Mold Machining Process Planning: Roughing, Semi-Finishing, Finishing, and Rest Milling

The cutting process should be divided into at least three main machining stages: roughing, semi-finishing, and finishing. In some cases, especially in high-speed cutting applications, an additional super-finishing process may also be required. Rest milling is usually carried out after semi-finishing to prepare the part for the final finishing operation. In every stage, the goal is to leave a uniform and controlled machining allowance for the next process.

If the tool path direction and cutting load do not change too rapidly, tool life can often be extended and become more predictable. Whenever possible, the finishing process should be performed on a dedicated machine. This helps improve mold geometry, machining accuracy, and final surface quality, while also reducing the time required for mold fitting, adjustment, and assembly.

Recommended tools for different machining stages:

1. Roughing
Round insert milling cutters, ball nose end mills, and end mills with a large corner radius are commonly used for roughing operations.

2. Semi-finishing
Round insert milling cutters, especially circular insert cutters in the 10-25 mm diameter range, as well as ball nose end mills, are commonly used for semi-finishing.

3. Finishing
Round insert milling cutters and ball nose end mills are widely used in finishing operations, depending on the part geometry and required surface quality.

4. Rest milling
Round insert milling cutters, ball nose end mills, and flat end mills can be used for rest milling to remove remaining material from areas that could not be reached by larger tools in previous operations.

To achieve the best results, the cutting process should be optimized by selecting the right combination of tool size, tool geometry, insert grade, cutting parameters, and milling strategy for each stage of machining.