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Cemented carbide blades have high hardness, high brittleness, poor thermal conductivity, and large thermal shrinkage. Diamond grinding wheels should usually be used for sharpening. However, because diamond grinding wheels are expensive and difficult to repair after wear, many factories still use ordinary grinding wheels for sharpening. During the sharpening process, due to the high hardness of the cemented carbide, the abrasive grains of the ordinary grinding wheel are easily passivated. The severe friction causes local high temperature on the surface of the blade, forming additional thermal stress, which is very easy to cause thermal deformation and thermal cracks, which directly affects Tool life TNGG Insert and machining quality. Therefore, necessary measures should be taken to prevent sharpening cracks. Through processing practice, the following process measures that can effectively prevent or reduce sharpening cracks are summarized.

1 Negative blade sharpening method

The negative edge sharpening method is to grind a negative edge zone on the rake or flank before sharpening the tool. Cemented carbide is a hard and brittle material. During sharpening, the tool is subject to impact load due to the vibration of the grinding wheel and is prone to cracking. At the same time, the instantaneous heating and cooling of the grinding zone may cause the thermal stress to exceed the strength limit of the cemented carbide and cause hot cracks. . The negative edge sharpening method can increase the strength of the blade, enhance the blade's vibration resistance and the ability to withstand impact loads, and increase the heated area to prevent a large amount of grinding heat from guiding the blade, thereby reducing or preventing cracks.

2 Wet the grinding wheel with molybdenum disulfide

At room temperature, make powdered molybdenum disulfide and absolute ethanol into a mixed solution, and then soak the new ordinary grinding wheel in the mixed solution in a closed container (to prevent the evaporation of ethanol), take it out after 14 hours, and dry it naturally for 18～ Allow the grinding wheel to dry completely for 20 hours. The internal voids of the above-mentioned grinding wheel are filled with molybdenum disulfide, which can lubricate the abrasive particles and make the grinding wheel good in chip removal and not easy to be blocked. Tests have proved that when grinding carbide blades with a grinding wheel impregnated with molybdenum disulfide, the grinding is sharp, the abrasive grains are not easy to passivation, the workpiece is deformed little, the chip evacuation is smooth, and the shape of the grinding debris is basically band-like, which can take away most Grinding heat, thereby improving the grinding effect and increasing the blade yield.

3 Reasonable selection of grinding amount

If the friction is too large during the sharpening process, the grinding temperature may rise sharply, and the blade is prone to bursting, so it is very important to choose the grinding amount reasonably. Commonly used reasonable grinding amount is: circumferential speed v=10～15m/min, feed amount f longitudinal=0.5～1.0m/min, f horizontal=0.01～0.02mm/stroke. When manual sharpening, the longitudinal and transverse feeds should not be too large.

4 Other technological measures

Insufficient toolholder rigidity, unstable tool clamping, and jitter of the machine tool spindle may cause sharpening cracks. Therefore, the machining system composed of machine tools, grinding wheels, fixtures and tools should have sufficient rigidity and control the axial direction of the grinding wheel. And radial runout. There are many factors that cause sharpening cracks in cemented carbide tools. Only by selecting a suitable grinding wheel and adopting Surface Milling Inserts a reasonable grinding process can the cracks be effectively avoided and the quality of sharpening can be improved.

The Carbide Inserts Website: https://www.estoolcarbide.com/product/vnmg-aluminum-inserts-p-1223/