PRODUCIBILITY OF COMPOSITE POSITION TOLERANCE SPECIFICATIONS FOR PATTERNS OF HOLES AND EVALUATION OF MACHINE ACCURACY
Open Access
- Author:
- Golhar, Abhijeet Dagdu
- Graduate Program:
- Industrial Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 26, 2018
- Committee Members:
- El-Amine Lehtihet, Thesis Advisor/Co-Advisor
Edward Demeter, Thesis Advisor/Co-Advisor - Keywords:
- Composite position tolerance
Producibility of composite position tolerance variants
Machine Accuracy - Abstract:
- The practical application and implementation of the composite position tolerance control in design and manufacturing are somewhat hampered by lack of information related to the ease or difficulty of production. This work evaluates the producibility of the composite position tolerance on three different types of variants for patterns of holes. The influence of design and manufacturing variables on producibility is evaluated. The thesis also evaluates the accuracy of a set of subtractive manufacturing processes. Two CNC machining centers available in the Industrial and Manufacturing Engineering Department at the Pennsylvania State University were used for this evaluation. Three different patterns of holes namely circular, rectangular, and linear patterns were designed and produced on each of these machines. Two replicates of each pattern were produced. Three-dimensional position and size data of the holes were collected using a coordinate measuring machine (CMM); this data was then used to estimate the minimum composite position tolerance values that will satisfy a given pattern. The data thus obtained is used to differentiate between the accuracy of the two machines and assess the producibility of the composite tolerance constraints. The influence of pattern design, variant type and the number of features per pattern across different location were studied as well. It was found out that a new 2015 HAAS VF-2 CNC machining center-1 shows consistent results for positioning as compared to a 2001 HAAS VF-0 CNC machining center-2. The performance of the CNC machining center-1 for the producibility of composite position tolerance is better than the CNC machining center-2. The Variant-1 (with three degrees of freedom) of the composite position tolerance specification is the least constraining while variant-3 (with one degree of freedom) is most constraining. Also, it was found that the producibility of composite position tolerance specification is difficult to differentiate as the number of features in the pattern increases.