Machining Delrin

redvan22

redvan22

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Hi,
What sort of tooling is needed, if any, to machine Delrin in a lathe?

I would think HSS with a high top rake and perfectly honed rounded point for a smooth finish. Am I in the right ballpark?


Mike.
 
Yep. Works great for me. I machine a lot of acetal. It cuts like Delrin. Got some UHMW to try and that was a mess. Never use that again.


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redvan22 said:
Hi,
What sort of tooling is needed, if any, to machine Delrin in a lathe?

I would think HSS with a high top rake and perfectly honed rounded point for a smooth finish. Am I in the right ballpark?


Mike.
Click to expand...

I think you're halfway in the right ballpark. High side rake will speed chip flow, thereby reducing cutting temperatures. Back rake will thin the chip and also speed chip evacuation. Delrin cuts best with an edge, just aft of the nose radius, so you need to turn the tool to make contact with that area. The whole idea is to use a sharp edge and reduce heat as much as possible because Delrin and most plastics melt if heat is too high at the point of cut. Accordingly, slower speeds and faster feeds while using an edge instead of the nose radius will give the best results.

HSS, ground well, will work best but a sharp CCGT insert, turned to utilize the edge, will work nearly as well.
 
I'm with Winegrower, whatever is on the lathe at the moment will work fine. Delrin is probably the best machining plastic there is.
 
Agree with Mr Whoopee, I mostly use a TPG insert with radiused nose for nearly all work. and all metals. Delrin needs nothing special in the way of cutting tools Acetal is just a generic name for the same substance as Delrin.
 
Agree on how wonderful it machines. That said, be careful using large (>1/2") drill bits in the tail stock. If you aren't careful, the Delrin will grab it and attempt to "screw" the drill bit into the work, especially when using drill bits to enlarge holes only a small amount. The key is slow feed.
 
Last edited:
kb58 said:
Agree on how wonderful it machines. That said, be careful using large (>1/2") drill bits in the tail stock. If you aren't careful, the Delrin will grab it and attempt to "screw" the drill bit into the work. The key is slow feed.
Click to expand...
Also, you can grind a small flat on the cutting edge of the drill to neutralize the rake, called a "brass edge" This will prevent hogging in.
 
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