Springy sheet brass?

Is there a type of sheet brass that has a spring charactersitic?

I have an application, or I should say I might have, for a flat brass sheet spring about 25mm x 75mm by about 1mm thick. I need to be able to put a slight bend of a few degrees on a long edge and to use this edge to apply pressure.

I could use clock spring material but brass would be much better.

Any suggestions please?

John

Brass can be hammer-hardened ... but have you considered using phosphor bronze ?

MichaelG.

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ferinstance: https://www.rapidonline.com/phosphor-bronze-sheets-520937

Edited By Michael Gilligan on 15/05/2021 16:06:07

Brass shim (at least the english version) is fairly springy, and it comes in a roll or strips about 100mm wide. The name of the product is hard-rolled brass if you are searching in places where 'shim' is not understood. 1mm thick is fairly thick for shim, too, as it normally ranges in steps from 0.002 inches up to 0.015" or a bit more. Try for 0.04 inches as that is a knats over 1mm.

If you know of a jeweller or anyone who might have a precision roller, you could ask them to roll your strip to the thickness you need.

Regards, Tim

Brass is a poor material for springs but clockmakers do work harden brass to give a degree of spring tension. The way that I usually do this is to put a ball peen hammer in the vice with the ball pein up and work the brass by light taps with a second hammer using the raised ball pein as an anvil. Overworking the brass will cause it to work harden too much and crack. The brass is, not surprisingly, thinned out some due to the hammering so you need to factor this into your calculations.

stainless steel may well be more suitable........

Bronze may be a better option an does not look too different.

Molybdenum copper

Beryllium copper is used for non-ferrous springs.

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Not arguing, Clive [you are obviously correct] ... but I'm interested to know if there is any useful advantage [except for its high electrical conductivity] over phosphor bronze.

MichaelG.

Relay contacts springs used to be Beryllium copper, I was taught as an apprentice at GPO phones to reshape them by stroking them with smooth jawed pliers.

Oops. Meant beryllium, not molybdenum.

Be careful when machining beryllium copper, Beryllium is poisonous when ingested.

Brian

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Don't think I would be trying that with: 25mm x 75mm by about 1mm thick

MichaelG. [wimp]

Indeed, he needs a hell of a spring. You can with 10thou thick and 3/16 wide springs

Perhaps the greatest advantage of BeCu is that it can be formed in the annealed state and then heat treated at about 320C to develop the spring properties.

Regarding the hazards of BeCu, this is from a hazard data sheet:

Non-hazardous operations
General handling, stamping and forming, many machining operations, medium temperature
hardening heat treatments, cleaning, plating, soldering and general assembly and disassembly
operations are considered safe and do not require specific controls other than general levels of
ventilation.

It goes on to state that certain grinding operations producing dust in a certain size range can cause a reaction in some sensitised operators.

Rod

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Thanks, Rod ... I didn’t know that ^^^

MichaelG.

Well thank you all for the suggestions and ideas. i wanted to use brass because of the colour match and it seems I can probably achieve enough 'spring' by careful work hardening. Hard rolled brass might well fit the requirement if I can find a suitable thickness.

This is all a bit experimental and there might be a trade-off between hardness and thickness, Is there possibly a grain orientation requirement when considering a bend?

John

Thanks for this idea Bob, needless to say it worked

John