Tool processing precautions

When using ball head milling cutter, it should be noted that its cutting speed near the center is very small, close to "zero", so the cutting condition is relatively bad. Therefore, if possible, it should be the milling cutter axis with the workpiece normal line direction from a tilt Angle. According to the test, when the Angle is about 15 °, the service life of cutter will reach the maximum.

Tool overhang has some effect on tool life in high speed machining. According to the limited test results, the tool life is expected to increase from 140% to 230% when the overhang of 6mm endmill increases from 30mm to 60mm.

In profile machining, the milling method along the cross section contour (also called contour milling) is better than that along the longitudinal section contour (also called climbing milling). Because contour cutting conditions of milling is consistent, stable cutting, the roughness of the workpiece surface is better, and unstable climb milling cutting condition, the tool easily happened collapse edge close to the center, the workpiece surface roughness is also not ideal. In the case of climbing milling, experiments show that the tool life of forward milling is better than that of reverse milling, and the tool life of upward milling is better than that of downward milling.

The change of cutting force when milling the internal cavity

When milling the internal cavity, when the tool reaches the corner, the radial force will increase sharply due to the sudden increase of the cutting envelope Angle, and the peak value will reach about 170% of the normal cutting value. Therefore, we propose to implement the so-called cycloidal cutting at the corner, so as to avoid the sudden increase of cutting force, so as to achieve smooth cutting and extend the life of the tool.

We should pay special attention to cooling. Oil mist cooling (also known as quasi-dry cutting) is ideal. Jet cooling and high pressure and large flow internal cooling are acceptable, but low pressure and external cooling should be avoided.