The particle size selection of the grinding disc mainly depends on the following factors:
** I. Initial surface condition **
1. If the surface of the grinding object is very rough, there are obvious scratches, bumps or a large number of processing marks, you should first choose a coarse-grained grinding piece, such as 40-80 mesh. This can quickly remove a large amount of material and initially smooth the surface.
2. For objects with relatively good surface condition and only slight defects or shallow scratches, you can start from 120-180 grain sizes.
** Two, the final grinding accuracy requirements **
1. If very high surface accuracy and finish, such as mirror effect, should be selected in the final grinding stage of extremely fine-grained grinding pieces, usually in 1500-3000 mesh or even higher.
2. For general accuracy requirements, such as removing small scratches, making the surface smooth but not requiring the degree of mirror, 800-1200 grain size may be sufficient.
** Three, material hardness **
1. For materials with higher hardness, such as cemented carbide, ceramics, etc., it may be necessary to use coarse-grained grinding pieces, such as 60-100 mesh, in the initial grinding to effectively remove the material. As the grinding progresses, the particle size is gradually reduced.
2. For softer materials, such as aluminum, copper, etc., coarser particle size may cause excessive wear and surface deformation, you can start with a relatively fine particle size, such as 100-150 mesh.
Four, grinding stage **
1. Rough grinding stage: Usually choose 40-120 purpose grinding pieces, the purpose is to quickly remove excess materials and large defects.
2. Middle grinding stage: Use 180-400 purpose grinding pieces to further smooth the surface and reduce the marks left by rough grinding.
3. Fine grinding stage: 600-1200 grinding pieces are used to make the surface more smooth and delicate.
4. Polishing stage: Select ultra-fine grinding pieces or polishing paste of more than 1500 mesh to achieve a high-gloss surface.
For example:
When grinding a metal mold with high hardness, if there are deep processing marks and irregularity on the surface of the mold, 80 purpose diamond grinding sheets can be used in the rough grinding stage; In the middle grinding stage, 240 mesh grinding plates were used. The grinding stage uses 600 mesh grinding pieces; Finally, in the polishing stage, 2000 mg cerium oxide polishing paste is used to obtain a smooth, mirror-like surface.
As well as:
For grinding a soft aluminum alloy sheet, 120 mesh aluminum oxide grinding pieces can be selected in the initial stage, 320 mesh for medium grinding and 800 mesh for fine grinding to achieve better results.