Cutting UHMW Plastic 5/16" Thick

[David Iannone]

Rochling Enginering Plastics called UHMW. Stock Code 12371 5/16" Thick.

I just cut some test samples out using a Onsrud #63-712 1/8" Upspiral. I am cutting on a PRT, Porter cable router. Using screws and tabs to hold down.

Has anyone else cut this stuff? Is this the best bit to use on it? The cut was OK, a lot of chatter marks. This plastic is VERY hard. He brings me 4x8 sheets by the dozen and I cut about 50-60 parts out of each one. They are constantly changing the parts though, so a vacuum hold down wouldn't work. We have done over 700 of these parts out of PVC which was a breeze, but they are now changing to this new plastic.

Anyone heard of this?

[Greybarn]

I have cut some UHMW and have had the best results with a spiral O or upcut bit. If you are getting chatter marks, then slow down the move speed and/or increase the RPM. I had pretty good luck using some Spray 77 adhesive on the bottom surface to hold it down, but it was a pain to clean off. Double sided carpet tape probably would work also.
Regards
Peter

[knight_toolworks]

actually it is a pretty soft plastic and it never really cuts cleanly. vacuum would hold the sheet down but never the parts. Only if you leave an onion skin will vacuum work. once you break that the pieces will slide around and lift up.

[bobmoore]

ultra high molecular weight polyethylene is pretty soft as steve said. Best to contact a top notch tool manufacturer like vortex or onsrud, tell them what you are cutting it with and they will help with bit selection and feed rate. I have always used O flute single ce and pretty fast feed rate. Also uhmw is pretty inert so if you use adhesive don't stress it too much or it will peel off the plastic an shoot parts around the shop.
Bob

[knight_toolworks]

Plus the shavings can can be real long and clog things up.

[sailfl]

David,

Try a 65-012.