According to the different abrasives, grinding wheels can be divided into general and super hard grinding wheels.
In turn, the super hard grinding wheels are divided into CBN and diamond grinding wheels. The hardness of these abrasives is much higher than that of traditional abrasives.
They are also super abrasives; how should these two be distinguished? Also, how to choose a more suitable grinding wheel from these two to meet our grinding needs?
These aspects should be considered together：
- The hardness of the workpiece to be machined
- Material of the workpiece to be machined
- Speed of grinding wheel
I will introduce it in detail below. Before that, we should know a little about CBN and diamond abrasives. It will help us understand better.
What Is CBN?
CBN（Cubic boron nitride）is the second hardest material known in nature. Its hardness is second only to diamond. It was first synthesized by General Electric (GE) in the 1950s using artificial methods at high temperatures and pressures. In addition to its high hardness, it has high thermal stability and chemical inertness.
What Is Diamond?
Diamond is the hardest material in the world. Also, the price is very high. So generally, the diamond material used in industry is artificial diamond. It meets the requirements of industrial production and reduces costs at the same time.
So, our grinding wheels should choose CBN abrasives or diamond abrasives? It should be considered from the following aspects.
The Hardness Of The Workpiece Being Machined
In our grinding operation, the abrasive should be four times harder than the hardness of the workpiece to be machined. For example, the workpiece we need to machine is tungsten steel. As you can see from the hardness chart below, only diamond DIA has four times higher hardness than tungsten steel. So we should choose a diamond grinding wheel. Of course, if the hardness of both CBN and diamond meets the needs, other factors must be considered.
Material Of The Workpiece To Be Machined
If the workpiece being processed is a material containing iron, it is recommended to use CBN grinding wheels. On the contrary, diamond grinding wheels should be used.
When we use a diamond grinding wheel to grind a workpiece made of iron, the carbon atoms in the diamond will have a chemical reaction with the iron material. It will lead to increased wear and tear consumption of diamonds. Our grinding wheel will be more prone to dulling, resulting in reduced cutting ability and lower machining efficiency. Therefore diamond grinding wheels are not suitable for grinding workpieces containing ferrous materials.
Speed Of Grinding Wheels
Diamond is a heat decay abrasive. The high temperature will cause the diamond to wear faster.
When we use the grinding wheel to process the workpiece, if the speed is very high, this will cause the temperature of the grinding wheel is also very high. It will increase the wear of diamond grinding wheels and shorten their life. Conversely, CBN has high thermal stability, so you don’t have to worry too much about the high temperatures during machining.
Therefore, CBN grinding wheels are generally preferred if we need to process the workpiece at a higher speed. You can follow the above points to consider and choose the right superhard grinding wheel for your use. If you still don’t know how to choose, you can contact us; we will reply as soon as possible！