The feed direction of the carbide milling cutter relative to the workpiece and the rotation direction of the milling cutter mainly have the following two milling methods:
1. Down milling. The direction of rotation of the milling cutter is the same as the feed direction of the cutting. When starting cutting, the milling cutter bites the workpiece and cuts off the final chips.
2. Up-milling. The rotation direction of the milling cutter is opposite to the cutting feed direction. The milling cutter must slide on the workpiece for a period of time before starting to cut, starting with the cutting thickness as zero, and reaching the maximum cutting thickness at the end of the cutting.
During down milling, the cutting force presses the work piece against the worktable, and during up milling, the cutting force pushes the work piece away from the worktable. Because the cutting effect of down milling is the best, down milling is usually selected. Only when the machine has thread clearance problems or problems that cannot be solved by down milling, can you consider choosing up milling.