Error cancellation modeling and its application to machining process control

The product quality in a machining process can be affected by datum surface imperfections, fixture locator errors, and machine tool errors. It has been previously observed that these effects can cancel out one another for certain features. The mathematical modeling and analysis of this phenomenon is currently an open issue. We use the concept of an Equivalent Fixture Error (EFE) embedded into a modeling methodology to obtain insights into this fundamental phenomenon and achieve an improved process control. Based on our process fault model we develop a sequential root-cause identification procedure and EFE compensation methodology. A case study is presented to demonstrate the proposed diagnostic procedure. A simulation study is also performed to illustrate the error compensation procedure.