Need Help!- machining plastic

[mmiranda]

Anyone have an idea on chip control while machining Delrin? Part has 3" plus turned length and we are doing on Citizen. Birdnest of chips has been nearly impossible to clear out. Ideas please.
Thank you,
Mike

[judleroy]

You can pull the material away from the part while its cutting like pulling a string. Make sure you dont wrap it around your fingers
just grab the end as it starts cutting and pull it away above the cutter if you can so it doesnt start to wrap around the part.

[John Welden]

You can pulse the feed and get the chip to break.

[extanker59]

Plastic on a swiss. I've only done it a few times in the past (previous job).
I seem to recall moving the tool away in X, moving the part out in Z to get the chips further into the work area, moving back down to close to the X, and then feeding fast in Z to push the ball of chips off.
Worth a try?

[extanker59]

Oh yeah, I forgot. Aim one or more of the coolant nozzles to try to get the chips off. We did that too.

[recordist]

Peck so the strings break, and use lots of air rather than coolant.

Strings are just going to bind, get hot, and make an ugly hole.

[ImanCarrot]

I read a good reply to a similar thread the other day (I think the poster was HuFlung)- he had the neat idea of putting a slot down the whole length of the bar- that way the string can't form cos it always gets broken as you cut past the slot.Neat idea, but haven't tried myself yet.

[Steve Seebold]

There was an article in the June issue of Modern Machine Shop about this very thing. The people in the article used high perssure coolant to blow the chips away.

[djr76]

Delrin (Acetal) should break fairly easy, the faster you feed it, the easier it should chip. I machine Delrin on a daily basis using a Kennametal WNGP-K insert.