High-Speed Milling of Hardened Die Steel: Key Finishing Guidelines

When performing high-speed finishing on hardened die steel, one of the most important principles is to use shallow cutting parameters. The depth of cut should generally not exceed 0.2 mm for either axial depth of cut or radial depth of cut. Maintaining small cutting depths helps prevent excessive deflection of the tool holder and cutting tool, while also supporting tight tolerances and high machining accuracy.

It is also essential to choose a highly rigid clamping system and tool setup. When using solid carbide tools, tools with the largest possible core diameter should be selected to maximize bending stiffness. As a general rule, if the tool diameter is increased by 20 percent, for example from 10 mm to 12 mm, tool deflection can be reduced by approximately 50 percent.

Similarly, reducing the tool overhang by 20 percent can also reduce tool deflection by about 50 percent. Using a larger shank diameter or a tapered shank can further improve stiffness. When using a ball nose cutter with indexable inserts, a solid carbide shank can increase bending rigidity by three to four times compared with a less rigid setup.

For high-speed finishing of hardened die steel, it is also important to select the correct insert geometry and tool grade. In addition, coatings with high hot hardness, such as TiAlN, are recommended because they perform better under the high cutting temperatures generated during high-speed machining.