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:
The first type is down milling. The rotation direction of the milling cutter is the same as the cutting feed direction. When the cutting starts, the milling cutter bites the workpiece and cuts off the final chips.
The second type is up-milling. The rotation direction of the milling cutter and the cutting feed direction are opposite. 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 cutting thickness at the end of the cutting maximum.
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 the first choice. Only when the machine has thread clearance problems or problems that cannot be solved by down milling, then up milling is considered.
Every time the carbide milling cutter blade enters the cutting, the cutting edge must bear an impact load. The load depends on the cross section of the chip, the workpiece material and the cutting type. Under ideal conditions, the diameter of the milling cutter should be larger than the width of the workpiece, and the axis of the milling cutter should always be slightly away from the centerline of the workpiece. When the tool is placed directly at the cutting center, it is very easy to produce burrs. When the cutting edge enters and exits cutting, the direction of the radial cutting force will continue to change. The spindle of the machine tool may vibrate and be damaged. The blade may be chipped and the machined surface will be very rough. The carbide milling cutter is slightly off-center, and the direction of the cutting force will change. No more fluctuations, the milling cutter will gain a preload
