Papers by Author: H.J. Liu

Abstract: Selective Laser Sintering (SLS) has many advantages such as fast building speed, wide range of materials, complicate shape of prototype and simple post-treatment. However, the shrinkage and mechanical stresses result in lost of the accuracy. This paper investigates the dimension precision of polymer SLS prototypes and proposes methods to control dimensions in suitable degree. The influencing factors of dimensional precision in the file preparation of CAD model, manufacturing system of SLS prototype and sintering process are analyzed. It indicates that the sintering shrinkage in sintering process is the main reason of dimensional changes. To improve the dimensional precision, the measures are proposed to diminish the shrinkage: improving material of prototype, optimizing the sintering process and compensating the lost of dimension. After analysis the experimental results, the rule of error changes is summarized by fitting equations and feedback to controlling software of SLS system to improve the dimensional precision effectively. The SLS prototype could be controlled in 100±0.20mm through compensation.

Abstract: In this paper, electrochemical finishing（ECF） is presented. Compared with conventional finishing technology, the characterization of surface topography machined by ECF and its effect on the performance, including friction coefficient, original wear and tear, precision durability, fatigue strength, contact stiffness, corrosion resistance and adhesiveness are analyzed and studied. Experimental results have testified that ECF can observably improve surface quality of parts and finally improve its physical mechanical performances and lifetime to a large extent.