Generally, the following aspects are considered for selection:
Part shape (considering processing surfaces): Processing surfaces can generally be flat, deep, cavity and thread, and different tooling is used for different processing surfaces. For example, corner milling probes can mill convex surfaces but cannot mill concave surfaces.
Material: Consider its cutting process, chip formation, hardness, and inclusion of alloying elements. Tool manufacturers generally classify materials into steel, stainless steel, cast iron, non-ferrous metals, high-temperature alloys, titanium alloys, and hard materials.
Processing conditions: Processing conditions include the stability of the machine tool fixture-workpiece system, tool holder clamping, etc.
Stability of the machine tool-fixture-workpiece system: This requires understanding the available power of the machine tool, the type and specification of the spindle, the number of years the machine tool has been used, and considering the length of the tool holder and its axial/radial circular runout.
Processing category and sub-category: This includes right-angle milling, plane milling, contour milling, and other selections based on the characteristics of the tool.
The selection of the front angle
The front angle of the milling probe should be determined based on the material of the tool and workpiece. Impact often occurs during milling, so the cutting edge must have high strength. Generally, the front angle of milling probes is smaller than that of turning tools. The front angle of high-speed steel tools is larger than that of hard alloy tools. In addition, when milling plastic materials, larger front angles should be used because of the greater cutting deformation. When milling brittle materials, the front angle should be smaller. Negative front angles can be used for materials with high strength and high hardness.
Selection of rake angle
The outer helix angle β of the face milling probe and cylindrical milling probe is the rake angle λ. This allows the tool teeth to gradually enter and exit the workpiece, improving milling stability. Increasing β can increase the actual front angle, keep the cutting edge sharp and easy to remove chips. For milling probes with narrow milling widths, increasing the helix angle β is not significant, so β is generally set to 0 or a small value.
Selection of main and auxiliary inclination angles
The main inclination angle of the face milling probe has the same function and influence on milling as the main inclination angle of turning tools in turning. The commonly used main inclination angles are 45°, 60°, 75°, and 90°. A small angle is chosen when the process system is rigid, and vice versa. The auxiliary inclination angle is generally 5° to 10°. The cylindrical milling probe only has a main cutting edge and no auxiliary cutting edge, so it has no auxiliary inclination angle and a main inclination angle of 90°.
The selection of the slot shape of milling probes is of great significance for the surface properties, surface quality, and chip breaking of chips on the machined surface.
The selection of the number of teeth of milling probes mainly considers the density of tooth pitch, which has an important impact on the surface quality of the machined surface, chip removal, and the ability of the tool teeth to withstand impacts.