISO 40 or HSK-A 63 and

separated from the working area. Tools with a diameter of up to 125 mm and length of up

to 280 mm can be used.

TOOL MAGAZINE

Tools are made available from the background magazine (92 or 165 ISO / CAT

40 or HSK-A 63 tool places) during machining. The intelligent tool management chain

serves as storage for frequently used tools. If more tools are required, a background

magazine can also be used during the machining operation. A total of 92 tools can be

used. These tools are assigned to specific magazine places with fixed codes and

are immediately brought back to their respective places after use.

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4.5.3 STEPS INVOLVED IN MACHINING THE BLADE

Blank Selection and Measuring MCS by Optical Edge Finder

Figure 4.13 Measuring MCS by optical edge finder

Machining of Pressure Side using bull nose cutter of diameter 20mm and lower radius 6

mm

Figure 4.14 Machining pressure side

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Machining of Suction Side using bull nose cutter of diameter 20mm and lower radius 6

mm

Figure 4.15 Machining suction side

Semi finishing operation done by flat end mill cutter of diameter 12mm on pressure side

51 | P a g e

Figure 4.16 Semi finishing on pressure side

Semi finish operation done by flat end mill cutter of diameter 12mm on suction side

Figure 4.17 Semi finish on suction side

The finishing of blade on pressure and also chamfer of the root is done by ball nose cutter

of 12mm dia.

52 | P a g e

Figure 4.18 Finishing on pressure side

Figure 4.19 Finishing on suction side

53 | P a g e

CHAPTER 5

INSPECTION OF GT COMPRESSOR BLADE USING

3D-CMM

5.1 CMM OVERVIEW

LK CMMs are available in various configurations based on overhead beam or

horizontal spindle designs. The CMM axes move on a cushion of air supplied by air

bearings and are assembled around a granite work surface. The granite work surface has a

number of drilled and tapped holes to allow for part location. The axes of the CMM allow

measurements to be made on a part or work piece in a Cartesian co-ordinate system.

Points are taken with a probe mounted on the Z axis spindle. The axes can be moved

manually with the joysticks on the hand box, or through CNC to facilitate probing and the

taking of points. Point data is supplied to a computer via the reading of digital encoders

on optical scales. There is one optical scale for each axis of the CMM. During correct

operation the CMM ‘knows’ the precise location of the probe as points are taken. The

axes are driven by motors acting either via belts or on drive bars. The CMM is connected

through an electronic control unit to a computer workstation. Output devices for the

computer comprise a VDU and printer and provision is also made for connection to a

network.

54 | P a g e

Figure 5.1 LK Ascent – 3D Coordinate Measuring Machine

5.1.1 Specifications

Name: 3D CNC CMM

Manufacturer: LK (Metris), UK

Model: Ascent

Type: Bridge

Range: 8.7.6

Controller: ACT

Application Software: Camio 4.4

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5.2 Camio v 4.4

Metris Camio is the combined inspection and programming environment for CMMs. It is

available as a suite of metrology software solutions. Camio can allow you to create

inspection programs off-line from the 3D CAD model design, or by manually

programming on-line, or by a combination of these methods. It can provide full 3D

geometric modeling capabilities, and supports SAT®, IGES, VDA, CATIA® and other

file formats. Programs can be executed in manual or CNC (program or automatic) mode,

and the results reported in text or graphical format against the 3D CAD model.

Camio conforms to the specifications of the Dimensional Measuring Interface

Specification (DMIS). It is assumed that users are familiar with this specification and

with the basics of inspection using CMMs.

Figure 5.2 Camio Studio

56 | P a g e

5.3 INSPECTION PROCEDURE

The manufactured test blade and the heat treated test blades are inspected for

deviations using the 3D Coordinate Measuring Machine.

5.3.1 Creating a Part Program

When you create a new program, a template of DMIS commands is inserted in

your program. If Camio cannot find the DMIS template file that contains these

commands, it will create one for you.

To create a new part program, select New Program from the File menu. If you

wish to use any default tolerances you have previously defined using the Tolerance

dialog box, check the Use default tolerances box in the New Inspection dialog box (click

the Advanced button). Otherwise, any required tolerances must be defined in the part

program.

Check input, output, DTA, XML files in Output options.

Open the iges model file in Model options.

Check the CSV option in Reporting option.

Figure 5.3 Open Inspection Box

57 | P a g e

5.4 INSPECTION

The inspection is done by selecting a slice 100mm distance from bottom of the

blade.

The slice is made into number of divisions or spacing can also be given and values

are noted at these points are then read into the computer.

The Inspect measure icons allow the user to measure features.

The tolerance values are given in the tolerance command.

Then inspect curve option is selected to measure to measure the profile of blade.

Nominal values of the blade are also given as per the drawing.

