Part polishing

Machining parts polishing refers to the use of mechanical, chemical or electrochemical action to reduce the surface roughness of the workpiece to obtain a bright and smooth surface.

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It is the modification of the surface of the workpiece with polishing tools and abrasive particles or other polishing media.

Machining parts polishing does not improve the dimensional accuracy or geometric accuracy of the workpiece, but is for the purpose of obtaining a smooth surface or specular gloss, and sometimes it is also used to eliminate gloss (matting). Usually a polishing wheel is used as a polishing tool. The polishing wheel is generally made of multiple layers of canvas, felt or leather, and the two sides are clamped by metal discs.

When the machining parts are polished, the high-speed rotating polishing wheel (the peripheral speed is above 20 m/s) is pressed against the workpiece, so that the abrasive can roll and micro-cut the surface of the workpiece, so as to obtain a bright machined surface, and the surface roughness can generally reach Ra0 .63 ~ 0.01 microns; when a non-greasy matting polish is used, it can matt the bright surface to improve the appearance. In mass production of bearing steel balls, drum polishing is often used.



During rough throwing, a large number of steel balls, lime and abrasives are placed in an inclined tank drum. When the drum rotates, the steel balls and abrasives are randomly rolled and collided in the drum to remove the convex front and reduce the surface roughness. For this purpose, a margin of about 0.01 mm can be removed.

For fine polishing, the barrels are filled with steel balls and pieces of fur, and rotated for hours to obtain a dazzling surface. The polishing of the precision linear ruler is carried out by immersing the machined surface in a polishing liquid, which is composed of a mixture of chromium oxide powder with a particle size of W5-W0.5 and an emulsion. The polishing wheel is made of finely degreased wood or special fine felt. Its motion trajectory is a uniform and dense mesh. The surface roughness after polishing is not greater than Ra0.01 micron. Observe it under a microscope with a magnification of 40 times. No surface defects. In addition, there are methods such as electrolytic polishing.

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Source: @cyanbat   Author: cyanbat

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