Process Capability Evaluation for a PVC Pipe Product Family

Process capability indices can be viewed as convenient and excellent tools to measure and define process output. Several capability indices including C_p, C_pu, C_pl, C_pk, C_pm and C_pp have been widely used in manufacturing industry to provide common quantitative measures on process potentials and performance. Process capability inex C_pp can be used to measure product capability with respect to process targeting. “The larger the better” is the general rule for the application of process capability indices C_p, C_pu, C_pl, C_pk and C_pm. However, those researchers take accounts for processes with single quality characteristics only and cannot be applied to a product family with different models, types or sizes simultaneously. the approach of this paper is to propose a concise and applicable methodology that measures the entire process capability of a product family with several models. For convenient and practical application to product engineers, a simple procedure of hypothesis test for entire process capability of a PVC pipe product familiy is well established.