Need Help!- Milling Peek/Peek Optima

[MicroMachine]

I was wondering if anyone knew some speeds, feeds, chip load, etc for milling Peek.

We are making spinal implants from Peek Optima and we are not allowed to use any liquid coolant of any kind. We are currently using a cold air gun to minimize burning of the material which is also not allowed. Currently we are having most of our issue with a 3/32" carbide endmill milling a pocket with a tolerance of +/-.001". Any help would be better than nothing since this our first experience machining Peek dry.

[judleroy]

Try using high helix endmills. Spindle speeds from 5-8000 on that small a cutter. Feed at 20-40 ipm. Faster if your cutting less than 3/32 deep. Judleroy

[judleroy]

Peek is very expensive I know so waste is a big problem. Once you find the sweet spot its smooth sailing. Judleroy

[mactec54]

Hi MicroMachine
You can use coolant on medical parts you just have to get it approved I use GreenCut
which I can supply, some medical related parts I make in Peek low spindle speeds & feeds it machines very well there is 96 cavities with a .0001 tolerance in photos

Your cold air blast can cause more contamation than using approved coolant

[chuck_hobby]

Mactec54,
Beautiful parts, what are they for?
How do you get the nice smooth finish on the PEEK...is it polished or is that the machined finish?
I do some similar custom parts for a client in Teflon...whole different set of machining problems.
Thanks for sharing,
Chuck

[mactec54]

chuck_hobby Thanks, I can't say what they are for, but medical related

Thats straight off my machine I do all types of plastics,aluminum,Titanium,steel,
toolsteels, with the same kind of finish my Teflon looks like that as well

[MicroMachine]

Thank you! We wound up getting our chip load up to .001" which seems to be working on standard Peek we are setting up on. I know my last company used coolant on some Peek drivers we made for surgical drills, but these are spinal implants & our customer prohibits any liquid from being used. The machine had to be completly sterilized prior to even running these parts as well as any tooling or measuring equipment which will come in contact with these parts. I will try the higher helix endmills to see how they work compared to a standard helix.

I will look into the cold air gun, but I am pretty sure we have a filter on the line which our customer required when we asked to use. I am still open for any more suggestions regarding Peek.

[mactec54]

Hi MicroMachine

Start your speeds around 2850rpm feeds to match, forget you even know about chip load, you may be able to have more speed with high helix cutters, but if your parts are hard to hold, then these cutters won't help to much as they try to pull the small parts from your fixture's

Your air should be fine if you have the filters (around 3 micron or better) like you said in your last post