UHMWPE troubles

[team08]

So I am trying to cut some UHMWPE and it is horrible to cut. I am trying to profile a 3d shape into 1cm thick material that goes from 1mm->7mm->1mm over a length of 120cm, raster cutting. I am using a .5" 2 flute endmill and it seems to melt the material. Recently it even wrapped around the bit and stalled my PC router. Any suggestions, or good luck with bits? Cutting out the material I use and onsrud .25" single flute cutter which works well, but I dont think it will work well for the profiling operation.

I have cut at 19,000 RPM 3in/sec, 13000 RPM 2in/sec and some in between and it doesn't seem to help. I am guessing I need a special bit, but what? Thanks.

[paco]

Hi Greg!

I'm not sure what is your problem here...

One thing I've learned with UHMW is that you should always (if possible) ramp into the cut instead of plunging to avoid material build up from long curly shavings. Use only sharp tool as the material is kinda abrasive (in fact it's puropses is to resist wear). This material usually cut very nicely... O-flute are always my prefered for plastics; single flute. If your bit get, for any reason, "plastified" from material melting, clean it right away with solvent if needed... don't continue to cut with it.

[elcruisr]

Sounds like too many rpm at too slow a feed rate. Also you should be using a tool designed for soft plastics. There is an Onsrud tool that can be fed slow at higher rpms but I'd have to get the part number off of it at the shop.

[team08]

Well I went back and used the .25" onsrud with an o-flute and again it was AMAZING! I just want something that is wider, looks like they only go up to 3/8" in this style. I cut at 16,000 RPM and 3ips. I am pretty sure you want to go as fast as possible to reduce heat on the bit, but the high rake angle is really what sets this bit apart!

[charles_o]

Check these links from a previous posThe spreadsheet or data base would be great if someone could pull it off. Until then some interesting reading and tools about this subject.

http://www.denford.com/Calculate%20Speeds.html
http://www.denford.com/Calculate%20Feeds.html

http://www.plasticrouting.com/BitSearch.asp?Page=Material
http://www.plasticrouting.com/Van.asp
http://www.onsrud.com/popChart.html