Abstract
Acceptance sampling plans can provide the vendor and the buyer a decision rule for lot sentencing to meet their requirements of product quality. One of them is two-plan sampling system, which consists of single sampling plans with normal and tightened inspections. The system begins from tightened inspection, and switch to normal inspection if lots in a raw are all accepted. Then if there is an additional lot is rejected in the next lots after a rejection under normal inspection, it needs to turn back to tightened inspection. Therefore, it is also called tightened-normal- tightened (TNT) sampling system. Process capability indices can provide measures on the ability of reproducing product units that meet the specifications, and the widely used capability indices are and ( and ). So, several variables single sampling plans have been developed based on process capability indices for controlling the lot or process fraction defective recently. For above reasons, we developed a variables TNT sampling system with new type in this paper. It can be divided into two parts, one is based on and the other one is based on . Combining two kinds of process capability indices can enhance the practical value of this paper. The results of sampling systems indicate that the proposed sampling system is more efficient and flexible than traditional acceptance sampling plans. Lastly, we analyzed a practical case to assist users to learn more from the proposed sampling systems.