CNC polishing

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. It is a modification process on the surface of the workpiece by using polishing tools and abrasive particles or other polishing media.

Polishing does not improve the dimensional accuracy or geometric shape accuracy of the workpiece, but is aimed at obtaining a smooth surface or mirror gloss, and is sometimes 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 with metal discs, and the rim is coated with a polishing agent evenly mixed with micropowder abrasives and grease.

During polishing, the high-speed rotating polishing wheel (circumferential speed above 20 m/s) presses against the workpiece, causing the abrasive to roll and micro-cut the surface of the workpiece, so as to obtain a bright processed surface, and the surface roughness can generally reach Ra0.63 ~0.01 microns; When using a non-greasy matting polish, it can matt a bright surface to improve appearance. When producing bearing steel balls in large quantities, the method of drum polishing is often used.

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

When finely polishing, put steel balls and fur fragments into the wooden barrel, and turn it continuously for several hours to get a dazzling and bright surface. The polishing of the precision linear scale is carried out by immersing the processed surface in the polishing liquid, which is made of chromium oxide powder with a particle size of W5-W0.5 and an emulsion. The polishing wheel is made of even and fine degreased wood or special fine felt. Its motion trajectory is uniform and dense mesh. The surface roughness after polishing is not greater than Ra0.01 micron. Observe under a microscope with a magnification of 40 times. Less than any surface defects. In addition, there are methods such as electrolytic polishing.