Face rhodium
End mills can be used as face mills. However, because its entering angle is 90°, in addition to the main cutting force, the tool is mainly radial force , which is easy to cause deflection and deformation of the tool holder , and is also easy to cause vibration, affecting the machining efficiency.
Rhodium on the side wall
Most workpieces suitable for machining with end mills have one or more sidewall faces perpendicular to the bottom surface (which is parallel to the spindle of the milling machine), which presents a problem that is not present in face milling: the problem of sidewall shape and accuracy.
Figure 3-3 shows the sidewall surface formed by the circumferential teeth of the end mill. It can be seen that the side wall surface is made of multiple arc wraps. Similar to the bottom surface formed by the fillet of the face milling cutter insert, the flatness of this envelope is related to both the tool diameter and the feed per tooth, as well as the radial circular runout of the cutter teeth. If part of the cutting edge is not on the cylinder of the circumferential edge of the cutter, this sidewall will be out of the correct shape. Some indexable end mills have this problem, which will be discussed in the indexable end mills section of this chapter, Section 3.3.
3-3
The problem of climb milling and conventional milling has been discussed in Chapter 1, Section 13 of this book, and this is also the case with end milling. At the same time, since end milling often uses smaller diameters and longer overhangs to machine sidewalls, its climb milling and conventional milling will bring about changes in the accuracy of the sidewall machined surfaces. Shown in Figures 3-4 and 3-5 is a schematic diagram of the forces on the end mill when milling the sidewall of the end mill. It is important to note the radial component of the cutting force. The effect of this component is to pull the workpiece towards the tool, and the reaction force on the tool is to pull the tool towards the workpiece (not plotted on the force diagram). The result of this action and the overhanging of the tool is that the tool has a tendency to "get in", resulting in a "gouge" phenomenon (also known as "undercut", see Fig. 3-6a) at the root of the sidewall of the workpiece.
3-5
However, the radial component of the cutting force in climb milling has the opposite effect. The radial component of the cutting force of climb milling causes the workpiece to have a tendency to leave the tool, and the reaction force of the workpiece to the tool also pushes the tool away from the workpiece. The result of this action and the tool overhang is that the root of the sidewall of the workpiece is relatively separated from the tool, resulting in an "undercut" phenomenon (see Fig. 3-6b).
Therefore, if an end mill is used to make a slot, whether it is a through groove mill or a closed keyway, if the groove width is equal to the diameter of the milling cutter, that is, both sides are cut at the same time, it must be up-milling on one side and conventional milling on the other side, and the forces on both sides and the overhang of the tool deflect the tool, resulting in overcut on one side and undercut on the other, as shown in Figure 3-6c.
a)overcut b) undercut c) the sides are overcut and undercut respectively
Types of end mills for CNC machining
There are four main types of end mills for CNC machining:
