I have a process that is affected by many variables (humidity, outside temp, pressure, many other small variables). We have set-up parameters defined (actually the last settings used when the specific product was run) that we use to set the intial run. Depending upon what the product looks like as it exits the process, these initial parameters are then tweaked to dial in the product characteristics. The product inspections are in the PCP as are the "key" process char's along with the "set-up" parameters. The set-up parameters are not in the PCP as on-going (after set-up) checks but there is a feedback loop from product inspection downstream - if the product char's move then the process char's can be adjusted. We DO NOT adjust the process based on many parameters if the product char's are running good. My question (finally) has to do with calibrations of some of the process parameter setting mechanisms. Most of these offer crude measurements (just to get the process "close" and then are dialed in per above process), are maintained through PM processes and any affect upon the final product is verifed with calibrated tools in product inspection. Does anyone see a reason for calibration of these of these process measurements?