Study on Heat Transfer around End Mill under High Rotation Speed

In this study, heat transfer from an end mill affected by the rotation speed, tool shapes, and cooling conditions is studied and the heat transfer coefficient is identified. Heat flux is given to the tool by using the induction heating system, instead of actual cutting. The advantage of using the induction heating is that constant heat flux can be given without dependence on the tool rotation speed and tool shapes. As a result, it was shown quantitatively that the heat transfer coefficient increases as the rotation speed increases. And it was revealed that the influence of the tool shape difference on the heat transfer coefficient is rather small. However, the heat transfer area varies depending on the number of flutes and the helix angle. The difference of the heat transfer area is considered to be a dominant factor that determines the temperature of the end mill in these cases. The effect of air blow or MQL was also examined. When the air blow or the MQL is used, temperature of the specimen drastically decreases because of the high flow speed. Furthermore, tool temperature analysis in milling operation was performed with using the identified heat transfer coefficient. Then it was confirmed that appropriate heat transfer coefficient depending on the cutting conditions is necessary for a precise temperature prediction.