iii
TABLE OF CONTENT
Abstract
i Acknowledgement
ii Table of Content
iii List of Tables
vi List of Figures
vii List Abbreviations
ix
CHAPTER 1: INTRODUCTION 1
1.1 Overview Background 1
1.2 Problem Statement 3
1.3 Objectives 4
1.4 Scope 4
1.5 Project Organization 5
CHAPTER 2: LITERATURE REVIEW 6
2.1 Types and Constructions of CMM 6
2.2 Probing System8 2.2.1 Classifications and Categories of Probing System
8 2.2.2 Touch-Trigger Probes
11 2.2.2.1 Kinematic Resistive Probe Operation
13 2.2.2.2 Strain-gauge and Piezo Probes Operation
14 2.2.2.3 Touch Trigger Probe Performance
16 2.3 Factors Influence the Probing Accuracy of CMM
19 2.3.1 Stylus Length
19 2.3.2 Stylus Tip Diameter
21 2.3.3 Probe Approach Distance
22 2.3.4 Approach Speed of the Probe
23 2.3.5 Sampling planning
24 2.4 Errors in Measurement
25 2.4.1 Sources of Errors
26
iv 2.4.2 Types of Errors
26 2.4.2.1 Systematic Error
27 2.4.2.2 Random Error
28 2.5 Uncertainties of Measurements
28 2.5.1 Sources of Uncertainty
29 2.5.2 Model of Measuring Uncertainty
30 2.5.2.1 Standard Uncertainty
30 2.5.2.1.1 Type A Evaluation
31 2.5.2.1.2 Type B Evaluation
31 2.5.2.2 Combined Standard Uncertainty
32 2.5.2.3 Expanded Uncertainty
33
CHAPTER 3: METHODOLOGY 34
3.1 Overview 34
3.2 Experiment Definition 36
3.3 Experiment Parameters and Variables 36
3.4 Design of Experiment DOE 37
3.5 Conducting the Experiment 39
3.6 Data Collection 40
3.7 Data Analysis 40
3.8 Findings and Conclusions 41
3.9 Summary 41
CHAPTER 4: RESULTS AND DISSCUSSION 42
4.1 Overview of the experiment and Data Collection 42
4.2 Results 43
4.2.1Analysis of Variance ANOVA 46
4.2.1.1 ANOVA Model for Uncertainty 46
4.2.1.2 ANOVA Model for Pre-travel Variation 49
4.2.2 Comparison of Probe Pre-travel Variation 52
4.2.2.1 Comparison of Stylus Length effect on the Pre-travel Variation 53
4.2.2.2Comparison of Tip Diameter Effect on the Pre-travel Variation 57
v 4.2.2.3 Comparison of Approach Distance Effect
on the Pre-travel Variation 62
4.3 Discussion 71
CHAPTER 5: CONCLUSION RECOMMENDATION 75
5.1 Conclusion 75
5.2 Recommendation 77
REFERENCES 78
APPENDICES 83
A Gantt Chart
B Stylus Kit Technical data C Data Collection
vi
LIST OF TABLES
2.1 Trigger Sensing Technologies 11
2. 2 Comparison of the Type A and Type B Evaluations 32
3. 1 The Independent Parameters and Variables 36
3. 2 Full factorial design 38
4. 1 Overall Results 45
4. 2 ANOVA table for uncertainty 47
4. 3 ANOVA table for pre-travel variation 50
4. 4 Experiment results of different stylus length at 2 mm tip diameter and 5 mm react
53 4. 5 Experiment results of different stylus length
at 4 mm tip diameter and 5 mm react distance 55
4. 6 Experiment results of different stylus length at 6 mm tip diameter and 5 mm react distance
55 4. 7 Experiment results of different Tip diameter
at 10 mm stylus length and 5 mm react distance 57
4. 8 Experiment results of different Tip diameter at 30 mm stylus length and 5 mm react distance
59 4. 9 Experiment results of different Tip diameter
at 50 mm stylus length and 5 mm react distance 61
4. 10 Experiment results of different Tip diameter and stylus length at 10 mm stylus length
63 4. 11 Experiment results of different Tip diameter
and stylus length at 30 mm stylus length 66
4. 12 Experiment results of different Tip diameter and stylus length at 50 mm stylus length
69
vii
LIST OF FIGURES
2.1 Bridge Type CMM CONTURA G2
7 2.2
Classification criteria for probing systems 8
2.3 Sensors for coordinate measuring machines
classified by principle of operation 9
2.4 Basic tactile probing system in kinematic resistive design
10 2.5a
one stage type with electro-switch transducer 12
