Re: machine ways

Ted,

There are 4 "engineered" plastics commonly used industrially (of
course, there are thousands; but these 4 groups are prevalent in
machinery apps)

As the grandaddy, Nylon also needs to be mentioned, as it is
ubiquitous(means everywhere!). Often it is used in a "filled" way
(with oil or grease) for bearings and sliding surfaces of many types.
Like UHMW, it "grows" and "shrinks".

1)UHMW PE- (Ultra High Molecular Weight PolyEthylene) Like super-
duper milk jug plastic. Used a lot in conveyer systems and food
processing, as it can be sterilised easily. Very tough, slippery, but
has a fair amount of movement(size change) due to temperature and
humidity

2)PTFE- (PolyTetraFluoroEthylene) also called teflon, VERY soft, when
used for linear bearings it is backed up with a harder material and
used in very thin layers. The slippery-est (lowest friction co-
efficient) stuff we have so far in commercial quantities.

3)Acetal- One trade name is Delrin. It is hard and machines
extremely well.

And finally, the one you were probably referring to:

4)Turcite- which is a combination of TFE (teflon) and acetal (delrin).
It is used as a lining of ways by many CNC and machine mfrs. And yes,
it needs GOOD lubrication system(s) for long life. It is also used to
make the nuts that drive many of our smaller CNC machines, and they
need to be properly lubed as well...

http://www.polymerplastics.com/ is one good site for engineering
plastics information

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., "Ted Walls" <tiffyted@l...> wrote:
<snip> Some modern industrial machines use quite a soft plastic
> bearing material (can't recall
> its name) for the bearing surfaces which if not well lubricated
> becomes useless after a very short period.
>