Hello Guest it is July 17, 2019, 09:38:42 AM

Author Topic: Turning UHMW Poly on CNC  (Read 6101 times)

0 Members and 1 Guest are viewing this topic.

Turning UHMW Poly on CNC
« on: November 16, 2005, 08:22:15 PM »
"UHMW machines very easily to a smooth surface, but in lathe turnings come off as a long string that must be prevented from wrapping around the work piece.


Found the above quote on a source supplier for UHMW poly, and they are right, turnings do come off in a long string, But how would one prevent the swarf from wrapping around the work piece?  I'm using 1/4 HSS ground and polished, with a chip break groove, lots of relief clearance, front and sides. positive rake on the cutting tool. But the swarf wraps around the work in to a ball of what looks like fishing line.

I'm turning flanged bushings, 4 to 8 at a time using UHMW poly on a mach 3 controlled lathe.

Ideas on how to improve? links, help sites? tool design? feed rates, speed?




« Last Edit: November 16, 2005, 08:25:00 PM by RGB Specialties »
Re: Turning UHMW Poly on CNC
« Reply #1 on: November 16, 2005, 09:46:41 PM »
O BOY I do this all the time! There is not much you can do... Okay there are a few  thing...
1. Crank the speed and feed! You can shoot the chip away from the part if you work at it
2. Put something to suck up the chip as it comes off the part
3. if you can use a cold air gun
4. Keep your hands OUT!

This is what i do, It is not fun but it works.

Hope that helps
Brian
PS Up the feed :)
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: Turning UHMW Poly on CNC
« Reply #2 on: November 17, 2005, 08:00:20 PM »
Thank you I'll try that, faster is better huh? who da thunk it? question, what to you believe the fastest surface speed obtainable without a cold air gun would be using HSS?

I tried running 300-600 RPM , fairly high feed rates and seemed like i was getting better chip control cause it was making bigger chips at the slower speeds running around 350-400 rpm or so on 1.250 OD stock, so Guess I was thinking the opposite had to be true? Glad I asked.

Offline DAlgie

*
  •  304 304
    • View Profile
    • Algie Composite Aircraft
Re: Turning UHMW Poly on CNC
« Reply #3 on: November 17, 2005, 11:49:02 PM »
A three jaw chuck is also trouble, the jaws catch the chip string as it comes off and then it's time to empty out the chip tray around the chuck! Other problem with a 3 jaw is it acts like a big fan and the air swirl goes back behind it, sucking the strand with it into, yes, the chuck again. If you can use a collet chuck it's a bit better as there are no jaws to fan the chips or catch them as they come off the part. Don't try to leave the machine unattended for very long or scrapped parts often results!
Re: Turning UHMW Poly on CNC
« Reply #4 on: November 20, 2005, 09:47:48 AM »
Yeah to bad there isn't a canned cycle like the G83 for chip breaking on drill operation. I bet someone could write a wizard to do it though. Cut a bit and back up and cut a bit more. Should work good on rough passes.
Re: Turning UHMW Poly on CNC
« Reply #5 on: November 20, 2005, 02:10:30 PM »
I think there is... it is 1083.m1s

I found it
' DRill G83 X (optional)  Z (mandatory) Q (Mandatory) R     
This should work for drilling

Hope that helps
Brian
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: Turning UHMW Poly on CNC
« Reply #6 on: November 20, 2005, 03:48:09 PM »
I think there is... it is 1083.m1s

I found it
' DRill G83 X (optional)  Z (mandatory) Q (Mandatory) R     
This should work for drilling

Hope that helps
Brian


Yeah that is what I was about except of regular turning. The same sort of motion control that G83 gives for drilling.