It has come to my attention that there are people out there purchasing CNC machines with contractual requirements for the machine to meet a Cpk prior to payment. Apparently, this is occurring in automotive circles (big surprise.) What an abject travesty of statistics. What is interesting is that in order to meet this incorrect application of statistics, the focus shifts immediately away from tool wear (the actual underlying process) and directly onto the algorithm for auto-compensation. It becomes the process...just like any over-controlling individual would be if they constantly adjusted their process to the target value. So, as the main source of variation, does anyone really understand their auto-compensation algorithm? Do you think you should??