Figure 5.4 Inspection using 3DCMM

58 | P a g e

Figure 5.5 Slice selection on profile

5.4.1 Reporting

LK Studio Reporting allows to output text and graphics reports from inspection

data. A report will be created by selecting LK Studio Reporting option.

The report can be obtained either in notepad or in excel sheets. Graphical reporting

can be obtained using digigraph.

The results give the deviations in blade by considering the actual, nominal and

tolerance values.

59 | P a g e

Figure 5.6 Tolerance specified

Figure 5.7 Digigraph values at 100mm distance from of plane bottom

60 | P a g e

CHAPTER 6

RESULTS AND DISCUSSIONS

The results of machining at different stages, like Roughing, semi finishing, and

finishing are discussed below. Also discussed are the results of inspection of specimen

blade.

6.1 Roughed part

This process begins with raw stock, known as billet, and cuts it very roughly to

shape of the final model. In milling, the result often gives the appearance of terraces,

because the strategy has taken advantage of the ability to cut the model horizontally.

Common strategies are zig-zag cleaning, offset cleaning, plunge roughing, rest roughing.

Figure 6.1 Rough Machined on Pressure side

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Figure 6.2 Rough Machined on suction side

6.2 Semi-finished part

This process begins with a roughed part that unevenly approximates the model

and cuts to within a fixed offset distance from the model. The semi-finishing pass must

leave a small amount of material so the tool can cut accurately while finishing, but not so

little that the tool and material deflect instead of shearing.

Figure 6.3 Semi finished on pressure side

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Figure 6.4 Semi finished on suction side

6.3 Finished part

Finishing involves a slow pass across the material in very fine steps to produce the finished part. In finishing, the step between one pass and another is minimal. Feed rates are low and spindle speeds are raised to produce an accurate surface.

Figure 6.5 finished on pressure side

63 | P a g e

Figure 6.6 finished blade

6.4 GT compressor blade

Figure 6.7 GT compressor blade front view

64 | P a g e

Figure 6.8 GT compressor blade

6.5 INSPECTION RESULTS

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--------------------------------------------------------------------------------

