Ph.D. Proposal Presentation by Austin H. Chen
Tuesday, September 14, 2004

(Dr. Thomas R. Kurfess, Chair)

"Process Control and Calibration For Precision Part Production"


The failure to meet desired dimensional tolerances in precision manufacturing is oftentimes costly. Certain designs may require parts to be manufactured from expensive or exotic materials. This makes it all the more critical that the part is not scrapped due to dimensional nonconformity. The task of manufacturing components to such tight tolerances is challenging on its own, but the task is compounded by the requirement of being repeatable. This research seeks to develop an appropriate strategy to identify sources of error in machining and to implement methods to increase workpiece acceptance by monitoring machine performance.

The goal of this research is to improve the precision of a standard 2-axis CNC machining center when machining a hemispherical component. The object of interest will be machined on the 2-axis CNC vertical machining center. Various error sources will be characterized and included in an error budget. Errors will be measured with the aid of a precision instrumentation such as a laser interferometer and ballbar. Data from intermittent on machine inspection of the part (using a touch probe) will be analyzed as a process check. The objective of this research is to first extend upon the concept of an error budget to characterize the various sources of error and how they affect part quality. A methodology will be developed for the identification of the factors that need to be considered when attempting to machine to a certain tolerance. Then, a relational algorithm or model will be developed for the purposes of relating the various factors of interest and as a means to monitor these factors, make any last minute adjustments before making the finishing cut, and predict final part quality.