Abstract: Dr. TAGUCHI’s quality loss function is used to handle the selective assembly activity about mechanical product, in order to reduce the loss of mechanical product that can be affected by its function fluctuation after selective assembly. Through analyzing the disadvantages and limitation of the quality loss function proposed by Artiles, multi-quality- characteristic loss function based on signal noise ratio(SNR) is introduced, which expresses quantitatively each multi-quality- characteristic’s loss weight and loss cost of each part or component, and the quality loss function of matching deviation is proposed as weighing an effective index of matching precision. Concerning multi-mating precision of mechanical product and multi-quality characteristic of each part or component synthetically, the model of product-quality loss cost (P-QLC) facing on selective assembly is built by using thinking of integer plan, in case of guaranteeing the minimum of product quality loss cost, the goal of optimal assembly combination is achieved. An example is given to testify the validity of this method.

Key words: Precision of matching Selective assembly model of P-QLC, Quality loss function, Signal noise ratio