Selecting a better supplier by testing unilateral specification process capability indices C_PL and C_PU

摘要

To present a testing procedure that is convenient for practitioners to select the better suppliers step-by-step. The unilateral specification process capability indices C_PL and C_PU proposed by Kane (Ref. 1) are. where LSL is the lower specification limit, USL is the upper specification limit, μ is the process mean and σ is the process standard deviation. Under the assumption of a normal population, the relationship between process yield and the indice can be expressed by.