2.5D and 3D Machining
2.5D machining is when all the machining is in the same plane and that plane coincides with one of the planes of the milling machine. For example, a slot drill cuts the part shown above. The cutter plunges into the billet (move in Z) and then cuts the profile with a series of X and Y moves.
Setting tool paths for 2.5D machining is generally simple and quick and a vast range of parts is made this way. Code listings are relatively short and are pre-processed rapidly by WELmill in preparation for machining.
3D machining is when surfaces are cut which lie on different planes and which may be other than the three major planes of the milling machine, for example, the faces of a pyramid or surface of a hemisphere as shown above. 3D machining requires all three axes of the mill to be able to move simultaneously.
Depending on the profile required, slot drills, bull nose or ball ended cutters are used for 3D finish machining. Slot drills or end mills can be used for roughing.
Manual creation of NC code for 3D machining is not a realistic option. The mathematics involved is formidable and a code listing is likely to have many tens of thousands of lines. Use 3D code generating software.
What WELmill Does
WELmill frees the Emco mill from its limitations and enables it to do 3D machining using data from very long code listings, something impossible with its native controller. It can take WELmill several minutes to pre-process a 3D code listing in preparation for machining. A precise time cannot be given as it depends on the length of the listing and the speed of the PC. Once the code is processed, the machining time will be the same regardless of whether or not the PC has a high specification or is the lowest we recommend.
3D machining can take a very long time even on fast, modern machines and especially if a high quality finish is required. A ball-ended cutter leaves parallel rows of cusps over the cut surfaces. To reduce the height of these cusps, the parallel passes of the tool must be closer together. If the distance between passes is halved, the machining time doubles. The diameter of the ball ended cutter comes into the equation too: the smaller the diameter, the greater the number of tool passes.
If 3D machining is being done with a ball-ended cutter, the cutter will cut into the material on which the billet is standing. This ensures that the profile of the part is completely cut. It is essential that the billet is standing on some suitable thickness (at least equal to the diameter of the cutter) sacrificial material which will not damage to cutter. It is likely that the cutter will need a safe, clear space all round the part. Plan work-holding with great care!
3D Machining Tips
CNC File Specification for WELmill