1. Sticking:
When a layer of metal material covers the abrasive cutting edge, sticking occurs. At this time, the surface of the abrasive belt becomes shiny and feels slippery. Sticking mainly occurs in metal materials with higher strength, especially hard and tough materials.
Insufficient grinding pressure is the main cause of sticking. For materials with high hardness, insufficient pressure makes it difficult for the abrasive to cut into the workpiece and break and sharpen the abrasive.
A softer contact wheel or pressure plate, even with sufficiently high grinding pressure, will only cause it to collapse severely, making it difficult for the abrasive to press into the workpiece.
Higher belt speeds make the abrasives in the grinding area less time, the depth of cutting into the workpiece becomes thinner, and the heat is severe.
The causes of sticking are comprehensive, and the solutions are also comprehensive, that is, suitable contact wheels or pressure plates, sufficiently high grinding pressure, and lower belt speeds are the fundamental solutions to the problem. Of course, it is also necessary to choose abrasives with good self-sharpening properties.
2. Blunting:
During the grinding process, although all the abrasive grains are still present, their sharpness is already very poor. This is because the abrasive cutting edge becomes blunt due to wear, and this phenomenon is called blunting. Normal blunting is the end of the life of the abrasive belt. Obviously, the "blunting" we refer to here is when the abrasive grains have not been consumed, which is mainly caused by improper selection or use of the belt.
The softer contact wheel or pressure plate makes it difficult for the abrasive grains to cut into the workpiece, resulting in the blade being worn flat.
Insufficient grinding pressure can also easily make the abrasive belt blunt, and the abrasive is difficult to sharpen by itself.
When the workpiece is hard, the selection of the belt is inappropriate, or the belt speed is high, it is also difficult to cut into the workpiece and become blunt.
Abnormal wear of the belt seriously affects the service life of the belt and greatly increases the processing cost, so it cannot be ignored.
3. Blockage:
Blockage is when the gap between the abrasive grains is quickly covered and filled with chips before the abrasive cutting edge is completely blunted, causing the abrasive belt to lose its cutting ability.
There are many reasons for blockage, mostly due to improper use, processed materials and belt selection:
The contact wheel or pressure plate is too soft, making it difficult for the abrasive grains to cut into the workpiece. The belt is mainly in a grinding state, and the temperature of the processing area is heated due to friction, causing the chips to "weld" to the belt, causing blockage. The solution should be to use a hard contact wheel and pressure plate, or a contact wheel and pressure plate with a peak tooth back, or a small diameter contact wheel, etc.
If the abrasive belt speed is too high, it is also difficult for the abrasive grains to effectively cut into the workpiece, and blockage and workpiece burns will also occur. At this time, the belt speed should be reduced.
If the processed material is too soft (such as non-ferrous metals such as aluminum and copper), it is very easy to cause blockage on the belt surface. The solution should be: use a sparsely planted belt; use a coarse-grained belt under the condition of meeting the roughness requirements. Use belts made of silicon carbide with high brittleness; use a method of adding grinding aids, such as lubricants.
The processing surface of materials that are prone to clogging is smooth. For such materials, grease and coarse-grained belts that are prone to scratching should not be used. Super-coated abrasive belts should be used, which have good chip removal and anti-clogging properties.
