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Nowadays, micro engine miniaturization is one of the most challenging issues, especially for the design and fabrication of the high-power-density micro Wankel engine. With the decrease of the size of the micro engine, the problem of the heat deformation of the cylinder becomes more serious. In this paper, a micro Wankel engine with microtextures on the outer surface of the cylinder is designed and manufactured to diffuse the heat dissipation and regulate the temperature gradient, so as to increase the power output density. First, a series of finite element simulations are conducted to design a type of ideal surface microtexture. Then, the machining condition is optimized to fabricate microtextures by micro cutting on the cylinder surface by studying the processing parameters. Finally, the performance of the new micro Wankel engine in terms of the temperature gradient regulation and the mechanical power output is tested and compared with that of the un-textured micro engine. The comparison results show that temperature of the textured micro engine was dropped from 185 °C to 125 °C and the mechanical power output increased by 10.74% from that of its un-textured counterpart, verifying the proposed methods for temperature gradient regulation.

In precision glass molding (PGM) of glass materials with a high melting point, heat treatment of nickel phosphorus (Ni–P) should be made in advance to eliminate mold deformation during the high temperature molding. During the process, crystallization occurs on the plating and crystalline Ni–P with a particular micro-machinability is generated. Burrs of large sizes with a fibrous structure are observed on the microgroove ridge during the study of the fly cutting microgrooving. The Poisson burr accumulation in each material removal period is considered as the reason for the burr formation and a model of the burr accumulation in fly cutting is established based on the concept of maximum effective cutting thickness. According to the model, a high feed rate leads to the restriction of burr formation while fracture pits tend to be generated on the microgroove ridge. The fracture pits caused by the brittle removal of the material could be eliminated through the feed rate adjustment of fly cutting. The optimal processing parameter is proposed in consideration of the burr formation restriction and the elimination of fracture pits. The efficiency of microgroove mold machining is significantly improved. A high-quality microgroove mold is fabricated and the serviceability of the mold is tested through a PGM experiment. [ABSTRACT FROM AUTHOR]