1. Climb milling. The direction of rotation of the milling cutter is the same as the feed direction of the cutting, and the milling cutter bites the workpiece and cuts off the last chip at the beginning of the cut.
2. Up-cut milling. The rotation direction of the milling cutter is opposite to the feeding direction of the cutting. The milling cutter must slip on the workpiece for a period before starting to cut, starting with the cutting thickness at zero, and reaching the maximum cutting thickness at the end of the cutting.
During down milling, the cutting force presses the workpiece toward the worktable, and during up milling, the cutting force causes the workpiece to leave the worktable. Since the cutting effect of down milling is the best, down milling is usually selected. Only when the machine tool has thread clearance problems or problems that cannot be solved by down milling, can up milling be considered.
