Having determined the quality problems in mass production in a medium-size firm chosen as a pilot study, all the processes from casting to machining were investigated. The problem of low quality arising during production was eliminated by the statistical quality control of a given product. The procedure to eliminate the problem of low quality followed a specified procedural sequence. The beginning stage of the problem was analyzed, the type of the quality problem was identified, some short-term corrective measures were sought and the required means of measurement and control were prepared. Samples were chosen randomly during the production process. X-R control charts were used with the support of statistical calculations for the problem of low quality concerning the part and undesired size causing high costs. The underlying reasons for parts not meeting the desired quality were identified and the correct parameters presented.