国产爆乳无码一区二区麻豆,欧美牲交a欧美牲交aⅴ免费真,男人扒开女人双腿猛进视频,亚洲综合色一区二区三区


Chemical polishing


Chemical polishing is to allow the microscopic convex parts of the surface of the material to be dissolved preferentially in the chemical medium than the concave parts, thereby obtaining a smooth surface. The main advantage of this method is that it does not require complex equipment, can polish workpieces with complex shapes, and can polish many workpieces at the same time, with high efficiency. The core issue of chemical polishing is the preparation of polishing fluid. The surface roughness obtained by chemical polishing is generally several 10 μm.

More News