Re: machining teflon

Fernando,

Teflon TFE (white looks like chalk) machines like a dream. You can
use HSS tools but make sure they are dead sharp. Sharp tools will
provide a good finish and reduce heat on the part. This material is
not likely to melt during machining and you may run them fast. It
holds dimensions well but does have a property called creep. This
makes it tough to hold in a vise cause it tends to creep out almost
like trying to hold putty. A very good way to hold TFE in a vise or
fixture is to use double backed (both sides sticky) tape on each jaw
of the vise or fixture. This way you won't need to squeeze your part
so hard to hold onto it. This will greatly reduce the creep
problems. A vacuum chuck is another good way to hold this material.
Also keep in mind that TFE will move quite a bit after it is cut. So
plan on rough cutting out the shape you want, then remove from the
vise or fixture and reset up for your finish cuts. I have even
drilled and permanently inserted steel rods in large pieces of Teflon
to add support and reduce how much the material would move after
machining. I use to machine robotic grippers for the semiconductor
industry.

Teflon PFA (milky translucent color) this stuff machines OK but it
does melt so you will need to watch your cutting speed. A concern
with this plastic is that when it reaches its melting point, even
during machining, will out gas odorless toxins that will make you
sick as a dog about 4 hours after exposure. You will feel like you
have a bad case of the flu. Make sure you have adequate ventilation
during any amount of work on this stuff.

I hope this helps. Good luck with your project,

Ron Steele
http://www.stirlingsteele.com/millplans.html

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--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fernando" <fer_mayrl@h...>
wrote:

>
> Hi:
> Does anybody have experience machining teflon parts?
> I need to know what a suitable feed rate and RPM, to machine a part
> out of a 6"x6"x.75", These material is quite expensive, so trial

and

> error is not an option.
> Im affraid that it will behave similar to Nylamid or some other
> termoplastics, which melt instead of chip when using a wood router
> (27,000 RPM).
> Any input would be greatly appreciated.
> best regards
> Fernando Mayrl