High Tensile Strength Non-metallic Screws

Hi I am seaching for some high strength non-metallic screws. Just wondering which material offers the highest tensile strength.
Thanks philip
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How about alumina.. http://www.smallparts.com/products/descriptions/hbc.cfm
or PEEK.. http://www.netmotion.com/htm_files/ot_screws.htm
-scott
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Philip wrote:

Without knowing your application, it is a bit tough to suggest a non-metallic material such as an oxide/non-oxide ceramic or polymer. Also, depending on cost several more exotic options may exist. A litte more detail and the suggestions will abound.
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The screws are intended to tighten two plates with a narrow channel of fluid flowing in between. As the ineternal pressure can be up to 2 atm, i'm sourcing for screws that can withstand this load. As for why the need to be non-metallic, it is to avoid interference with instruments.
philip

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fluid
be
What kind of interference? Electric or magnetic?
--
melon



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magnetic. u probably guessed it. we're going to conduct experiments using mri. so the material has to be non ferro, para magnetic. To be on the safe side, i would prefer polymeric materials. Peek might be ok, but i'm not sure. Is there anything that has a higher tensile strength than peek? Of course, it must be available off the shelf...

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IMO regular nylon 6/6 could do. Stronger, but harder to find are GRPs like 30% glass reinforced MXD6 polyamide. Instead of guessing I would calculate load per bolt and then check with catalogues.
--
melon



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Philip wrote:

Depending on how many of the screws you have to bolt the platens and their diameter several choices could exist. One option would be the polymer route which would also be the most cost effective particularly with molded thermoplastics. Further carbon fiber reinforced polymers would add significant strength, but you would probably have to have them machined.
On the ceramic side there are also several choices. Aluminum oxide ceramics can be machined into various bolts and screws and there are several manufacturers that do this sort of work, but for added toughness SiC screws would probably be the best choice. I had several 1/4" Silicon carbide bolts fabricated several years back for a high temperature testing rig and while always using appropriate tighting torque never broke a single one.
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You didn't specify the diameter. I have found that the nylon bolts used to hold down toilet seats to the toilet hold up quite well. Another possibility are the nylon screws used to fasten license plates to cars. They truly take a beating and hold tightly for years. And all are relatively cheap!
Al
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