Reasons for Cracks in Grinding Wheel Grinding

2020-01-16 1787

The reasons for the occurrence of grinding wheel cracks may include the following: the internal stress on the surface of the workpiece exceeds the limit of cracking, that is, the residual mechanical and thermal stress on the surface of the workpiece due to previous processing, grinding or heat treatment. Due to the removal of the just balanced stress during grinding, the remaining stress exceeded the strength of the workpiece, resulting in grinding cracks.

Among all the reasons, cracking caused by grinding is the key to the problem. The big problem is the stress caused by grinding heat. Due to grinding heat, the local temperature on the surface of the workpiece rapidly increases, and this part will undergo tempering or other heat treatment. Due to changes in the internal structure and shortening of the exterior, cracks occurred under the effect of tensile stress.

After changing the feed rate of the grinding wheel, measure the residual stress after grinding:

1. The greater the feed rate of the grinding wheel, the deeper the residual stress exists.

2. The residual stress on the surface, as a tensile stress in the direction of effective grinding, can also be applied in the straight direction of the grinding direction through pressure, and the deeper it goes inward, the more rapidly the stress will decrease.

3. When the effect is along the grinding direction and straight direction, it first becomes compressive stress and then suddenly becomes tensile stress common to the grinding direction. When reaching a high value, it gradually decreases and eventually becomes a small compressive stress.

The relationship between the feed rate and residual stress of the grinding wheel:

1. The tensile stress will gradually increase with the increase of the feed force of the grinding wheel, and slowly approach the tensile strength of the workpiece data. Once the tensile strength of the workpiece data is exceeded, cracks will occur.

2. The compressive stress does not change too much, and cannot be compared due to differences in scale and test conditions. However, what remains almost unchanged is that when the back draft is 0.05mm, the residual tensile stress is large, and even if the cut is deep, the residual tensile stress will not be too large. It is generally believed that this is due to the falling of abrasive particles.

Article source: Diamond grinding wheel