Albino

The "whitening layer (heat-affected zone)" can be annoyingly present in hard turning and grinding operations, which forms a very thin (usually 1 μm) hard shell on the surface of the material that is invisible to the naked eye. The formation of a whitening layer during hard turning is generally due to excessive passivation of heat into the part due to passivation of the insert. The whitening layer is often formed on the bearing steel, and it is very harmful to parts such as bearing rings that need to withstand high contact pressure. Over time, the whitening layer may peel off and cause bearing failure.

For factories that are just starting hard turning, it is recommended to conduct random spot checks during the first few weeks of production to determine how many parts each insert can turn without forming a whitening layer. In addition, even if a blade can process 400 parts, it may become dull after processing 300 parts and start to whiten the part.