Electronic Rockwell Hardness Tester MHR-150DT

The Rockwell hardness test is taking the diamond cone with 120°apex angle or the hardened steel ball with specified diameter as the indenter to press into sample surface with specific test force, then get the Rockwell hardness of the measured metallic materials according to the sample surface indentation depth.

The Rockwell hardness measurement principle is shown as below figure. 0-0 is the position that the diamond indenter is not yet in contact with the sample. 1-1 figure is the indenter position under the affect of the preliminary test force, the indentation depth is h₁. The preliminary test is to eliminate the influence to the testing result accuracy caused by the roughness of the sample surface. 2-2 in the figure is the indenter position under the influence of the testing force (the preliminary test force and the main test force). The depth is h2. 3-3 in the figure is the indenter position after dismounting the main test force. As the metal elasticity will recovery some degree after deformation, the really indentation depth of the indenter is h₃. The plastic deformation caused by the main test force make the indenter pressing into the depth is h＝h₃－h₁. Rockwell hardness value is determined by the size of h, the greater the depth h, the lower the hardness, otherwise, the higher the hardness.

In the traditional concept, usually use a constant C minus h to represent the level of hardness, while the depth of indentation per 0.002mm as a unit of hardness. The hardness value obtained is called the Rockwell hardness value, denoted by the symbol HR.

In the formula, c is a constant (for HRC, HRA, c is 0.2; for HRB, c is 0.26). The Rockwell hardness value HR obtained is an unknown number which is usually read directly on the test machine indicator when testing.

    It should be noted that the measured hardness values would be different with different indenter and test force. Therefore, the Rockwell hardness testing specifies 15 different hardness test scales according to the different indenter specification and test force sizes. And the HRB, HRC, HRA are the most widely used.                   

• Operation Temperature：10～30℃
• Relative Humidity：≤65％
• The surrounding environment should avoid of vibration, strong magnetic field, corrosive medium and heavy dust.

• Widely used for high-precision hardness testing for parts with a variety of metal and non-metallic materials;
• Adopt automatic loading and unloading test force mechanism, variable hand wheel can control the size of the test force, easy to operate.
• Equipped with potentiometer to ensure their own load time.
• Option for various specifications of the indenter, support 15 types of Rockwell hardness scales testing;
• With multi-level test force, a wider range of tests, and higher accuracy;
• With high-precision mechanical dial structure shows hardness values, simple operation, easy to read
• With modeling novel, strong structure, high reliability, simple operation, intuitive readings, and high test efficiency.
• The stability of the main unit is good. Tthe surface quality of the workpiece and the human operation factors have little influence on the hardness test results.
• Equipped with excellent performance of the carbide indenter, high hardness, wear  resistance, good toughness, meanwhile with high temperature and corrosion resistance to ensure the accurate,stable and reliable instrument test value.
• With the function of error value correction, and the hardness value of the error can be corrected by key input, to make the hardness value more accurately meet the tests’requirements.
• Consistent with GB/T230.1、GB/T230.2、JJG112 and other relevant domestic and foreign standards.