The product price is the combination of a reflection of interest balance and a comprehensive understanding of product performance and quality between manufacturing vendors and users, which can be used directly to measure the loss that brought to society after entering the market. Therefore, a piecewise linear quality loss model (hereinafter referred to as the price model) was developed. The outer diameter of the iron core were taken in micro-motor as an example to explore the influence of the important parameters in the model on iron core quality loss, and to contrast with Taguchi quality loss model. The results show that the price model is more realistic than Taguchi quality loss model. The new price model provides the condition for product tolerance optimization design, and enriches the content of the field of quality loss.