Analysis and avoidance of flow-induced defects in meso-forming process: simulation and experiment

Abstract

In the current metal-forming industries, productivity, product quality, and production cost are three overriding issues. Product quality, however, is the most critical issue and the designed forming process must be able to produce the quality parts with desirable geometries and without defects. In micro- and meso-forming processes, the formation mechanism of flow-induced defects has not yet been fully investigated. In this paper, the flow-induced defects in meso-forming of a designed part are investigated and the defect formation mechanisms are explored and revealed via the finite element simulation of the entire process. To develop a defect-free forming process, a feature-based method for defect-free process design is proposed to identify the best forming sequence/process for defect-free deformation. By employing the proposed method, two meso-forming processes, viz., four steps extrusion and backward extrusion, are proposed to fabricate the designed part without folding defects. The applicability of the meso-forming processes for defect avoidance is verified by numerical simulation and physical experiment. The experiments also corroborate the findings of finite element simulations. On the other hand, the proposed feature-based method is further verified by the effectiveness of the generated two meso-forming processes for their efficiency in forming of the meso-scaled part without the flow-induced defects.