Abstract: In constrained-surface projection based stereolithography process, a significant pulling-up force is requuied to separate the cured part from the bottom surface of the resin vat, which reduces the throughput and reliability of the process. In order to solve the problem, a method for the separation force reduction by taking the micro-textured PDMS film as constraint substrate is proposed. The bilinear cohesive constitutive model was used to simulate the separation process of the cured layer from the substrate, and the effects of micro-texture characteristics involving geometry shape, area ratio and height on the adhesion force were investigated. The simulation results show that compared with the micro-textures with circular and square section shape, the micro-texture of triangular is more conducive to reduce the adhesion force; the adhesion force increases with the increase of the texture area ratio and the texture height shows an insignificant effect on adhesion force. PDMS films with different texture shape and spacing are prepared through silicon-based mold ICP etching combined with cast molding process and then the effects of micro-texture geometry features of substrate on separation force of solidified layer are studied experimentally. The experimental results agree well with the numerical calculation results. Under the optimal texture characteristics (micro-texture with triangular cross section, texture with spacing of 15 μm and height of 10 μm), the separation force of the cured layer from the textured substrate surface is reduced by about 60% compared with the flat film on the substrate.

Key words: constrained-surface projection based stereolithography, separation force, cohesive zone model, numerical simulation, micro-texture