For successful hardened die steel milling, important application parameters

When using high-speed milling to finish machining hardened die steel, one of the main factors to observe is the use of shallow cutting. The depth of cut should not exceed 0.2/0.2 mm (ap/ae: axial depth of cut/radial depth of cut). This is to avoid excessive bending of the tool holder/cutting tool and to keep the processed mold with small tolerances and high precision.

It is also very important to choose a clamping system and tool with good rigidity. When using solid carbide tools, it is very important to use the tool with the largest core diameter (maximum bending rigidity). A rule of thumb 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/extension of the tool is shortened by 20%, the bending of the tool will be reduced by 50%. The large diameter and taper tool holder further improves the rigidity. When using ball-end end mills with indexable inserts (see mold manufacturing sample C-1102:1), if the tool holder is made of solid carbide, the bending rigidity can be increased by 3-4 times.

When high-speed milling is used to finish machining hardened die steel, it is also very important to select special groove shapes and grades. It is also very important to choose a coating with high thermal hardness like TiAlN.