Point:PNT005

X-axis -9.4002 -9.3049 -0.0300 +0.0300 -0.0953 <--+--- -0.0653

Y-axis -15.2882 -15.1554 -0.0300 +0.0300 -0.1328 <--+--- -0.1028

Z-axis -95.0013 -95.0025 -0.0300 +0.0300 0.0012 ---*---

--------------------------------------------------------------------------------

Point:PNT006

X-axis -6.7887 -6.6950 -0.0300 +0.0300 -0.0937 <--+--- -0.0637

Y-axis -17.1194 -16.9829 -0.0300 +0.0300 -0.1365 <--+--- -0.1065

Z-axis -94.9916 -94.9921 -0.0300 +0.0300 0.0005 ---*---

--------------------------------------------------------------------------------

Point:PNT014

X-axis -12.2901 -12.2038 -0.0300 +0.0300 -0.0863 <--+--- -0.0563

===============================================================

=================

66 | P a g e


--------------------------------------------------------------------------------


ERROR

--------------------------------------------------------------------------------

Y-axis 13.2435 13.1255 -0.0300 +0.0300 0.1180 ---+--> 0.0880

Z-axis -95.0111 -95.0121 -0.0300 +0.0300 0.0010 ---*---

--------------------------------------------------------------------------------

Point:PNT015

X-axis -9.5297 -9.4525 -0.0300 +0.0300 -0.0772 <--+--- -0.0472

Y-axis 15.1758 15.0521 -0.0300 +0.0300 0.1237 ---+--> 0.0937

Z-axis -95.0132 -95.0142 -0.0300 +0.0300 0.0010 ---*---

--------------------------------------------------------------------------------

Point:PNT016

X-axis -7.1900 -7.1085 -0.0300 +0.0300 -0.0815 <--+--- -0.0515

Y-axis 16.8143 16.6933 -0.0300 +0.0300 0.1210 ---+--> 0.0910

Z-axis -95.0350 -95.0361 -0.0300 +0.0300 0.0011 ---*---

--------------------------------------------------------------------------------

Point:PNT009

X-axis -4.3095 -4.2438 -0.2000 +0.2000 -0.0657 --*+---

Y-axis -17.2432 -17.3473 -0.2000 +0.2000 0.1041 ---+-*-

Z-axis -10.0029 -10.0040 -0.2000 +0.2000 0.0011 ---*---

--------------------------------------------------------------------------------

Point:PNT010

X-axis -1.5744 -1.5120 -0.2000 +0.2000 -0.0624 --*+---

Y-axis -15.6324 -15.7382 -0.2000 +0.2000 0.1058 ---+-*-

Z-axis -10.0290 -10.0293 -0.2000 +0.2000 0.0003 ---*---

--------------------------------------------------------------------------------

Point:PNT019

X-axis -1.2959 -1.2375 -0.2000 +0.2000 -0.0584 --*+---

Y-axis 15.4808 15.5765 -0.2000 +0.2000 -0.0957 --*+---

Z-axis -10.0012 -10.0031 -0.2000 +0.2000 0.0019 ---*---

--------------------------------------------------------------------------------

Point:PNT020

X-axis -4.3593 -4.3022 -0.2000 +0.2000 -0.0571 --*+---

Y-axis 17.2882 17.3818 -0.2000 +0.2000 -0.0936 --*+---

Z-axis -9.9847 -9.9857 -0.2000 +0.2000 0.0010 ---*---

--------------------------------------------------------------------------------

Point:PNT007

X-axis -4.2809 -4.2388 -0.2000 +0.2000 -0.0421 --*+---

Y-axis -17.2789 -17.3444 -0.2000 +0.2000 0.0655 ---+*--

Z-axis -95.0162 -95.0167 -0.2000 +0.2000 0.0005 ---*---

--------------------------------------------------------------------------------

Point:PNT008

X-axis -1.2622 -1.2253 -0.2000 +0.2000 -0.0369 --*+---

Y-axis -15.5018 -15.5693 -0.2000 +0.2000 0.0675 ---+*--

67 | P a g e

Z-axis -94.9986 -94.9991 -0.2000 +0.2000 0.0005 ---*---

--------------------------------------------------------------------------------

Point:PNT017

X-axis -4.1095 -4.0569 -0.2000 +0.2000 -0.0526 --*+---

Y-axis 17.1505 17.2373 -0.2000 +0.2000 -0.0868 --*+---

Z-axis -94.9903 -94.9914 -0.2000 +0.2000 0.0011 ---*---

--------------------------------------------------------------------------------

Point:PNT018

X-axis -1.1281 -1.0741 -0.2000 +0.2000 -0.0540 --*+---

Y-axis 15.3916 15.4803 -0.2000 +0.2000 -0.0887 --*+---

Z-axis -95.0094 -95.0106 -0.2000 +0.2000 0.0012 ---*---

--------------------------------------------------------------------------------

Plane:PLN001--Plane:PLN002

===============================================================

=================

--------------------------------------------------------------------------------


--------------------------------------------------------------------------------


ERROR

--------------------------------------------------------------------------------

Angle-XY 70.0201 70.0000 -0.1000 +0.1000 0.0201 ---+*--

--------------------------------------------------------------------------------


Angle-XY -61.0297 0.0000 -0.1000 +0.1000 -61.0297 <--+--- -60.9297

--------------------------------------------------------------------------------


Angle-XY 61.0297 61.0000 -0.1000 +0.1000 0.0297 ---+*--

--------------------------------------------------------------------------------

68 | P a g e

6.6 Comparison between CMM inspected Turbine

Blade Profiles- machined with 3-axis and 5-axis

methods

69 | P a g e

The comparison of the turbine blade profiles machined with 3-axis and 5-axis

methods can be carried out by overlapping the output digigraphs from the CMM of both

the methods. See the above figure.

Inner and Outer Profile (Cyan) Tolerance Limits are +/- 100μ.

When machined with 3-axis method,

The pressure and suction sides are undercut, due to the curvatures.

The trailing and the leading edges are overcut due to run away and the

vibrations in the machine.

When machined with 5-axis method,

The blade profile machined is neither undercut nor overcut as the machining is

not affected by the vibrations of the machine.

Thus the accuracy of the machined blade in 5-axis method is higher than that of the

3-axis method thus increasing the quality of the machining.

70 | P a g e

6.7 CONCLUSION

Modeling, manufacturing and inspection procedure of the GT compressor blade

has been discussed in the report. The type of milling technique used is Sturz Milling,

which may not be a new technique in manufacturing, but it's application in CNC

machining of turbine blades opens a new chapter in turbo machinery manufacturing

industry.

5-axis machining is observed to be more productive over conventional 3-axis

machining. The machining time has been reduced to 2hrs, with a higher surface finish in

single setup.

Thus 5-axis machining using Struz milling techniques for the manufacturing of GT

compressor turbine blades gives a superior quality.

71 | P a g e

REFERENCES

1. "An Integrated Turbine Blade Manufacturing System" by Randy Schmid,

Published in AUTOFACT 6, 1984.

2. Unigraphics V10.4.1 CAD/CAM software manuals.

3. C.G. Jensen, W.E. Red, J. Pi (2002), “Tool selection for five-axis curvature

matched machining ”, Computer Aided Design vol. 34, pp. 251-266

4. NX Manufacturing Fundamentals, Student Guide, April 2007, Publication Number

MT11021 — NX 5

5. Dunham, J. A parametric method of Turbine Blade Profile design, ASME Paper

74-GT-119, 1974

6. Korakianitis, T. and Pantazoupulos, G.I.: Improved Turbine-Blade Design

techniques

7. using 4th order paramertic spline segments, Computer Aided design, Vol. 25,

No.5, pp.289-299,1993.