Composite Coil Springs 2

[ulrichAT]

I am looking for coil springs made of fiber reinforced plastic. Does anybody know, where I could get such springs?

Thanks a lot for every hint,
ulrich

 

[israelkk]

I don't think that you will find one on the shelf. You will have to custom order them to your requirements.

http://israelkk.googlepages.com/home

 

[TVP]

http://www.sardou.net/accueil4.htm

 

[vti]

Try Heli-cal Corp. They machine springs from any type of bar stock.

http://www.heli-cal.com/

 

[israelkk]

vti

Before jumping to the state of the art and most expensive spring manufacturing process, a normal standard wire coiled spring has to be checked. Anyway, ulrichAT is looking for springs made of composite materials and I assume he has good reasons for it.

 

[ulrichAT]

Thank you all for the input. israelkk is right, I need a composite spring, because steel springs are to heavy for our application. Titanium is too expensive.

TVP, thanks for your link, this is quite what I'm looking for. But this company is located in France. Do you know something similar in the US?

 

[TVP]

ulrichAT,

I do not know of any company other than Sardou that makes helical springs from fiber-reinforced polymer matrix composites. I know Hexcel was working on composite leaf springs, so you may try them. Have you discussed your application with TIMET? They have worked on some solutions that can lower the cost of titanium, including the new alloy TIMET LCB.

 

[israelkk]

ulrichAT

Can you provide the weight, size, force, deflection etc. that are required from the springs.

May be an optimize metal spring can do the job or get close?

 

[ulrichAT]

@israelkk: No, a steel spring cannot do the job, we know that for sure.

@TVP: Thanks for the hints, I will check that.

Both of you thanks again for your help,
ulrichAT

 

[israelkk]

ulrichAT

Did you try a preset (scaragged) spring? It can take up to 70% more stress then non-preset spring.

 

[ulrichAT]

Ok. israelkk, I need a coil spring, which has a working travel of approx. 2 1/2" and a spring rate of approx. 400 lb./in. The weight of the spring must be lower than 450g. The spring has to make about 100000 strokes in a highly dynamic mode.

If you can give me a steel spring which meets these requirements you will make me very happy!

Regards,
ulrichAT

 

[GregLocock]

You need to specify the maximum and minimum loads as well.

Also, what friction (or damping) is acceptable.

I suspect that nothing short of a diamond will meet that spec, due to the weight requirement. That in itself looks rather arbitrary, since it is almost exactly one pound in the old money.

Cheers

Greg Locock

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

 

[ulrichAT]

GregLocock, these values are not arbitrary at all, but of course the values are rounded.

But you are right, we also believe that you cannot meet this specification with a steel spring. What we try to find out is, whether it is possible with a fiber reinforced material or not.

What do you think? Is it possible to reach this goal with FRP? If yes, do you know a company which could build this spring?

Best regards,
ulrichAT

 

[israelkk]

After investing some time I am convinced that a helical compression spring made from a metal wire can be designed to deflect approx. 2.5" from free position to give the ~1000 lb force and 100000 cycles and weigh 1 lb.

http://israelkk.googlepages.com/home

 

[GregLocock]

Hmm, I can't design one to weigh that little with a stress range of less than 1000 N mm-2, which is not going to last for 10^5 cyles.



Cheers

Greg Locock

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

 

[TVP]

Israelkk,

What "metal wire" type did you use for your analysis?

 

[unclesyd]

As sugested by vti the use of a machined spring should be looked at, especially the multistart variety. Since I lost my spring (smarts and step) some time ago I can't offer any particular direction.

Aside from the aformention Helical Springs here are two other manufacturers of machined springs.

http://www.abssac.com/product.asp?productnum=9&catnum=2

http://www.taylordevices.com/MachinedSprings.htm

This information is from my buddy who works with weird science and engineering secret stuff.

 

[ulrichAT]

Israelkk, you make me curious. Can you give me a little bit more information about this spring? What metal did you use? Titanium?

ulrichAT

 

[ulrichAT]

unclesyd and vti, I will investigate the machined spring option. Thanks for the hint.

ulrichAT

 

[Fabrico]

Air bag.