Evaluation on the Accuracy of Multiple Machines using Composite Position Tolerances

Open Access
- Author:
- Jiang, Yiran
- Graduate Program:
- Industrial Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- July 13, 2016
- Committee Members:
- El Amine Lehtihet, Thesis Advisor/Co-Advisor
- Keywords:
- Composite Position Tolerance
Producibility
Accuracy - Abstract:
- This thesis evaluates the producibility of the three (3) composite position tolerance variants and the accuracy of a set of production engineering equipment including subtractive and additive manufacturing processes. These processes included two CNC machining centers, a Fortus 250mc RP machine and an Objet30 Prime RP machine in the Industrial and Manufacturing Engineering Department at the Pennsylvania State University. A set of circular, rectangular, and linear patterns of holes was designed and produced on each machine with three (3) replications. Two dimensional position and size data of the holes was collected using a coordinate measuring machine and used to estimate the minimum composite position tolerance values that will satisfy a given pattern. These values were then used to differentiate between the accuracy of the four machines and assess the producibility of the composition tolerance constraints across several dimensions such as variants, patterns and number of features in the pattern. It was found that the Fortus 250mc RP machine had the worst accuracy while the other three machines were mixed. However, by separating the patterns, it was found that the new CNC machining center dominated or performed best for the circular pattern, while the Objet30 Prime RP machine dominated at the rectangular pattern due to the structure of the nozzles in the printing head. The Objet30 Prime also dominated at the linear patterns, but the results of the two CNC machining centers were mixed due to differences in the performance of machines axes. The producibility of the composite position tolerance became more difficult as the variants became more constraining and the number of feature in a pattern increased for all machines and patterns. The circular and rectangular patterns showed a more difficult producibility of the composite position tolerance than the linear patterns.