Machining PTFE

The very characteristics which make teflon slippery also make it tricky to machine. You are right about the drill. When cutting plastic especially ones like teflon, polyethylene, Delrin, etc. I use only brand new very sharp cutters. Even a cutter that has only cut aluminum will still leave burrs. Sanding and moving from coarse to fine will work but plan on taking a long time. The abrasive paper will mostly push the burrs back into the hole. One option is to use a fine scotch brite pad ( the red one ) and spin it individually on each hole. This will work if the burrs are not too bad. Another option is to scrape the burrs off with a very sharp tool such as an x-acto knife. Other sharp deburring tools are made by Noga and can be purchased via MSC.com.. If you have a lot of holes this could be very tedious. One other option is to get a very shallow countersink, maybe 120 degrees. Make sure it is very sharpand run at very slow rpm. Don't try to use a drill for this because it will chatter and gouge your parts.

there is an acid they use to etch PTFE before

they attach an adhesive maybe this will do it

Re-machining the dimples fractionally deeper, with a different cutter possessing positive rake, front clearance on the flutes and razor edge sharpness will slice away the burrs. Because of your screen name and the style of dimpled PTFE discs, this sounds like a structural bearing application, so I would be very hesitant to use abrasives! One of the fine characteristics of PTFE as a bearing, apart from its low coefficient of friction and its equality of dynamic and static coefficients, is its embedability.

So, please don't spoil the bearing performance - doubtless scoring the opposing mirror-finish faceplate - by using abrasives! A proportion of any grit will embed itself nicely in the PTFE surface, irretrievably.

Even if you don't notice embedded grit from the use of abrasives, despite the usual silicone grease applied to such structural bearings you will, over time and cycling, score the mating face. Bearing performance will worsen over time and somebody will find out your secret. That somebody will probably have a lawyer.

Mark
www.fluoroplastics.com

Great point Mark. I never did like using abrasives on soft plastics. Now I know a really important reason why. Thanks!

Instead of a drill bit - use your bell end!!!

Thank you all for the information. Very good. Most helpful. And, just in time! Again, Thank you.

One other question. What solvent that can be used to clean PTFE without compromising COF properties?

Rubberman,

Any of the common non-oily solvents such as acetone, isopropyl alcohol, even methylated spirits, is acceptable. Watch out for two aspects: If the PTFE is microporous (common fault in thin directly-molded sheets) beware of the filth you want to remove being washed into the micropores. I'm a fan, therefore, of detergent and water and a clean cloth.

Use of water/detergent also solves the other issue - static electric discharge inflaming a solvent! Vigorously rubbing PTFE with a cloth and flammable solvent is quite a risk of fire. Please don't let anyone get hurt that way. None of the above is likely to affect the CoF as it's a bulk property of the material, not just a surface property.

Regards,
Mark
www.fluoroplastics.com

Mark, et al,

Thank you all for your useful input. Very helpful, enlightening. I am on the road to doing great things....

RM

Chamfering before cutting would have been a possibility.

Whatever you do, donot try to melt or burn off. Fumes are toxic.

Perhaps you could make for yourself a manual; "dimple reamer" tool which wouldhave multiple edges and could be manually twisted in each dimple to separate the burrs.

I reload ammunition, and I use a primer pocket reamer for assuring I get pocket clean so primer will seat correctly.

milo