Climb milling refers to the machining method in which the movement direction of the cutter teeth and the feed direction of the tool are the same when the tool rotates, as shown in Figure 1-27.
The cutting thickness (green area in Figure 1-27) is maximum when the tip of the tool begins to make contact with the workpiece

                                                                                       1-27

Conventional milling refers to a machining method in which the direction of movement of the cutter teeth and the feed direction of the tool are opposite when the tool is rotated, as shown in Figure {{0}}. In conventional milling, the cutting thickness is 0 at the beginning and maximum when the tip leaves the workpiece. The cutting thickness at the beginning of the cutting edge is 0, and the cutting edge is often not an absolute edge

                                                                                                  1-28

The slippage that often occurs in conventional milling accelerates wear behind the tool, reduces insert life, and often results in unsatisfactory surface quality (common signs of vibration) and hardening of machined surfaces. The cutting component is to make the workpiece leave the direction of the machine tool table during conventional milling, and this force is often opposite to the direction of the clamping force of the fixture, which may make the workpiece slightly detach from the positioning surface, so that the workpiece processing is in an unstable state. Therefore, conventional milling is less commonly used. If conventional milling must be used for machining, the workpiece must be clamped completely, otherwise there is a danger of detachment from the fixture. Figure 1-29 is an example of face mill milling. In this example, since the milling width exceeds the radius of the cutter, the milling is a hybrid application of climb and conventional milling. In the machined plane, the green part shown is the climb milling part, and the purple part is the conventional milling part.Minimal when the workpiece is out of contact. The tip of the knife is cut from a position with a large thickness and is not prone to slippage. The cutting component of climb milling points to the machine table (as indicated by the oblique arrow at the bottom of the right figure as shown in Figure 1-27).
The machining surface quality of the milling is good, the back wear is small, and the machine tool runs relatively smoothly, so it is especially suitable for use in better cutting conditions and processing of high-alloy steel.

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Every time the positioning cutter of the rhodium cutter is plunged, the cutting edge is subjected to a sub-large or small impact load, the size and direction of which are determined by the workpiece material, the cross-sectional area of the cut and the type of cutting. This shock load is a test for the cutting edge, and if this impact exceeds the tool's tolerance limit, the tool will shatter.
Smooth initial contact between the cutting edge of the cutter and the workpiece is the key point of milling, which will depend on the choice of tool diameter and geometry as well as the positioning of the tool. Figure 1-30 shows the smooth initial contact between the cutting edge of the cutter and the workpiece. As shown in Figure 1-30a, the initial contact is the tip of the edge, which often causes the milling width to be less than the radius of the cutter, and the initial contact with the middle of the edge in Figure 1-30b, resulting in this contact mode, the milling width often exceeds the radius of the cutter. Of course, the combination of the rake angles of the cutter also affects the way the tip makes initial contact with the workpiece, which will be discussed later.

                                                                    1-30

As a rule of thumb, the relationship between the milling width and the diameter of the tool is 2/3 (0.67) ~ 4/5 (0.8) (the milling width has a diameter).

Example: As shown in Figure 1-31, it is part of the milling cutter diameter series (smaller diameters are 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm, etc., and larger ones are 80mm, 100mm, 125mm, 160mm, 200mm, 250mm, 315mm, 400mm, etc.). Assuming that the width of the milling is 36mm, then the diameter of the first gear is 40mm, and the diameter of the second gear is 50mm, and the diameter of the selected cutter is 50mm. However, if the width of the milling is 40mm, then the diameter of the first gear is not less than this width is 40mm, and the diameter of the second gear is still 50mm, and the diameter of the selected milling cutter is also 50mm.

                                                                                                   1-31