F1 Plastics selection help

[cdc02254]

Hello,

Im after some advice on plastic selection.

I have designed a device that will be used in all F1 events. The devise will be located in a position that could and probably will receive impact from cars. The device itself is sprung loaded so when it is hit it will retract but it will receive impact from the underside of a car. Initially I selected nylon 66 but am now having some doubts after some testing. The item itself is about 150mm x 15 x 40 an would need to be machined from a block.

One of the main criteria is that the item does not break or crack. It can deform but I do not want it to break.

Can anyone suggest a good plastic that will suit my application.

 

[CoryPad]

polyethylene (low stiffness and strength, though)




Regards,

Cory

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[patprimmer]

Polyethylene will probably do it and is cheap.

Polyester based elastomers such as "Hytrel" or "Arnitel" will do better but are quite expensive.

Polyurethane will also do it.

Santoprene or super tough nylons or super tough polyesters might do it.

Regards

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[cdc02254]

Ok,
Thats a start.

Maybe one point I was a bit mis leading with is the fact that the component needs to be stiff, but will not crack or break on impact.

Regards

 

[CoryPad]

Ah, that's the rub. Polyamides (aka nylons) in general are good for applications that require stiffness and toughness. Or, you can use a polyolefin (PE or PP) and increase the thickness to increase the stiffness.

Regards,

Cory

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[patprimmer]

If you choose nylon, it should be extrusion grade or impact modified grade AND it should be properly moisture conditioned before use

Regards

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[Pud]

You could have a look at cast polyurethane rubber - comes in multitudes of stiffnesses, and can be cast in simple silicone rubber or alloy moulds.

Very tough, abrasion resistant, low cost tooling.

It is almost impossible to machine conventionally, but water jet cutting works fine for profiles from pre-cast sheet/blocks (if your design allows this...), when then you would have no tooling costs as such.

Rgds

Harry

 

[bvanhiel]

Metal.

If you're machining out of a block, want stiffness and ductility, then why not a piece of steel? What properties are you looking for that push you towards plastic?

-b

 

[patprimmer]

Low specific gravity might be the issue

Regards

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[cdc02254]

Hello,

Metal is not an option for me, basically the FIA will ot approve the use of my design if it is from metal on safty reasons.

I guess I want a plastic that I can machine and has the properties that a block of ALI would have but isnt metal.

 

[Plastserv]

Try Dupont super tough nylon. I believe it is called ST 801. This material has been used for sprokets, and was originally developed for automotive fasteners that were driven in with hammers.

 

[patprimmer]

I believe I already recommended impact modified nylons without promoting any particular brand name.

Regards

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

 

[dwightdixon]

Ultra high molecular weight High density Polyethylene is close to the properties you need and is commonly machined into sliders for snowmobiles and many commercial conveyor usages. Fairly cheap and no tooling costs.