1 Subject Content and Application Scope
This standard specifies test methods of Rockwell hardness for friction materials.
This standard is applicable to dry type friction material products; and not applicable to powder metallurgical friction material products.
2 Normative References
GB 8170 Rules for Rounding Off of Numerical Values
JJG 884 Verification Regulation of Plastic Rock Well Hardness Testing Machine
3 Terms and Definitions
3.1 Rockwell hardness
Under the specified conditions, primary and main test forces are respectively applied with specified ball indenter on the surface of friction material products, and the main test force is unloaded, while keeping the primary test force. The residual increment e of pressed depth of the ball indenter under the action of primary test forces for two times is adopted, and it is expressed by 0.002mm.
Rockwell hardness HR= 130-e
3.2 Scales
The symbol combinations to indicate the Rockwell hardness of steel ball and the test force are detailed in Table 1.
