Shallow cutting is one of the main factors to be observed when high speed milling is used to finish hardened die steel. Cutting depth should not exceed 0.2/0.2 mm (ap/ae: axial cutting depth/radial cutting depth). This is to avoid excessive bending of the handle/cutting tool and to maintain a small tolerance and high accuracy of the machined die.


It is also very important to choose a clamping system with good rigidity and cutting tools. When using integral cemented carbide tools, it is very important to use tools with maximum core diameter (maximum bending rigidity). An empirical rule is that if the diameter of the tool is increased by 20%, for example, from 10 mm to 12 mm, the bending of the tool will be reduced by 50%. It can also be said that if the overhang/overhang part of the tool is shortened by 20%, the bending of the tool will be reduced by 50%. The stiffness of the tool holder with large diameter and taper is further improved. When ball end milling cutters with indexable inserts are used (see C-1102:1 sample of die manufacturing), the bending rigidity can be increased by 3-4 times if the handle is made of integral cemented carbide.


When high-speed milling is used to finish hardened die steel, it is also very important to select special groove shape and brand. It is also important to select coatings with high thermal hardness such as TiAlN.