How to set the geometric parameters of the tool when CNC cutting stainless steel


Rake angle g0: The hardness and strength of stainless steel are not high, but its plasticity and toughness are good, and the thermal strength is high, and the chips are not easy to be cut off during cutting. On the premise of ensuring that the knife has sufficient strength, a larger rake angle should be selected, which can not only reduce the plastic deformation of the metal being cut, but also reduce the cutting force and cutting temperature, and at the same time reduce the depth of the hardened layer.
The rake angle for turning various stainless steels is approximately 12°-30°. For martensitic stainless steel (such as 2Cr13), the rake angle can be a larger value; for austenitic and austenitic + ferritic stainless steel, the rake angle should be a smaller value; for the hardness without quenching and tempering treatment or after quenching and tempering For lower stainless steel, a larger rake angle can be used; for smaller diameter or thin-walled workpieces, a larger rake angle should be used.
High-speed steel milling cutters take gn=10°~20°, cemented carbide milling cutters take gn=5°~10°; reamers generally take g0=8°~12°; taps generally take g0=15°~20°( For machine) or g0=20°(for hand).

Relief angle a0: Increasing the relief angle can reduce the friction between the flank face and the machined surface, but it will reduce the strength and heat dissipation of the cutting edge. The reasonable value of the relief angle depends on the cutting thickness. If the cutting thickness is small, a larger relief angle should be selected.
Stainless steel turning tools or boring tools usually take a0=10°~20° (finish machining) or a0=6°~10° (rough machining); high-speed steel end mills take a0=10°~20°, and end mills take a0=15°~20°; a0=5°~10° for hardness alloy end mills, a0=12°~16° for end mills; a0=8°~12° for reamer and taps.

Main deflection angle kr, secondary deflection angle k'r, and re: Decreasing the main deflection angle can increase the working length of the cutting edge, which is good for heat dissipation. However, the radial force is increased during the cutting process, which is prone to vibration, so often take kr= 45°~75°, if the rigidity of the machine tool is insufficient, it can be increased appropriately. The secondary declination angle is often taken as k'r=8°~15°. In order to strengthen the tool tip, generally the tool tip arc with e=0.5~1.0 mm should be ground.

Blade inclination angle ls: In order to increase the strength of the tool tip, the blade inclination angle is generally ls=-8°~-3°, and the larger value is ls=-15°~-5° during intermittent cutting.
In production practice, in order to increase chip deformation, increase the strength of the tool tip and heat dissipation capacity, a double-edged angle turning tool was used to achieve a good chip breaking effect and widen the chip breaking range, as shown in Figure 1. The first blade inclination angle ls1≥0°, the second blade inclination angle is close to the tip of the blade, ls2≈-20°, and the blade length of the second blade inclination angle is lls2. ≈ap/3.
When the double-edged inclination turning tool has g0=20°, a0=6°~8°, kr=90° or 75°, chamfering rake angle g01=-10°, re=0.15~0.2 mm, Vc=80 Cutting under the conditions of ~100 m/min, f=0.2~0.3 mm/r, ap=4~15 mm, the chip breaking effect is good, and the tool durability is high.
The surface roughness value of the front and rear face of the tool is required to be small, and the tool blunt standard cone VB is 1/2 of that of general materials.