DESIGN AND ANALYSIS OF A SMALL-SCALE COST-EFFECTIVE CNC MILLING MACHINE

ABSTRACT 

This thesis aims to explore the theories and techniques behind procedures of developing a high precision cost-effective mini CNC milling machine. This newly designed machine tool can be widely used in electrical and medical industry for making small parts and engraving small features. Various structures were explored and compared during the design stage. Different commercial products were carefully selected and purchased from  the  Chinese market. PMAC from Delta Tau was used as  the  motion controller. Different setup and configuration issues using PMAC were explored. A newly designed motion controller using Arduino and TI MSP430 was also tested and implemented as a replacement of PMAC to reduce cost. Fabricated prototype machine was calibrated and tested under various self-testing procedures to meet industrial
standard. Comprehensive cost analysis and profit estimation was conducted after
completion of the machine tool prototype.

TABLE OF CONTENTS 

Chapter 1: Introduction……………………………… 1 
1.1    Market Research  …………………………. 3
1.2    General Research Objectives  ……………………….. 5
1.3    Summary  ………………………………… 7
1.4    Figures and Tables ………………………. 8

Chapter 2: Literature Review ……………………….. 10 
2.1    CNC concepts  ……………………………. 11
2.2    Design consideration of CNC machine tools …………………… 12
2.3    Summary  ………………………………. 14
2.4    Figures and Tables  …………………….. 16

Chapter 3: Structure Design and Analysis  ……………………… 17 
3.1    Structure Comparison …………………………… 18
3.2    Structural Analysis  …………………….. 20
3.3    Summary  ………………………………. 23
3.4    Figures and Tables  …………………….. 24

Chapter 4: Machine Fabrication  ……………………. 29 
4.1    Selection of Components ………………………….. 29
4.1.1    Selection of motors  …………………………. 29
4.1.2    Selection of linear guides and lead screws  ……………. 33
4.1.3    Selection of feedback sensors  ………………. 34
4.1.4    Other essential parts and accessories ………………….. 35
4.1.5    Cost summary …………………………….. 36
4.2    Machine assembling  ……………………………… 37
4.3    Summary  ………………………………. 38
4.4    Figures and Tables  …………………….. 40

Chapter 5: Controller Design and Setup ……………………….. 47 
5.1    Hardware connection and setup  ……………………. 49
5.2    Software Configuration …………………………….. 53
5.2.1    Controller Setup  ………………………….. 53
5.2.2    Coordinate system, home, HMI setup ………………….. 56
5.3    Alternate servo controller design  …………………… 59
5.4    Summary  ………………………………. 61
5.5    Figures and Tables …………………….. 63

Chapter 6: Machine Test and Calibration  ………………………. 76 
6.1    Flatness and perpendicularity test  …………………. 77
6.2    Circular test  …………………………… 80
6.3    Summary  ………………………………. 82
6.4    Figures and Tables …………………….. 84

Chapter 7: Conclusion  ……………………………… 99 
7.1    Future studies  …………………………. 100
References  …………………………….. 102
Appendix: CAD Drawing of all machine parts  ………………….. 105 

DESIGN AND ANALYSIS OF A SMALL-SCALE COST-EFFECTIVE CNC MILLING MACHINE