Strongest non-metallic screws?

Hi:
I need to replace some 4-40 stainless steel socket cap screws with non-metallic ones.
Nylon is an obvious choice, but I'm not sure if it is strong enough.
Any stronger non-metal materials from which screws are made?
Thanks.
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Good day!

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There aren't too many non-metallic options for 4-40 socket cap screws, assuming you mean socket head cap screws. Ceramic might be an option, but finding a 4-40 socket head cap screw in ceramic will be difficult. I have seen ceramic 4-40 hex head screws.
There are many more material options in larger sizes, but 4-40 severely limits your options. Some other non-metallic materials available for larger screw sizes are Teflon, PVC, and fiberglass (I think its actually polyurethane with glass fibers). You might be able to find some of these materials in 4-40.
Is there any chance you could use a high quality stainless steel that is non-magnetic? Alternatively, could brass or aluminum be used? I realize these don't meet your requirement of being non-metallic, but I'm trying to offer some possibilities without knowing the details of your application.
--
- John

John Eric Voltin
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Why dont you use a non magnetic stainless 304-311 grade What are the parameters you need to achieve

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Chris Carlen wrote:

Silly me I thought you guys were in NM
If it's got to be plastic rather than just non-magnetic metallic
then your best bet is soem sort of glass filled plastic
http://www.craftechind.com/FINAL2020pdf/41-45.pdf
look on "page 43"
been a while since I've done any work in minature plastic but nylon or delrin would be good choices but there are more exotic plastics as well. Whether you can get screws in them off the shelf?
you can PayPal my consulting fee..............
cheers Bob
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On Wed, 22 Feb 2006 14:50:00 -0800, in sci.engr.mech Chris Carlen

Since you are in a laser and electronics group I'll ask the question, are you sure non-metalltic is enough of a specification? Or do you need some specific dielectric properties? As to strength, since you provide no load info you'll have to assess that yourself at this point. -- Ed Ruf Lifetime AMA# 344007 ( snipped-for-privacy@EdwardG.Ruf.com) http://EdwardGRuf.com
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On Thu, 23 Feb 2006 04:53:00 -0500, in sci.engr.mech "Ed Ruf (REPLY

Also McMaster-Carr carries ceramic machine screws and nuts, tensile strength of 4400 psi. As well as polycarbonate, nylon and PTFE.
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On Thu, 23 Feb 2006 04:53:00 -0500, in sci.engr.mech "Ed Ruf (REPLY

Also found PEEK http://www.designnews.com/article/CA120447.html
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Chris Carlen wrote:

I'm not sure how readily-available it would be as a pre-made screw, but Garolite is good stuff. It's easy to get the material.
I have a project now where I'm using Garolite G-9 and threading it with 8 mm fine threads and it is as strong as brass (which is what it replaced). It is dielectric, non-magnetic, and easy to machine.
Don Kansas City
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Drake Plastics makes screws from Torlon and PEEK
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Harry Andreas
Engineering raconteur
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Chris Carlen wrote:

There may be alternatives to using non-metallic (plastic or ceramic) screws. You haven't said why you need a nonmetal, so that makes it difficult to suggest solutions.
If you need a nonmetal to electrically isolate a piece, you can use a metal bolt and nut if you put a plastic washer under the nut, and a plastic sleeve to isolate the bolt from its hole.
Olin Perry Norton
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