2.5b two stage type with three piezo-elements
12 2.6
schematic of a kinematic resistive probe 13
2.7 The Mechanics of Kinematic Resistive Probe
14 2.8
Schematic of a Strain Gauge Probe Measuring the Contact Force 15
2.9 schematic of a Piezo Probe
15 2.10
Force Balance in a Touch-trigger 16
2.11a pivot point is further from stylus centerline in high force direction
17 2.11b pivot point is closer to stylus centerline in low force direction
17 2.11c
force balance in a touch-trigger probe 17
2.12 Force Balance in the Z Direction
18 2.13
Pre-travel Variation Plot for a Kinematic Resistive TP6 CMM probe 18 2.14
Pre-travel Variation Plot for a Strain-gauge TP7M Touch-trigger Probe
19 2.15
Errors of Touch trigger Probe of Different Stylus Length 20
2.16 Probe Performance of Different Stylus Length
20 2.17
The influence of the stylus length and the measuring force on the one-stage probe characteristic
21 2.18
Range of styli with different ruby ball sizes 21
2.19 CMM dynamic error as a function of probe approach distance
22 2. 20
Three-dimensional probe uncertainty for different 23
2.21 Example results from a Probe Test
25 2. 22
Systematic and random error 27
2.23 Steps of measurement errors enter into the measurement uncertainty 29
2. 24 Error components that lead to uncertainties
30
viii 3.1
Project Flowchart 35
4.1 Histogram of residuals of the measurement results
44 4. 2
Normality test plots of residuals 44
4.3 Interaction plot of stylus length with tip diameter for uncertainty
48 4.4
Main effect plot for uncertainty 49
4.5 Interaction plot of stylus length with tip diameter
for pre-travel variation 51
4.6 Main effect plot for pre-travel variation
52 4.7
Pre-travel variation of different stylus Length at a constant tip diameter of 2 mm and react distance of 5 mm.
54 4. 8
Pre-travel variation of different stylus Length at a constant tip diameter of 4 mm and react distance of 5 mm
56 4. 9
Pre-travel variation of different stylus Length at a constant tip diameter of 6 mm and react distance of 5 mm.
56 4.10
Pre-travel variation of different tip diameter at a constant stylus length of 10 mm and approach distance of 5 mm. 58
4. 11 Pre-travel variation of different tip diameter at a constant
stylus length of 30 mm and approach distance of 5 mm 60
4. 12 Pre-travel variation of different tip diameter at a constant
stylus length of 50 mm and approach distance of 5 mm 62
4. 13 Pre-travel variation of different approach distance
at a constant stylus length of 10 mm and tip diameter of 2 mm 64
4. 14 Pre-travel variation of different approach distance
at a constant stylus length of 10 mm and tip diameter of 4 mm 65
4. 15 Pre-travel variation of different approach distance
at a constant stylus length of 30 mm and tip diameter of 2 mm 68
4. 16 Pre-travel variation of different approach distance
at a constant stylus length of 30 mm and tip diameter of 4 mm 68
4. 17 Pre-travel variation of different approach distance
at a constant stylus length of 50 mm and tip diameter of 2 mm 70
4. 18 Pre-travel variation of different approach distance
at a constant stylus length of 50 mm and tip diameter of 4 mm 71
ix
LIST OF ABBREVIATIONS
ANOVA – Analysis of Variance
CMM -
Coordinate Measuring Machine CMS
– Coordinate Measuring System
CNC –
Computer Numerical Control DOE
- Design of Experiment
GUM -
Guide to the expression of Uncertainty Measurement ISO
- International Organization for Standardization
PTV –
Pre-travel Variation RSS
- Root Sum of the Square
TP -
Touch Probe UTeM
- Universiti Teknikal Malaysia Melaka
VIM -
International Vocabulary of basic and general terms in Metrology
1
CHAPTER 1 INTRODUCTION
