How to select grinding fluid in different grinding methods?
During metal grinding process, it is very important to choose the right grinding fluid in order to obtain the ideal machining accuracy and surface quality. Different metal grinding processes have different processing phenomena and different requirements on grinding fluid, so the grinding fluid used is more different.
Selection of water-based grinding fluid
1.1 Ordinary grinding
It is recommended to use common emulsified grinding fluid with a dilution concentration of 2% to 5%, which is made up of rust inhibitor, emulsifier and mineral oil. Common grinding includes outer grinding, inner grinding, cone grinding, plane grinding, etc. According to the different grinding wheel size and grinding amount, it can be divided into rough grinding and fine grinding. Rough grinding machining accuracy requirements are not high, the machining dimension tolerance level is IT8 ~ IT7, the surface roughness is 0.8 ~ 0.4 μm. Fine grinding can obtain higher machining accuracy and lower roughness. The tolerance level of machining dimension is IT6 ~ IT5, and the surface roughness is 0.4 ~ 0.1μm. In the grinding process, the grinding wheel linear speed is generally 30 ~ 35 m/s. During grinding, a large number of fine metal debris and fine grains from grinding wheel threshing are produced, which are easy to stick to the surface of grinding wheel and workpiece, and damage the quality of the machining surface. The general grinding process requires good cleaning and cooling properties of cutting fluid, and both antirust and lubrication properties.
1.2 High Speed grinding
Water-based grinding fluid is suitable for high speed grinding. In metal grinding, the grinding wheel with linear speed over 50 m/s is usually called high speed grinding. The difference between high speed grinding and ordinary grinding is that, with the increase of grinding wheel linear velocity, the abrasive number of grinding wheel passing through the grinding area per unit time increases, and the friction times between grinding wheel and workpiece increases under certain feeding conditions, so that the heat generated per unit time also increases, and the grinding temperature increases significantly. The grinding temperature (average working temperature) is about 50% ~ 70% higher than that of 30 m/s when the grinding wheel linear velocity is 60 m/s.
The grinding temperature at 80 m/s is 15% ~ 20% higher than that at 60m/s. With the increase of workpiece temperature, the possibility of burning and forming cracks on the workpiece machining surface increases, and the machining size error increases. As the grinding wheel linear velocity increases, the cutting thickness of the abrasive becomes thinner under a certain amount of metal grinding per unit time. Under high temperature and high contact pressure, the abrasive materials adhere to the abrasive particles, and the chips will be embedded in the pores of the grinding wheel, resulting in blocked and blunt pores on the surface of the grinding wheel, thus reducing the grinding efficiency.
Therefore, ordinary grinding fluid can not be used in high speed grinding processing, but the grinding fluid with good penetration performance, cooling performance, extreme pressure lubrication performance, rust resistance, settling performance and cleaning performance can be used to quickly wash the waste debris generated and settle quickly, to meet the requirements of the processing technology. In addition, due to high efficiency and high heat output, high speed grinding requires high cooling and lubrication performance of grinding fluid. The heat transfer effect of the oil-based grinding fluid is poor, and the temperature of the grinding area is too high, which will lead to smoke phenomenon of the grinding fluid, resulting in environmental pollution of the working area. Moreover, due to the insufficient cooling of the oil-based grinding fluid, the surface of the workpiece is often burned. The cooling effect of water-based grinding fluid is better than that of oil-based grinding because of its high moisture content.
Selection of water-based grinding fluid
1.1 Ordinary grinding
It is recommended to use common emulsified grinding fluid with a dilution concentration of 2% to 5%, which is made up of rust inhibitor, emulsifier and mineral oil. Common grinding includes outer grinding, inner grinding, cone grinding, plane grinding, etc. According to the different grinding wheel size and grinding amount, it can be divided into rough grinding and fine grinding. Rough grinding machining accuracy requirements are not high, the machining dimension tolerance level is IT8 ~ IT7, the surface roughness is 0.8 ~ 0.4 μm; Fine grinding can obtain higher machining accuracy and lower roughness. The tolerance level of machining dimension is IT6 ~ IT5, and the surface roughness is 0.4 ~ 0.1μm. In the grinding process, the grinding wheel linear speed is generally 30 ~ 35 m/s. During grinding, a large number of fine metal debris and fine grains from grinding wheel threshing are produced, which are easy to stick to the surface of grinding wheel and workpiece, and damage the quality of the machining surface. The general grinding process requires good cleaning and cooling properties of cutting fluid, and both antirust and lubrication properties.
