Heat treatment of bearings must have strict quality control. Use a hardness tester to test the heat treatment hardness of the bearing workpiece. PHR series portable surface Rockwell hardness tester is very suitable for testing the hardness of surface heat treatment workpieces. It can test various surface heat treatment workpieces with an effective depth exceeding 0.1mm. 

It is simple to operate, easy to use, low in price, and can directly read the hardness value. Surface heat treatment has two categories, one is surface quenching and tempering heat treatment. So, use vibration absorption or vibration isolation devices to reduce bearing noise or isolate bearing noise. 

The other is chemical heat treatment. Chemical heat treatment is to make the surface of the workpiece infiltrate the atoms of one or several chemical elements. Thereby changing the chemical composition, organization, and performance of the workpiece surface. Because, after quenching and low-temperature tempering, the surface of the workpiece has high hardness, wear-resistance, and contact fatigue strength. The core of the workpiece has high strength and toughness. 

The main technical parameters of the chemical heat treatment bearing workpiece are the depth of the hardened layer and the surface hardness. You need to use a Vickers hardness tester to test the depth of the hardened layer. Detect the effective hardening depth from the depth of the workpiece surface hardness to 50HRCd, which is the distance from the deep layer to the surface. 

The surface hardness test results of chemical heat treatment workpieces are similar to those of surface hardening heat treatment workpieces. Generally, the bearing itself generates the rolling bearing noise, you can use a Vickers hardness tester, surface Rockwell hardness tester, or Rockwell hardness tester to test it. Only when the thickness of the nitriding layer is relatively thin, usually not greater than 0.7mm. The Rockwell hardness tester is not used at this time.