1. Abrasive material:
The commonly used abrasives for cutting wheels include brown corundum (A), white corundum (WA), black corundum (BA), black silicon carbide (c), etc. The most commonly used is brown corundum, because brown corundum has high hardness, toughness, and particles. Sharpness, strong applicability and lower price than other abrasives. Brown corundum is divided into primary sand and secondary sand according to whether it is fully reduced during smelting or not, mainly in terms of chemical composition: Al2O3 content of primary sand ≥94.5; Al2O3 content of secondary sand <94.5%; generally 85% The content of Fe2O3 is about 4% to 5%; therefore, the hardness of secondary sand is lower than that of primary sand, but the price is also lower; brown corundum is suitable for processing various carbon steels and general alloy steels; white corundum is harder than brown corundum, It has high brittleness and low grinding heat. Because of its high price, it is used when the workpiece requires small thermal deformation. It is also used as a mixed abrasive for special material processing; the content of Al2O3 in black corundum is 70-85%, and the content of Fe203 is 7-9% , Low hardness, poor cutting force, but also cheap; black silicon carbide has high hardness and good brittleness, sharp cutting edge, good self-sharpening performance, good thermal conductivity, and has advantages in processing non-ferrous metals, plastics, rubber and cast iron.
2. Abrasive particle size:
The commonly used particle size is 22#-80#, and the cutting efficiency is low when the particle size is fine.
The choice of abrasive particle size is mainly related to surface roughness and productivity. In rough grinding, the grinding allowance is large and the required surface roughness value is larger, so coarser abrasive grains should be used. Because the abrasive grains are coarse, the pores are large, the grinding depth can be larger, and the grinding wheel is not easy to block and heat up. In fine grinding, the margin is small, and the roughness value is required to be low, so finer abrasive grains can be selected. Generally speaking, the finer the abrasive grains, the better the grinding surface roughness.
3. Grinding wheel hardness:
Common hardness: P, Q, R; N, S; generally use a harder grinding wheel to reduce the wear of the grinding wheel. Its hardness is controlled by factors such as the amount of bonding agent, molding density, firing temperature and firing time.
Commonly used resin binders are: powdered phenolic resin and liquid phenolic resin. The powdered phenolic resin has good manufacturability, the molding density of the abrasive tool is slightly smaller, the organization number is slightly larger, and the price is higher than that of the liquid phenolic resin; the price of the liquid phenolic resin is low, but the material is easy to agglomerate and the material is not uniformly mixed, which is easy to cause the abrasive tool to be localized hard.
The organization number of the cutting wheel should be slightly larger to improve the cutting efficiency: too large and affect the strength, the commonly used organization number is 3-7.
Factors Affecting the Performance of Grinding wheel?
1. Abrasive material: