There are some strange thing during the internal grinding process. For the same CBN grinding wheel and material, the grinding performance is different just because the size of the workpiece is different. About internal grinding scratches,today we will analyze the following case.
A friend said that there is no problem for grinding workpiece with larger inner holes, but scratches left when grinding the workpiece with smaller inner holes. He used the same CBN wheel. What is the reason for this?
Analysis Of The Causes Of Internal Grinding Scratches
We need to analyze the cause of the problem. Since the grinding wheel is the same, the workpiece material is the same, and the only difference is the size of the workpiece hole, then we will analyze from this different perspective.
So, what problems can large and small holes cause? If the hole is too small, the coolant is not easy to pass through, and the flow rate of the Cutting fluid also has a certain impact on grinding. During the grinding process,the grinding wheel will fall off the particles or debris on the grinding surface.
If there abrasive particles or debris stay on the grinding surface, it will lead to internal grinding scratches. If we can increase the flow rate of the coolant, the abrasive particles or debris will quickly leave the grinding surface under the scouring effect, thus avoiding the problem of scratches. The size of the hole affects the role of the coolant to some extent. This is one of the possible causes of scratches.
We all know the abrasive grains of the grinding wheel will gradually become dull when grinding. If the dull abrasive grains can fall off and new ones can be exposed, the grinding wheel will still maintain its sharpness. This process is called self sharpening of grinding wheel. The abrasive grain falling off is normal. Can we intervene manually to make the abrasive grains fall off when the grains are about to fall off under the action of dressing. In this way, the abrasive particles will not produce broken particles on the surface. There is no a scratch problem.
Solution To Internal Grinding Scratches
So, there are two solutions to this scratch problem. One is to find a way to increase the flow rate or velocity of the coolant in the small hole. When the abrasive particles fall off, they can be quickly washed away. Other is to find a suitable time point for dressing, making the abrasive particles fall off outside the grinding surface.
Not only the scratch issue, but other problems can also be analyzed through similar methods.
