Preform finishing
Slide 52
We have seen three methods to obtain the preforms for the crown adaptor. We are now going to machine the functional surfaces.
The machining programmes are created using 2D1/2 CAM.
As we saw previously, we must first of all assemble the digital model with the rough part.
There is a first assembly which corresponds to step 10, in which the lower surface is machined and a second assembly corresponding to step 20, in which the other surfaces are machined.
Slide 53
The machining assembly is designed by the software and the result appears on the screen. Unlike one-part machining, the machine set up is now complete and strict as we want to machine in series with as little variation as possible.
For step 10, the preform is laid flat on the set-up, the centering pin is conical and rests on the rough central bore, and a V-block prevents rotation.
For step 20, the adaptor from step 10 is flat on the set-up, a centering pin is positioned in the central bore and the mobile V-block prevents rotation. When the clamp is tightened the centering pin is removed so that the central boring operation can take place.
Slide 54
It is now necessary to create the machining functions by defining for each one the path to follow and the cutting conditions.
Slide 55
Before machining on the milling machine, it is necessary to make a simulation in order to verify and validate the operation.
Slide 57
In this photo it is possible to see the assembly for machining with the part in step 10 and in step 20. Once the crown adaptor has been machined, we just have to check the dimensions and the geometrical tolerances.
