Plastic selection for higher temp use.

I am looking for a good type of plastic to use. This will be for a clamp that clamps a cable onto a form and goes through an oven. This is for making coil cords, like an old fashioned coiled telephone cord.
Temperature is 250 degrees F.

I made a prototype out of Udel or Poysulphone material. This is rated for a high enough temperature. But, it seems a bit brittle for long term repeated use.

The forms have a cord wrapped around them, and are sent through a "pizza oven" type oven on a metal belt. The plastic part is a clamp on each end of the coil to hold the coil in shape and under pressure.

Something like UHMW would be tough enough to outlast all the abuse the operators might dish out, but the temp rating is not that high, ( or is it?) A chart from Plastics International suggest that UHMW is rated for 200 degrees F short or long term.

What I would like is:
Temperature resistance for 1000's of cycles to 250 deg. F.
Higher coefficient of friction, for gripping.
Toughness.
Reasonable price.

The polysulfone looks OK except for the perceived brittleness, and price.
PTFE is great for temperature rating, but has a low coefficient of friction.
Polycarbonate looks almost tolerant of the heat, and a high cooefficent of friction.
Delrin has a short term toleration of the heat, but I am not sure about the long term toleration of heat over 200 deg. F.
Nylon may or may not tolerate the heat...

Any suggestions?

Help!

Other characteristics include not marking or transfering marks to the cables. This is very important, mechanically, the shape is critical, but also any bleed out of colors or transfer from one cable type to the next will be important.

Phenolic/ Garolite, they have different heat ratings but G7 or G11 should do it.
Rulon can take a fair bit of heat but price is nuts. plain teflon is probably way too soft eh?

UHMW - High Temp

McMaster-Carr McMaster-Carr lists a High Temp. UHMW rated to 275 F. They also offer an "additional information" contact. Ph. # 562-692-5911. Hope this helps.

At work we have a 3D printer that uses PPSF (polyphenylsulfone), it has a glass transition temperature (Tg) of 372 F. Not sure about brittleness after repeated cycles or prolonged use.

Price is nuts: SP1 vespel.

Otherwise it fits the bill completely.

Radel - polyethersulfone that's glass filled.
Radel® A PES, Glass Filled : Polyethersulfone, Glass Filled : PES - Emco Industrial Plastics
Polysulfone, Polyethersulfone, Polypropylene, polymethylpentene, polypropylene copolymer are about the only thermoforming plastics that will take temps over 121C. That's the autoclave temp spec'd by FDA.

Polycarbonate will lose considerable strenght with repeated exposure.
JR

Ultem should be perfect for that application.

PixMan said:

Ultem should be perfect for that application.

Click to expand...

Took the words right out of my mouth! X2! Great stuff.

PEEK?............ high temp capability and strength plus it's not quite as spendy as ULTEM.

Spec sheet

http://www.directplasticsonline.co.uk/pdf/Peek_Datasheet.pdf

I am so bewildered.
PEEK according to my chart is 4.2X expensive as ULTEM.

McMaster confirms.
Ultem 2" rod $66.40 / foot
PEEK 2" rod $216.00 / foot
Polysulfone 2" rod $46.00 / foot
VESPEL 2" rod $3376.92 / foot

Ultem is a little bit more $ than Polysulfone, the chart shows it to be about 3X the price of Polysulfone, but quotes for the two materials were not that far apart.

How tough/brittle is Ultem?
Polysufone "feels like" it will shatter if dropped on the cement. It did chip a little bit when machined, that usually tells me it will like to chip or shatter or break.

Vespel seems like a ludicrous price.

If all of these plastics are "suitable" then the next selection might be the price comparison.


Thanks for all the ideas

Another vote for Ultem. Last I bought was cheaper than PEEK. either virgin or glass filled.

Is this a batch mode, or a continous mode?

I understand the batch mode allows the straight ends to be a desired length.
In that case, couldn't the straight sections be brought out of the oven through hollow tubes, and the ends clamped outside the heat?

I understand the continuous mode really wouldn't need any clamping in the oven, because the oven would have a long capstan with the cable wound around it, slowly moving to the cooling chamber.

Are you sure you need to clamp inside the oven?

Are the plug ends molded on? In that case, does that end need a clamp?

And the other end terminates into a device case, where cosmetics isn't an issue?

3t3d said:

I am so bewildered.
PEEK according to my chart is 4.2X expensive as ULTEM.

Click to expand...

Sorry guys.

Must be the difference between the UK and US - 'twas 'tother way round a month back.

3t3d,
how big a piece you need for a sample? I have a few short pieces of 2.5" Ultem I believe. I could send you a piece to play with.

the temp ratings for the better nylons look fine to me, probably much cheaper as well.

MatWeb - The Online Materials Information Resource

Ryton - which is a PPS resin.

Some properties for various Ultem polymers:

Boedeker Plastics : Ultem PEI PolyEtherImide Datasheet

A few others:

Comparison Table for Plastics.

SND said:

Phenolic/ Garolite, they have different heat ratings but G7 or G11 should do it.
Rulon can take a fair bit of heat but price is nuts. plain teflon is probably way too soft eh?

Click to expand...

I second the Garolite. I had a stupid customer that had a design on a rectifier box that a few of them caught fire in the field and others got very hot. I am pretty sure they went past the 285 degree rating, but the Garolite held up even better than what it was rated for. Even on the aluminum boxes that went up in flames the Garolite insulators I made were discolored but intact and not brittle.

PixMan said:

Ultem should be perfect for that application.

Click to expand...

Exactly. I think you can make cookie sheets from Ultem (350F).

Thanks for all the ideas.

Tony, the part is 1.75" D and 1.25" long. I can get a piece locally, Thanks! for the offer.

Garolite is another possibility.

The cables are wound onto a SS rod, from 3/16" diameter, to 1" diameter.

What I did was make an offset bushing that clamps onto the rod. The plastic part swivels on the offset bushing, and has a "pin" that when rotated will clamp the wire against the rod, and the wire is wound up on the rod for the length of the coiled part. Another clamp grabs the other end, and the 'tails" are tied back as needed.

Basically it holds the wire/cable tightly in shape while it is being formed.
There are MANY sizes of part number being made, so I set out to make a "universal" jig to use for any part number in production, without needing to have dedicated tooling and to make the process as fast as possible, and less strain on the operators.

So, the plastic part is a donut with an offset hole in it that fits over an offset bushing clamped to the rod. On the face of the donut is a finger that clamps the end of the wire. The harder the wire pulls, the harder it clamps down.
This arrangement will clamp quite a wide range of size wires/cables.

There is a snap ring to retain the donut on the bushing. Very simple really.

Thanks for all the ideas and leads.