Track: Quality Control and Quality Management

Abstract

As technologies develop rapidly nowadays, managing and improving the quality of products have become important issues in manufacturing industries. Acceptance sampling plan is a quality management tool which has been commonly used in practice to provide reliable decision rules in lot sentencing. Owing to the availability and efficiency of acceptance sampling plan, various acceptance sampling plans are proposed to handle different situations. Skip-lot sampling plan (SKSP) has been used extensively in the manufacturing industries for inspecting a successive series of lots or bulk materials. It takes the quality history into consideration and inspects only a fraction of the submitted lot. On the other hand, repetitive group sampling plan (RGSP) gives the submitted lots the chance of resampling which is helpful for maintaining long-term cooperation between the producer and the consumer. Compared with single sampling plan (SSP), both SKSP and RGSP can obtain a smaller average sample number (ASN) in inspection. 

Process capability indices (PCIs) is another common tool in the field of quality management that has been used to measure the performance of manufacturing process. The advantage of PCIs is that it is a dimensionless tool and is useful to quantify the process capability. Among PCIs, Cpk is the most popular one in manufacturing industries because it not only considers both precision and accuracy of the process but also gives the estimation of the process yield. In recent years, scholars have applied PCIs in acceptance sampling plans. The PCI-based sampling plan can improve accuracy of inspection by using the exact sampling distribution. To consolidate the advantage of SKSP, RGSP and PCIs, this study develops a modified version of SKSP based on Cpk where RGSP is used as the reference plan.  The optimization model of the proposed plan is constructed to minimize the average sample number and fulfill the quality and risk requirements by both producers and consumers. Moreover, the performance of the proposed plan are compared with the conventional SSP and SKSP.