CNC machining of turbine

[turkmentari]

I am trying to find out whether a 4 axis CNC mill is capable of rendering a turbine disc as shown in the photo. I think that it has a bit complex geometry of which 3 axis CNC would be unable to produce.

thank you for your helps.

[crazythunder]

It might do it with the right tools, but a 5 axis would be your best bet. I could make something close on a 4th axis, but i could make it exact on a 5th axis.

[RotarySMP]

Turbines are made of high temp super alloys (which are a beast to machine). They are cast under vaccuum. Normally a pattern is machined to make the wax turbine, which is then investment cast.

That built up part with the blades welded on is most likely a Nozzle guide vane assy ins't it?

[vulcom1]

Mark,
I agree with you on the turbine disc as being cast except that you can make one for the Kamp's book turbine by turning a disc then cutting the profile of the blades and twisting them by hand. There is a lot of grinding after for the profile. He reccommended stainless steel or better but with my KJ I purchased the turbine which is cast and is certified for a lot higher rpm,125K versus 80K. He also mentions to watch for elongation, stress cracks and any other fatigue problems do to the high heat and rpm.
The ngv can be made by lathe and probably cnc but it is not as much of a problem. It does not rotate and the rear part encases the turbine. Besides needing the small clearance on the turbine it also serves as a shield if the turbine comes apart. The blades are welded in with a tig welder and cleaned up with the lathe.
The compressor you need is the 66mm 2038 which should be purchased and the other part to make is the shaft and spacers. To me there is not much work for a cnc on the rotating parts but making the diffuser is another matter.
John

[Delw]

you can make that part with a 3 axis machine and a cnc indexer (4th axis) using a ball endmill. of coarse you will need the right cad cam software. full 5 axis would definatly be the way to go.


one of the shops I worked at many many years ago made the real ones from investment castings. one thing I notice is that in the models is that some problems are the blades coming off at high rpms.
this can be fixed by drilling a hole in between the each of the blades and then adding a rivet in the hole.
this way your blades will flex a tad.

Thats what I was told by the engineers that we made the parts for , was that the holes we drilling in them were for flexing this way the turbine wont blow the blades at high rpm if something gets into the turbine, From constant start up and acceleration. The rivets were so the blades wouldnt bend to much.

I been reading this forum for a while now trying to figure out how to build one(2) for a f-4 phantom I want to build.