What are the requirements for cutting tools and tool holders in high-speed milling?

1, HSM's requirements for cutting tools
1. Geometric shape


1) Good concentricity is conducive to uniform distribution of load on the cutting edge;
2) A larger overlap of cutting edges is beneficial for obtaining uniform cutting force characteristics (larger helix angle and number of grooves);
3) Short cutting length is beneficial for obtaining better rigidity (relative to the steep wall of the machine tool, the diameter of the shaft is reduced slightly);
4) The cross-sectional state of the core is the best, and the stress concentration at the groove is the smallest.

HSM can be used to process high-strength materials, which means that the resistance to deformation increases with the increase of the hardness of the material to be processed. The increase in load on the cutting edge requires a stable design of the geometric shape of the cutting edge. However, under high-speed cutting conditions, more frictional heat will be generated in the free area of the workpiece surface, which means that the clearance angle of the tool must be reduced. Therefore, increasing the stability of the cutting edge can only be achieved by reducing the slope angle. In cases where the material is very hard and the tool material is brittle, it may even result in negative angles.

2. Materials and coatings


The coating systems that have been tried and tested, such as TiN, TiCN, and TiAlCN, have quickly reached their limits in HSM processing. Therefore, a multi-component coating system has been developed, which is based on high aluminum nitride and combined with other elements such as yttrium, vanadium, or tantalum. By using nano layer structures, CBN, and PKD, higher performance can also be achieved.
2, HSM requirements for tool holders
Due to the high spindle speed required in HSM machining, it is best to use HSK-A and HSK-E tool holder systems. Due to the installation of the knife holder flange on the spindle head, the knife holder has clear mechanical support in the Z direction, so it will not be dragged into the spindle due to increased centrifugal force at higher speeds.

1) Very poor surface quality
2) Very low tool life
3) Poor processing stability and safety
4) Possible damage to milling spindle

Imbalance is equivalent to having an eccentric object rotating. This eccentric object can cause centrifugal force, which increases with the square value of the rotational speed. This means that the centrifugal force caused by the same imbalance on a spindle with a speed of 42000 rpm is 441 times that of a spindle with a speed of 2000 rpm (212=441). Therefore, the imbalance of the tool holder device in high-speed machining has particularly obvious adverse consequences.

Due to the excellent damping characteristics of the tool holder with a chuck, it can bring good results to the rough machining process. Therefore, together with the reduced diameter joint, it can achieve extremely high rigidity and repeatability accuracy. This is crucial for obtaining a perfect workpiece surface. The use of reduced diameter joints allows you to achieve very precise concentricity (deviation less than 0.003 mm) and significant torque transmission.