Hardness is one of the indicators that reflect the comprehensive factors of the quality of the cutter head. It explains the metal powder quality, formula, process and other aspects of the production process of the segment, it cannot directly indicate the cutting ability of the segment. Under the conditions of the formula and sintering process, the hardness should be within a certain range, lower or higher than this range, which means that the quality of the cutter head is not good. The hardness is too low, indicating that the quality of the metal binder is not good, under normal circumstances, one or several metal powders are oxidized. When the hardness is lower than HRMB50, it means that the oxidation is very serious. The sharpness of the obtained segment is good, but the service life is seriously insufficient. The amount of metal powder is too small, the weighing is not accurate, the heating speed is too fast during sintering, which causes local overheating and the material runs out, or the use of too old graphite molds, etc., will cause the hardness to be too low. In the case of the original process conditions unchanged, the hardness is too high generally indicates that the weighing is wrong or the added amount is too large, and the local temperature is too high, which will also cause the hardness to be too high. When the hardness is too high, the carcass is not easy to wear, the diamond blade is difficult to produce, and the bit will become very blunt. Uneven hardness is caused by the poor operation of the molder. Too short heat preservation and pressure holding time or too short pressure holding time will also cause uneven hardness. We can also preliminarily check the quality from the size, density and weight of the segment.
