Plastic Coil Spring 1

[kthree]

While I understand why plastics my not be the first choice material for long lasting coil springs, I am interested in whether or not plastic coil springs are being manufactured anywhere. We have spent the last year or so following leads for plastic coil springs. No big successes yet. Any info anyone would care to share in this matter will be greatly appreciated. Thanks, K.

 

[israelkk]

Metal coil springs are made of wires by special bending are coiling machines. Plastic wire are not common and the spring making machines will not work on plastics. You could use mold injection to create a plastic spring however, plastic has one major problem it can not hold a load for long, it will relax. I recall someone made springs out of a composite materials such as Kevlar but those are for very specific and special use.

 

[patprimmer]

Carbon fibre composite can be used to make a good spring, but costs are very high.

i have only seen leaf springs of carbon fibre, but torsion bars should also be possible. I expect that a coil spring could be made, but it would be somewhat more difficult to fabricate.

Thermoplastics will be a lot more difficult due to creep under load, which cause sagging to occur to much greater degree than steel springs.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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[kthree]

Thanks israelkk and patprimmer for considering and responding to my post. The RFQ's we've received were interested in plastic especially for it's nonreactive and nonconductive properties. Am I correct in understanding a carbon fiber coil spring will conduct electricity? We've come to a standstill in our search. Any suggestions of how to search for papers or articles that may exist which discuss plastic coil springs would be greatly appreciated. Again, Thank You, K.

 

[CoryPad]

Carbon fibers can conduct electricity. If you need a non-conducting composite, try Kevlar or Glass fibers.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[kthree]

Great, Thanks. K.

 

[patprimmer]

Aramid fibre (Kevlar is a DuPont trade name for Aramid) are non conductive and have a much higher modulus than glass fibre, but not quite so good as carbon. If the conductivity of carbon rules it out, Aramid is probably OK.

Aramid fibre is very good in tension, but very poor in compression as it fibrillates in compression, so this needs to be considered in the design.

DuPont and Akzo are the only really major manufacturers of Aramid fibres, and they should be able to help with info on Aramid fibre applications.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[kthree]

Especially because "Plastics" is an area of very little experience for us, this quest for Plastic Coil Springs has been, at the very least educational. Everyone's responses add to our knowledge base and help us take another step toward our goal - Thank You.