Kinematic Analysis of Dimensional Variation Propagation for Multistage Machining Processes With General Fixture Layouts

Abstract

Recently, the modeling of variation propagation in complex multistage manufacturing processes has drawn significant attention. In this paper, a linear model is developed to describe the dimensional variation propagation of machining processes through kinematic analysis of the relationships among fixture error, datum error, machine geometric error, and the dimensional quality of the product. The developed modeling technique can handle general fixture layouts rather than being limited to a 3-2-1 layout case. The dimensional error accumulation and transformation within the multistage process are quantitatively described in this model. A systematic procedure to build the model is presented and validated. This model has great potential to be applied toward fault diagnosis and process design evaluation for complex machining processes. Note to Practitioners-Variation reduction is essential to improve process efficiency and product quality in order to gain a competitive advantage in manufacturing. Unfortunately, variation reduction presents difficult challenges, particularly for large-scale modern manufacturing processes. Due to the increasing complexity of products, modern manufacturing processes often involve multiple stations or operations. For example, multiple setups and operations are often needed in machining processes to finish the final product. When the workpiece passes through multiple stages, machining errors at each stage will be accumulated onto the workpiece and could further influence the subsequent operations. The variation accumulation and propagation pose significant challenges to final product variation analysis and reduction. This paper focuses on a systematic technique for the modeling of dimensional variation propagation in multistage machining processes. The relationship between typical process faults and product quality characteristics are established through a kinematics analysis. One salient feature of the proposed technique is that the interactions among different operations with general fixture layouts are captured systematically through the modeling of setup errors. This model has great potential to be applied to fault diagnosis and process design evaluation for a complex machining process