I work for a U.S. Gov facility that is NADCAP certified, under AMS2430 (latest), and we use cast steel shot certified under AMS2431/1D. We also use "Frozen Processes" to maintain strict control of our process. We are not able to adjust any parameters that affect intensity without multiple levels of authorization. Our CNC machines are about 3 years old. We recently noticed intensity gradually climbing on some of our machines. We were out of our intensity limits in some cases. After looking at the obviuous possibilities, we had no choice but to conclude that we had an issue with the shot. We discovered through in-shop testing that brand new shot had about .0015A less intesity than well used shot. After shooting the new shot against a steel plate for about 2 hours, the intensity started climbing. I am unable to find any information on proper shot conditioning. Perhaps others in the industry simply adjust parameters when intensity climbs out of range, however we are bound by the frozen process controls. Also, the visual inspection in AMS-2430 condemns shot pieces that are considered "marginal" in AMS-2431/1. In other words, once I put brand new shot in my machine, what was acceptable is now unacceptable. I need a way of getting this new shot to acceptable condition visually as well as pre-conditioning to avoid that climb in intesity that comes with normal use. Is there a proper method for conditioning cast steel shot before use in actual production? Is there an issue that needs to be addressed regarding AMS-2430 vs AMS-2431/1?
