High Temp Plastics

How do we classify teflon?

I don't think Teflon^® will withstand the temperature. How about graphite, or would dust be a problem?

What will be the working temperature range of the oven?

The only information I have is it needs to withstand 600 degrees F working temp.

Dust is an issue.

600F is just about too much for any common polymer.

PEEK or polyimide may work.

Torlon, polyamide-imide might make it.

I'd suggest a visit to US Plastics, Ryan Herco, Harrington, or DuPont or Boedeker.

I've been away too long to be current on the new materials.

Can KEVLAR meet your demand?

TMO Kevlar Fiber Data

Yeah use steel. 600°F is higher then the rating on most hi temp plastics. As a wear item would not be very cost effective. Most of these are pricey.

Another option is idler sprocket to hold it up. Place idler in clevis connected to air cylinder. Let the air hold tension on the chain so it doesn't droop. If the run is long additional idlers along it.

I have thought about this... and I may just look down that road.

It sound like you're looking for a polymer/ceramic component, that is if cost is no object

You may find that some of the older style "thermoset" plastics are able to satisfy your need. Those used for switchboards like Bakelite and such might be suitable.

My experience though has been more to look at the properties needed, so rather than specify "plastic", specify a material in terms of friction, machinability, thermal stability (including expansion coefficients) and so on.

You might like to look at "reflow soldering machines" as these are ovens similar to what you described. From memory they used SS skids for the conveyors, the only "plastic like" material I sighted inside those was the insulation on the heater wires.

Does it have to be plastic?

I'd consider ceramic. It can be molded to any shape you want and fired in an oven. If you have it glazed, you might not ever have to replace it.

Or maybe silicone:

N. Temperature Resistance
Temperature extreme stability is silicones most outstanding property. Under normal operating conditions temperatures as high as 600 F and as low as -150 F do not destroy the physical and electrical properties of silicone. At elevated temperatures, the tensile, elongation, and abrasion resistance of silicone is far superior to that of most organic elastomers.

http://albright1.com/types-and-properties/

Graphite might work nicely:

http://www.azom.com/article.aspx?ArticleID=1630

Hi RVZ,

I think it's been said already, but 600F is pushing things a bit for 'plastic' materials. The highest I am aware of is in the Polysulfone family. It can operate continuously at 300F, and push to 350F, but I'm not aware of anything higher than that.

In the thermoset materials (phenolics, Bakelite(tm), polyimides), even they cannot continuously handle more than 300F.

If 600F is your true requirement, you'll need something else.

Kind regards ...

PEEK and ULTEM may work. Working temp above 500F. 600F doubtful.

http://www.aetnaplastics.com/products/d/Peek

http://www.sabic-ip.com/gepapp/Plastics/servlet/ProductsAndServices/Product/series?sltPrdline=Ultem&sltPrdseries=Highest%20Heat&search=Search#searchresults

Have you looked into glass-reinforced plastic (GRP)?.....

See http://www.ecfibreglasssupplies.co.uk/t-GlassReinforcedPlastics.aspx

Won't even get close to 600. At 600 it will be black in 24 hours and crumble soon after.

want to avoid fibers and dust as much as possible.... I think I may end up with bronze guides.

http://www.high-temperature-composites.com/high-temperature-composites-and-fire-barriers-pyrosic-pyrokarb.htm

Thermoset has some advantageous properties with regard to friction and high temp, but 600F is perhaps the high limit. We use polysufone for some very high temperature parts, but our customer is not forthcoming with exact, specific details of their device or it's true temps of operation. Another option is using a metallic filler to transfer heat more efficiently. Though I have only experience using stainless steel filled plastic, and used as an electrical conductor and not a heat conductor, there may be a usable similarity in characteristics for your application. I also see no reason why, say, a copper fiber could not work. Just a thought. Oh and for the life of me I cannot remember the base plastic resin used with the SS. But the final product is an electrically conductive plastic radio face plate which also serves as a ground and electrical shield.

I have to update my comment from above. I am COMPLETELY WRONG. While the melt temps for certain plastics I have used are considerably above the 600F design temp, they will still degrade at an enormously accelerated rate making them a poor choice. Also my possiblity of using metallic fibers to help with heat dissapation creates design problems that would also preclude practicality. I am sorry to have wasted your time.

I've consulted with a colleague over the weekend and have come up with no evidence of plastic in that temperature operation.

Soldering reflow ovens use extruded alluminium guide rails (with obvious allowances for thermal expansion).

Again I ask "Why do you specifically want "plastic"?" Why not look at the issue from the point of required/desirable properties and open the field to other materials.

Some sintered metals might provide the properties you need (without outgassing that will happen with plastics) and give greater wear resistance.

Suggest you go and look at "Piza Hut" or similar and see what they use in their conveyor ovens.

The request for plastics was driven by the customer. From the beginning i thought it was a non-starter, but I like a challenge, and thought... hey, it's been a while since I looked at those materials, maybe some fancy new advancements have been made since my last search.

I think I will ultimately go with bronze guide rails for cost and ease of machinability.

Thank you all for your input!

-R