Abstract: The complex product manufacturing, e.g., autobody and engine, usually need dozens or even hundreds of manufacturing processes. Blank deviations, machine tool errors, jig positioning errors and errors by operating environment caused have been transfered, accumulated and formed product comprehensive deviation in the manufacturing process, and ultimately affect the product performance and market competitiveness. On the one hand, the manufacturing process station layout and process parameters are determined according to the product structure and quality requirements for technological design of the off-line quality control, on the other hand, the size deviation root caused and taked corresponding process control measures are determined at the instance of the size deviation in the manufacturing process for on-line quality control. Both complements promote the ascension of the manufacturing quality. Digital method play a key role in improving product accuracy of manufacturing. According to the theoretical and applied researches on the dimensional control of auto-body and engine, the scientific connotation and key techniques of dimensional control of complex products is explained. The general frame-work of digital dimensional control methods for manufacturing complex products is proposed based on the stream of variation theory(SOV), which describes the laws of generation, transmission, accumulation and absorption of variations in multi-station manufacturing processes. Then, the two-stage dimensional control of complex product is summarized. In the stage of product process development, the digital process design method is used to synthesize the product and tooling tolerance. In the stage of product manufacturing, the data-driven process control method is used to improve the process stability. Some thoughts are given on the development and trend of quality control techniques for high-end equipment and high performance products.

Key words: Auto-body, Automobile engine, Complex product, Digital process design, Quality control