The supply crisis has affected social life in almost all sectors. A supply crisis can be avoided or reduced significantly by employing a risk analysis and derived measures as a part of quality management. The present paper researches two polypropylene materials. The aim of this study is to provide answers and possibilities on how to reduce the risk of material shortage in the plastics industry without having to adapt the moulding tool and the process parameters of the injection moulding machine. This metrological study was executed with ultrasonic sensor housings of the automotive industry. To interpret the results accurately, two approaches are in pursuit, technical relevancy, and statistical significance. Both will be described in detail, with the contemplation and interpretation of the results. The statistical significance, as a method of the Six Sigma toolbox, employs the 95% confidence level, the null-hypothesis and the t-test.