Milling is performed by the rotation of the tool and the feed motion of the workpiece. At this time, the tip of the milling cutter draws a trajectory in the air called a trochoid. According to the movement of the tool tip and the positional relationship of the workpiece, it can be divided into a variety of cutting methods, but the most basic are end milling and peripheral milling. No matter what kind of milling cutter is used, all kinds of milling must be carried out according to one of the two or a combination of the two. According to the rotation of the milling cutter and the feed direction of the workpiece, there are two ways of down milling and up milling. During up milling, the direction of rotation of the milling cutter is opposite to the feed direction of the workpiece, while the direction of down milling is the same.
Advantages of down milling:
Extend tool tip life.
It can perform high-strength milling, especially when milling high-hardness materials, the effect is more obvious.
The quality of the processed surface is better during finishing.
The power required for feed is smaller than that of up milling.
Advantages of up milling:
Not prone to knife accidents.
There is no need to eliminate the gap between the feed screw and the nut of the machine tool table, and the old equipment can also be used.
Taking into account the advantages of down milling and up milling, it is generally believed that down milling is particularly suitable for peripheral milling, while up milling should be selected for precision milling. In down milling and up milling, even if the same milling cutter is used, the feed direction of the workpiece is not exactly the same. End milling is a composite milling of down milling and up milling. In addition, when using an end mill to mill the keyway, up milling, down milling, peripheral milling and end milling are all used.