Capability measurement of manufacturing processes creates basic attributes for the production of conformity products, those that meet the necessary conditions in terms of tolerance limits for all important parameters.

They are also important in the supplier-customer relationships context as one of the important easily predictable but highly effective indicators of the quality production of delivered products.

In many manufacturing companies, the capability measurement is performed by using capability indicators, where the method of calculation is based on the assumption of normality of the distribution of the measured product parameter, as well as the assumption of constant median value but also variability during the monitored period.

However, in practice we often are able to see such parameters of manufacturing products or processes, which do not meet the expectations required in the classical method of capability indexes calculation.

The problems are usually in a different than normal models of the distribution of a random variable representing a specific parameter of a product or process, as well as in the excessive variability of median values ​​during the time in these so-called non-standard parameters.

There will be presented on the particular manufacturing product, how certain non-conformities occur during the capability indexes measurement indices in the classical way for selected non-standard parameters.

The paper describes how it is possible to modify the common method of calculating the mentioned capability indexes in a simple way so that they are applicable in specific production conditions. There will be also presented a basic strategy for process evaluation methods that will help identify these non-standard parameters.