Study on a tolerance grading allocation method under uncertainty and quality oriented for remanufactured parts

Abstract

Limited by techniques, the process of remanufac- turing exists masses of uncertainties which have a great impact on the remanufactured parts quality, how to achieve a higher quality of mechanical products by using limited remanufactured parts precision, has become one of the key issues of remanufacturing industry. Firstly, with a target to reduce uncertainties and improve the quality of automatic products, a method of tolerance grading allocation for rema- nufactured parts is proposed based on the uncertainty anal- ysis of the remanufacturing assembly. The dimensional tolerances of the mechanical parts are divided into positive and negative two groups. We use selective assembly method to reduce assembling deviation. Then, the method is proven by mathematical formulas that the remanufactured parts variance can be expanded to two times, and the tolerances can be liberalized 40 % through tolerance grading allocation method. It is also the theoretical basis for improving the reuse radio and quantitatively describing the tolerance lib- eralization in this paper. Finally, feasibility research on this method is studied from the angle of cost-benefit. Further- more, a tolerance grading allocation example of remanufac- tured engine piston assembly in a power corporation shows the validity and practicality of the proposed method.