The term 3-axis milling refers to the three linear axes on a machining centre, or formerly a milling centre. The designations of the three linear axes are X, Y and Z. These are determined in the standard DIN 66217. The spindle axis, where the mould is clamped, is the Z-axis. With 3-axis milling machines the following processes can be carried out.
- Drilling: All drilling is made in the Z-axis. The drill is clamped in the spindle, the machine runs in the Z-axis with the programmed feed against the spindle and in doing so creates a hole.
+ Screw holes, holes for ejectors, threaded holes, etc. in any kind of plate are the applications for this machining method.
- 2-axis route milling: A milling cutter is moved in the X-Y plane directly from one point to the next at the programmed speed. Here the cutter can move in both axes or in just one of them.
+ Pockets for inserts or wear plates are manufactured for example with route milling. The mould moves along the linear axis until it reaches the end point. The end point of the first route is simultaneously the start point of the second route.
- 2-axis path milling: In path milling, movement is not made directly from one point to another point, but on a curve or other path. In path milling, always both axes move (X and Y).
+ Circular pockets, or the bottom area of a level mould contour are examples of uses for 2-axis path milling.
- 2.5-axis milling: Here the third axis, the Z-axis, comes into play as an infeed axis to enable milling at an angle. Many paths are milled one after another in the X/Y plane. After every finished path, the Z-axis is changed by a defined value and the next path is milled.
+Most roughing operations are done with this milling method. Process a plane, adjust the infeed angle, and process the next plane. Many finishing operations are also done by 2.5-axis milling.
- 3-axis milling: All three axes move simultaneously to manufacture a 3-dimensional body. During 3-axis milling every axis can be used as infeed axis.
+ 3-axis milling is mainly used for finish milling. Large areas are mostly finish milled with a zigzag movement. This machining is usually carried out with a ball-nose milling cutter.
Figure 1 shows 2.5-axis milling on the insert of our container. It is machined path by path and at the specified position the Z-axis is the infeed axis. On the left the extract of the CAM program (see Section 9.1.3) is shown and on the right the milling simulation.
Figure 1: 2.5-axis milling [Source: Cimatron GmbH, Ettlingen]
In Figure 2 the insert for our container is milled in two different 3-axis milling operations. On the left the mould contour is processed by 3-axis milling in a zigzag movement at a 45° angle. On the right the same mould insert is milled in a spiral movement from top to bottom. Both are 3-axis milling operations. There is no definition of movement axes and infeed axes. Depending on the angle of the mould and the contour, everyaxis can be the infeed axis.
Figure 1: 3-axis milling [Source: Cimatron GmbH, Ettlingen]