Mechanical Polishing Features And Principles

The role of polishing is to reduce the surface roughness of the workpiece, in order to obtain a bright, flat surface, this article is mainly for you to explain the characteristics of mechanical polishing and the principle.

Mechanical polishing is the use of flexible polishing tools and abrasive particles on the surface of the workpiece for finishing processing and deburring. Polishing can not improve the dimensional accuracy or geometric accuracy of the workpiece, but to get a smooth surface or mirror gloss for the purpose. Mechanical polishing relies on the grinding and tumbling action of very fine polishing powders to remove a very thin layer of metal from the abrasive surface of the specimen.

Mechanical polishing, polishing machine on the polishing wheel for high-speed rotation, the operator will be polished parts surface with the appropriate pressure pressed on the polishing wheel, when the role of friction and high temperature, so that the polished surface is prone to deformation and the formation of a layer of "processing deterioration layer". In the role of rotating friction, on the one hand, the surface of some convex part is cut, while the surface of the metal parts will also produce plastic deformation, convex parts are pressed, or move a distance to fill in the depressed parts. This cutting convex filling concave levelling process, with high speed repeatedly on a large scale, coupled with the polishing paste brightening effect, the result is to make the original rougher surface of the parts, become smooth and bright.

Polishing does not improve the dimensional or geometric accuracy of the workpiece, but aims to obtain a smooth surface or a mirror shine, sometimes also to eliminate the shine (matting). Mechanical polishing is usually carried out with a polishing wheel as a polishing tool. The polishing wheel is generally made of multi-layer canvas, non-woven fibres, felt or leather, with metal round plates clamped on both sides, and its wheel edge coated with polishing agent made of micronized abrasives and grease, etc. evenly mixed. Polishing, high-speed rotation of the polishing wheel (circumferential speed of 20 m / s or more) pressed to the workpiece, so that the abrasive on the surface of the workpiece to produce rolling and trace cutting, so as to obtain a bright processing surface, surface roughness is generally up to Ra0.63 ~ 0.01 microns; when the use of non-grease matting polishing agent, the bright surface can be matted to improve the appearance.

When rough polishing, a large number of steel balls, lime and abrasives are placed in an inclined can-shaped drum. When the drum is rotating, the steel balls and abrasives are randomly rolled and collided in the barrel to remove the convex front of the surface and reduce the surface roughness, which can remove a margin of about 0.01 mm.

Fine polishing in the barrel filled with steel balls and broken pieces of fur, continuous rotation for several hours can get a dazzling bright surface. The polishing of the precision linear ruler is carried out by immersing the processed surface in a polishing solution, which is made from a mixture of chromium oxide micro powder and emulsion with a particle size of W5 to W0.5. Polishing wheel using material uniformly fine by degreasing treatment of wood or special fine felt made of its movement track for uniform dense mesh, polishing the surface roughness is not greater than Ra0.01 micron, in the magnification of 40 times the microscope can not observe any surface defects. There are also methods such as electrolytic polishing.