1.2 High Speed grinding
Water-based grinding fluid is suitable for high speed grinding. In metal grinding, the grinding wheel with linear speed over 50 m/s is usually called high speed grinding. The difference between high speed grinding and ordinary grinding is that, with the increase of grinding wheel linear velocity, the abrasive number of grinding wheel passing through the grinding area per unit time increases, and the friction times between grinding wheel and workpiece increases under certain feeding conditions, so that the heat generated per unit time also increases, and the grinding temperature increases significantly. The grinding temperature (average working temperature) is about 50% ~ 70% higher than that of 30 m/s when the grinding wheel linear velocity is 60 m/s. The grinding temperature at 80 m/s is 15% ~ 20% higher than that at 60m/s. With the increase of workpiece temperature, the possibility of burning and forming cracks on the workpiece machining surface increases, and the machining size error increases. As the grinding wheel linear velocity increases, the cutting thickness of the abrasive becomes thinner under a certain amount of metal grinding per unit time. Under high temperature and high contact pressure, the abrasive materials adhere to the abrasive particles, and the chips will be embedded in the pores of the grinding wheel, resulting in blocked and blunt pores on the surface of the grinding wheel, thus reducing the grinding efficiency. Therefore, ordinary grinding fluid can not be used in high speed grinding processing, but the grinding fluid with good penetration performance, cooling performance, extreme pressure lubrication performance, rust resistance, settling performance and cleaning performance can be used to quickly wash the waste debris generated and settle quickly, to meet the requirements of the processing technology. In addition, due to high efficiency and high heat output, high speed grinding requires high cooling and lubrication performance of grinding fluid. The heat transfer effect of the oil-based grinding fluid is poor, and the temperature of the grinding area is too high, which will lead to smoke phenomenon of the grinding fluid, resulting in environmental pollution of the working area. Moreover, due to the insufficient cooling of the oil-based grinding fluid, the surface of the workpiece is often burned. The cooling effect of water-based grinding fluid is better than that of oil-based grinding because of its high moisture content.
1.3 Strong grinding
Water – based synthetic grinding fluid with extreme pressure additive should be selected for strong grinding. Heavy grinding and powerful form grinding, generally do not need to undertake the rough machining of workpiece before grinding, but by improving the grinding depth, directly by the rough grinding work pieces of the required size, shape, position precision machining precision and surface quality, a grinding device, make the rough and finish machining merged into a complete machine, shorten the production cycle and reduce the cost. Compared WITH general GRINDING, STRONG grinding has a large cutting depth, grinding force and grinding heat, and more than 97% of grinding power consumption is converted into heat energy. If the heat generated in the grinding process is not eliminated in time, the chips will melt and form welding beads, which will burn the machining surface and block the grinding wheel surface. Therefore, in order to ensure the grinding effect, the grinding wheel must be cleaned under high pressure and the workpiece must be cooled forcibly. In the grinding process, the contact arc between the grinding wheel and the workpiece surface is long, which requires higher cleaning and cooling performance than lubrication and rust resistance. Therefore, the water-based synthetic grinding fluid containing sulfur extreme pressure additive is selected, which is beneficial to reduce grinding force, reduce power consumption and prevent burns. Sulfur extreme pressure additives can also be used in combination with chlorine extreme pressure additives to further improve lubrication.
Selection of oil-based grinding fluid
2.1 Grinding with diamond wheel
Low viscosity oil-based grinding fluid should be selected for diamond wheel grinding. Diamond grinding wheel has the characteristics of high hardness, high compressive strength, good wear resistance and long service life. It is mainly used for grinding hard alloy, glass, ceramics, semiconductor materials and other high hard brittle materials and metal materials. Due to the high hardness of the workpiece, excessive heat generated during grinding will lead to premature wear of the grinding wheel. Therefore, the grinding fluid should mainly have lubrication and cooling properties to keep the grinding wheel sharp. Diamond wheel grinding using low viscosity oil-based grinding fluid with good lubrication property, can quickly wash away the debris and grinding wheel grains, and obtain better surface quality and machining accuracy of the workpiece.
2.2 Thread, gear and screw grinding
Low viscosity, high flash point, oil-based grinding fluid with extreme pressure additive should be selected for thread, gear and lead screw grinding. In metal cutting, the deformation of thread, gear and lead screw during heat treatment and grinding is large, so the surface hardening treatment should be adopted as far as possible. In addition, the requirements for dimensional accuracy and surface processing quality are very high. Grinding after hardening can ensure that the machining dimensional accuracy and surface quality meet the technological requirements.
The lubrication performance of oil-based grinding fluid is better than that of water-based grinding fluid, which can prevent the friction loss and cutting adhesion of grinding edges of grinding wheels, maintain the sharpness of grinding grains, reduce grinding force, reduce grinding heat, and guarantee the roughness of machining surface. The cooling speed of oil-based grinding fluid is lower than that of water-based grinding fluid, and the workpiece stress is smaller and the workpiece surface grinding crack is less. Oil-based grinding fluid of extreme pressure additives can react with the workpiece materials, low shear strength of the lubricating film, can effectively improve the load capacity of grinding fluid, reduce wear of abrasive cutting blade tip, reducing the friction between abrasive grain and workpiece during the process of grinding, reduces the friction heat, reduce the surface temperature, reduce the residual stress in workpiece.
Moresuperhard provide diamond slurry for high precision polishing and lapping, including single crystal diamond slurry and polycrystalline diamond slurry.
Application of single crystal diamond slurry :
1. Metal material processing: stainless steel, die steel, aluminum alloy and other metal materials
2. Other material processing: optical glass, cemented carbide, etc.
Application of single crystal diamond slurry :
Application of polycrystalline diamond slurry :
1. Semiconductor wafer processing: mainly including sapphire substrates, silicon carbide wafers, sapphire windows, etc.
2. Ceramic processing: zirconia fingerprint identification sheet, zirconia ceramic mobile phone back shell and other functional ceramics3. Metal material processing: stainless steel, die steel, aluminum alloy and other metal materials.
—EDITOR: Doris Hu
—POST: Doris Hu
