A. The particle size of grinding wheel: Considering from the geometrical factor, the finer the particle size of grinding wheel, the smaller the surface roughness value of workpieces. But if abrasive grain is too fine, grinding wheel will be easy to be blocked by abrasive dust. If the heat conduction is bad, it will cause burns and other phenomena, which can make surface roughness value of the machining surface increased . As a result, the particle sizes of grinding wheel are often selected from No.46 ~ 60.

B. The hardness of grinding wheel: If grinding wheel is too hard, abrasive grains will be not easy to fall off, which can make the surface roughness value increased. If grinding wheel is too soft, abrasive grain will fall off easily. Therefore, the grinding effect is abated, and it will also make the surface roughness value increased. As a result, soft grinding wheels are selected.

C. The organization of grinding wheel: There are large abrasive grain proportion and small pores, and it can obtain smaller surface roughness values when forming grinding and precision grinding. Grinding wheel with loose organization is not easy to be blocked, suitable for grinding soft metal, non-metallic materials and heat sensitive materials (magnetic steel, stainless steel, heat-resistant steel, etc.), and can obtain smaller surface roughness values. Under normal circumstances, we should select some grinding wheel with medium organization.

D. Grinding wheel materials: If we select appropriate grinding wheel materials, we can obtain satisfactory surface roughness. Oxide (corundum) grinding wheel is suitable for grinding steel parts; Carbide(silicon carbide, boron carbide) grinding wheels are suitable for grinding cast iron, cemented carbide and other materials; Superhard materials (synthetic diamond and cubic boron nitride) grinding wheel grinding can obtain small surface roughness values, but the processing cost is higher.

E. The grinding wheel dressing: The grinding wheel dressing also has important influence on the surface roughness. Fine dressed grinding wheel can effectively reduce the surface roughness of workpieces. In addition, the nature of the workpiece material and the selection of cooling lubricant also have obvious influence on the grinding surface roughness.