Application of X-S Control Cards to Parameter Control in the Machining Process of Piston Castings for Internal Combustion Engines

This article discusses the possibility of using a two-track X-S control card on a Mesas device to control the production process parameters of piston castings for combustion engines. The research was carried out at the Federal-Mogul Gorzyce company. The basis for estimating the variability of the process results from the mean value (X) is the standard deviation (S). Thanks to specially designed measuring stations that use algorithms to calculate process indicators (Cp and/or Cpk) and their visualization, the cost of manufacturing products and the number of non-compliant products (scraps) are reduced. The process stability was investigated by measuring the key dimensions of the piston casting in a specific population and a given measurement cycle. Taking into account the precision of details, their technical condition, and surface quality, the production machines and cutting tools were optimally selected. It has been found that an important element of the effective use of Statistical Process Control (SPC) are trained/experienced operators who can correctly interpret the resulting control chart forms.