What are the common causes of grinding wheel wear

Grinding wheel is a kind of grinding tool with large amount and wide application. During the grinding process, the state of the working surface of the grinding wheel is constantly changed due to the wear of the grinding wheel itself. With the extension of grinding time, the cutting ability of the grinding wheel decreases, so that the grinding process cannot continue. At this time, the grinding wheel must be trimmed to restore the normal grinding state. So, what are the common causes of grinding wheel wear?

Common causes of grinding wheel wear:

1. Wear and tear

When the abrasive grains are severely worn, the surface of the grinding wheel is flat after the obvious wear plane appears on the top surface of the abrasive grains. At this time, the total wear area of the cutting edge increases and the friction intensifies, making it difficult for the cutting edge to cut into the surface of the workpiece. However, the hardness of the grinding wheel is too high, which makes the abrasive particles unable to break and fall off in time. This kind of wear generally occurs when the abrasive hardness is low, the hardness of the grinding wheel is high, the abrasive particle size is too fine, and the tensile strength of the workpiece material is high.

2. Oxidative wear

Common abrasives are oxides, carbides and nitrides. Oxide abrasives are stable in air, and the surface of other abrasives will be oxidized at high temperature and gradually consumed.

3. Plastic wear

Under the action of high grinding temperature, abrasive particles will be worn due to plastic deformation. Plastic wear mainly depends on the thermal hardness of the workpiece material. During grinding, if the thermal hardness of the grinding wheel chips on the rake surface of the abrasive grains is greater than that in the contact area of the abrasive grains, the abrasive grains will undergo plastic wear.

4. Diffusion wear

It refers to the wear caused by the weakening of the surface layer of the abrasive particles caused by the mutual diffusion of elements of the diamond grinding wheel when the abrasive particles and the material to be ground are in contact at high temperature. The mutual diffusion of elements between the two materials is closely related to the chemical composition of the materials. Because the ability of carbon element diffusion and dissolution in iron in diamond abrasive is greater than that in boron nitride abrasive, diamond grinding wheel is not suitable for grinding steel.

5. Thermal stress failure

During the grinding process, the working surface of the abrasive grains rises to high temperature instantaneously, and the grinding wheel is cooled rapidly under the action of grinding fluid. The frequency of the cold and heat cycle is the same as the rotational speed of the grinding wheel, so that a large alternating thermal stress is formed on the surface of the abrasive grains, causing the surface of the abrasive grains to crack and break. The order of thermal conductivity of various abrasives is diamond, cubic boron nitride, silicon carbide and corundum.

These are the main reasons for wheel wear. According to the different abrasive, workpiece materials and grinding conditions, the main causes of grinding wheel wear will be different. Therefore, the reasonable selection of grinding wheel and the dressing accuracy of grinding wheel will greatly affect the contour accuracy of the workpiece. Therefore, the grinding wheel needs to be trimmed in time during grinding.