PTFE or not

Hi everyone I landed on about 7 kilos of plastic, rod, bar and block.
Mainly in white but there is black, blue.
Now I wish to give some if this away to variose club members but want to know what I am giving them, On one of the white bars is stamped BS EN 15860 but web site gives no info on if it is Nylon, Acetal, PTFE. Suspect it is Acetal as it came out of an engineering workshop. But would like to be sure.

I stuck a small block on the mill and it machines nicely.

Thanks
Bob.

There's a useful guide here

Russell.

I would be very wary of inhaling burnt of burning plastic. Many are very toxic

Jopo

PTFE, very good for bearings but expensive, has a greasy feel is almost (always?) a off dull white shiny finish and is heavy compared to nylon, acetal, pvc.Bit heavier than Delrin but easy to confuse. PTFE machines very well and takes a good finish with a hss flat or slightly negative rake tool with a stoned radius. Back off drills or they will pull in (same as brass)

Do not inhale dust or fumes - wet polish and grind only

Jopo

Beware of names when dealing with plastics. SAfter all Delrin, amongst others, is really only a brand name for Acetal. The same applies to many nylon based products. Colour is usually an irrelevance as they can be and often are many colours.

Delrin is the DuPont brand name for acetal homopolymer resins. There is a familiy of different grades of Delrin (as is the case with many plastics). You might find some copolymer products described as acetal. Different manufacturers may use slightly different processes to produce chemically similar products, and there may well be subtle differences between products from different processes.

Most polymers can get very complicated if you start to look into the fine detail, and that's before people start modifying their behaviour with any additions.

BTW - don't be tempted to try burning tests on anything that might be a fluorinated polymer (including PTFE). People have died (Hydrofluoric Acid is VERY nasty and can be formed when these are burned).

if the products are nylon then the colour refers to the hardness and machine-ability

white being the softest then Blue and finally black, there are If I remember 2 more colours in the set

all except white are good bearing materials with low co-efficient of slip and excellent machining qualities - used in the print/packaging industry all the time

cheers

.

See here, for some thinking

and here, for a typical MSDS

If I recall correctly; there were a couple of cases in the late sixties, or early seventies, where someone accidentally contaminated a roll-up cigarette with a strand of PTFE swarf. This is a very good way of ingesting the products of combustion! ... We were certainly made very aware of that risk when I worked at Kodak.

MichaelG.

When I worked in the food industry conveyor chains used to run on green 'plastic' (of some description) strips which were of low friction, even less friction when conveyor lube (a sort of soapy water) was sprayed on.

Never knew what the stuff was called, was always referred to as "that greeen stuff". Anyone know what "that green stuff" was called?

Chris

Edited By ChrisH on 18/09/2013 23:21:40

Colour is usually of minor significance with regard to either properties or identification of polymer type - most polymers can be coloured to any of a wide variety. Some pigments will alter other properties to a degree.

Some companies however may always purchase particular polymers in specific colours to aid internal identification (or to make any bits that fall off show up in the food).

Friction properties can often be modified by incorporation of various additives. The specific behaviour you witness may not be a natural property of the polymer - this can make identification even trickier.

.

Possibly UHDPE

MichaelG.

I note with interest Michael's post above which links you US sources.

If you don't have an interest in safety of chemicals don't bother reading ths, it's tedious but as this is my day job I feel I need to contribute to the sum of human misery by a short teach-in.

Regrettable these give a somewhat restricted view of the toxicology of PTFE.(Cas RN:9002-84-0). Congess has recently decided to implement the GHS (Globally Harmonised System of Classification and Labelling) to address shortcomings in the present system,which willin the future require any MSDS to actually provide information rather than generalities. US MSDSs are not valid in the EU.

The relevant EU document is known by the acronym SDS (Safety Data Sheet). These contain specific information conforming to regulation and based on validated testing regimes.The ECHA (European Chemicals Agency) based in Helsinki is managing the REACH system and publishes various pieces of data. If you go to their website **LINK**
and key into the search box the CAS number 9002-84-0 (not forgetting to tick the agreement box you will find the EU Harmonised classification which indicates in coded form the various hazards of this chemical.

Further searches within the ECHA website will reveal the basis of this information; which is backed by peer review. Details of how to carry out such searches are beyond the scope of this post.

I warned above that this was going to be tedious.

In the end the ECHA classification confirms that PTFE is as bad, possibly worse than Michael has indicated.

Happy reading.

Jerry

Jerry,

Thanks for the info.

MichaelG.

I hear that PTFE is to be withdrawn from use on the likes of fry pans in the next year or so. Ian S C

Quite, however that data sheet said, "cautiously smell the fumes". The nose is very sensitive and can detects smells at very low concentrations, well below dangerous levels. However, if you are not sure of what you are doing it's better safe than sorry.

Russell.

Wow
Thank you all for your replys even had a member want me to send samples to his lab
I do not smoke have not done for 50 years,

Once again thanks
Bob