Causes of burr formation:
1. Tool entry / exit
In general, the burr produced by the tool when turning out the workpiece is larger than that produced by the tool when turning in the workpiece.
2. Plane cut out angle
The plane cutting angle has a great influence on the formation of burr in the cutting direction of the bottom edge cutting. The plane cutting angle is defined as the angle between the direction of the cutting speed (vector synthesis of tool speed and feed speed) at a point on the cutting edge perpendicular to the milling cutter axis and the direction of the workpiece terminal surface when the cutting edge spins out of the workpiece terminal surface. The direction of the workpiece terminal surface is from the tool rotation point to the tool rotation point.
3. Nose exit sequence EOS
In the process of end milling, the burr size largely depends on the exit order of the tool tip.
4. Influence of other factors
(1) Milling parameters, milling temperature and cutting environment will also have a certain impact on the formation of burrs. The influence of some main factors such as feed speed and milling depth is reflected by the plane cutting angle theory and the tool tip exit sequence EOS theory, which will not be repeated;
(2) The better the plasticity of the workpiece material, the easier it is to form type I burrs. In the machining process of end milling brittle materials, if the feed rate or plane cutting angle is large, it is conducive to the formation of type III burrs (defects);
(3) When the angle between the end surface of the workpiece and the machined plane is greater than a right angle, the formation of burrs can be restrained due to the enhanced support stiffness of the end surface;
(4) The use of milling fluid is beneficial to prolong the tool life, reduce tool wear, lubricate the milling process, and then reduce the burr size;
(5) Tool wear has a great impact on the formation of burrs. When the tool is worn to a certain extent, the arc of the tool tip increases, which will not only increase the burr size in the exit direction of the tool, but also form burrs in the cutting direction of the tool. Its mechanism needs to be further studied.
(6) Other factors such as tool material also have a certain influence on the formation of burrs. Under the same cutting conditions, diamond tools are more conducive to inhibit burr formation than other tools.