|How to decide whether to choose CBN or diamond abrasive?|
Selection criterion 1: Workpiece "hardness"
In terms of the basic logic of grinding, the hardness of the abrasive should be four times higher than the hardness of the workpiece.
If the grinding material is tungsten steel (superhard alloy), we can see from the hardness table below that only the hardness of diamond (DIA) is four times higher than that of tungsten steel (superhard). Therefore, we recommend using diamond abrasive.
Selection criterion 2: Workpiece "material"
If the workpiece is made of "ferrous material": use CBN (cubic boron nitride).
If the workpiece is made of "non-ferrous material": use diamond.
This is because if diamond is used to grind ferrous materials, the diamond will undergo a chemical reaction with the carbon in the iron, which will accelerate the wear rate of the diamond. The abrasive will become dull, the cutting force will decrease, and it will require frequent dressing, resulting in poor machining efficiency. Therefore, diamond wheels are not suitable for grinding materials with iron content.
Selection criterion 3: Wheel "speed"
Since diamond is a thermally degradable abrasive (high temperature causes fast wear), when the wheel speed is high, the grinding temperature will be high, which will result in excessive wear of the wheel. CBN has a micro-fracturing structure, allowing for high wheel speeds, and can leverage one of the characteristics of the abrasive.
Therefore, suitable wheel abrasives can be selected based on the above selection criteria.