The choice of abrasive (the choice of abrasive mainly depends on the workpiece material and heat treatment method)
- When grinding materials with high tensile strength, use abrasive materials with high toughness.
- When grinding materials with low hardness and high elongation, use brittle abrasives.
- When grinding materials with high hardness, use abrasives with higher hardness.
- Use abrasives that are not easily chemically reacted by the material being processed.
The most commonly used abrasives for Sharon are brown corundum (A) and white corundum (WA), followed by black silicon carbide (C) and green silicon carbide (GC), and the rest commonly used are chrome corundum (PA) and single crystal corundum ( SA), microcrystalline corundum (MA), zirconium corundum (ZA).
- Brown corundum grinding wheel: Brown corundum has high hardness and high toughness, suitable for grinding metals with high tensile strength, such as carbon steel, alloy steel, malleable cast iron, hard bronze, etc. This abrasive has good grinding performance and wide adaptability. It is commonly used to cut off rough grinding with a large margin, is cheap, and can be widely used.
- White corundum grinding wheel: The hardness of white corundum is slightly higher than that of brown corundum, and the toughness is lower than that of brown corundum. When grinding, the abrasive particles are easily broken. Therefore, the grinding heat is small, and it is suitable for the manufacture of fine grinding hardened steel, high carbon steel, The cost of high-speed steel and grinding wheels for grinding thin-walled parts is higher than that of brown corundum.
- Black silicon carbide grinding wheel: Black silicon carbide is brittle and sharp, and has higher hardness than white corundum. It is suitable for grinding materials with low mechanical strength, such as cast iron, brass, aluminum and refractory materials.
- Green silicon carbide grinding wheel: Green silicon carbide has higher hardness and brittleness than black silicon carbide, sharp abrasive particles, good thermal conductivity, suitable for grinding hard and brittle materials such as cemented carbide, optical glass, ceramics and so on.
- Chrome corundum grinding wheel: suitable for grinding workpieces with high surface quality requirements such as cutting tools, measuring tools, meters, threads, etc.
- Single crystal corundum grinding wheel: suitable for grinding stainless steel, high vanadium high speed steel and other materials with high toughness and high hardness and workpieces that are easily deformed and burned.
- Microcrystalline corundum grinding wheel: suitable for grinding stainless steel, bearing steel and special nodular cast iron, etc., used for forming grinding, plunge grinding and mirror grinding.
- Zirconium corundum grinding wheel: suitable for grinding austenitic stainless steel, titanium alloy, heat-resistant alloy, especially for heavy-duty grinding.
The choice of particle size (mainly depends on the surface roughness and grinding efficiency of the workpiece to be ground)
The particle size refers to the particle size of the abrasive, and the size is expressed by the particle size number
When grinding with a coarse-grained grinding wheel with a surface grinder, the production efficiency is high, but the surface of the workpiece is rough. When grinding with a fine-grained grinding wheel, the surface roughness of the workpiece is good, but the productivity is low. Under the premise of meeting the roughness requirements, the coarse-grained grinding wheels should be selected as much as possible to ensure higher grinding efficiency. Generally, coarse-grained wheels are used for rough grinding, and fine-grained wheels are used for fine grinding.
When the contact area between the grinding wheel and the workpiece is large, a coarser grinding wheel should be selected. For example, to grind the same plane, the grinding of the end face of the grinding wheel is coarser than the grinding of the grinding wheel.
The choice of hardness (mainly depends on the workpiece material to be ground, the grinding efficiency and the quality of the processed surface)
Hardness refers to the degree of difficulty of the grinding wheel falling off under the action of external force.In order to meet the requirements of different workpiece materials, the grinding wheel is divided into different hardness grades when manufacturing the grinding wheel
The grinding wheel is too hard, the blunt abrasive particles are not easy to fall off, the grinding wheel is easy to block, the grinding heat is increased, the workpiece is easy to burn, the grinding efficiency is low, which affects the surface quality of the workpiece; the grinding wheel is too soft, the abrasive particles fall off when they are sharp , Increased grinding wheel loss, easy to lose the correct geometry, affecting the accuracy of the workpiece. Therefore, the selection of the hardness of the grinding wheel should be appropriate, and it should be comprehensively considered according to factors such as the size of the contact area between the grinding wheel and the workpiece, the shape of the workpiece, the grinding method, the cooling method, and the type of the bonding agent of the grinding wheel.
- When grinding soft materials, choose a harder grinding wheel, when grinding hard materials, choose a soft grinding wheel;
- When grinding soft and tough nonferrous metals, the hardness should be selected to be softer;
- For materials with poor thermal conductivity, softer wheels should be selected;
- When face grinding is better than circumferential grinding, the hardness of the grinding wheel should be softer;
- Under the same grinding conditions, the hardness of the resin bond grinding wheel is 1 to 2 smaller than that of the ceramic bond grinding wheel;
- When the rotation speed of the grinding wheel is high, the hardness of the grinding wheel can be selected from soft grades 1 to 2;
- Grinding with coolant is 1 to 2 smaller than the hardness of the grinding wheel during dry grinding.
- The choice of bonding agent (should be considered according to the grinding method, speed and surface processing requirements and other conditions)
The most commonly used grinding wheel bond for bristle bricks are ceramic bond (V) and resin bond (B).
Ceramic bonding agent is an inorganic bonding agent with stable chemical properties, good heat resistance and corrosion resistance, and large porosity. The grinding wheel made of this bonding agent has high grinding efficiency and low wear, which can better maintain the geometry of the grinding wheel. , The most widely used. Suitable for grinding ordinary carbon steel, alloy steel, stainless steel, cast iron, cemented carbide, non-ferrous metals, etc. However, the ceramic bond wheel is brittle and cannot be subjected to severe vibration. Generally, it can only be used at a speed within 35 meters/second.
Resin bond is an organic bond. The grinding wheel manufactured by this bond has high strength, certain elasticity, low heat resistance, good self-sharpness, easy manufacture, and short process cycle. It can manufacture grinding wheels with working speed higher than 50m/s and very thin grinding wheels. Its scope of application is second only to ceramic bonding agents, and it is widely used for rough grinding, rough grinding, cutting and free grinding, such as grinding steel ingots and casting burrs. It can manufacture high-speed, high-finish grinding wheels, heavy-duty, cut-off and various special requirements.
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