Abstract: Effective production process management contributes to the competitiveness of a company. If a manufacturer knows customer requirements to produced goods he can define specification levels for a product at each production process. Therefore, a complex index is required which allows to evaluate process quality quantitatively depending on the extent of its shift and dispersion. The tool widely used for assessing process quality is capability index. The analysis presented in the paper shows that this index has two drawbacks: it does not consider costs level and process change dynamics. To solve this problem we introduced two additional indices. One index based on the calculation of economic losses, and the second one considers process change dynamics. Developed quality indices can be applied for the cases when a production process follows the Gaussian law. Moreover, Q index should be used in the cases when the probability of nondefective units production is high.
Keywords: quality in engineering, capability index, tolerance limits
Recieved: 17.11.2016 Accepted: 29.03.2017 UDC: 005.6