typical leaf spring electrical contact forming ?

[coppercone2]

So I considered a simple structure, such as leaf spring RF gasket strip. The shape is somewhat simple, the idea is you get a small flat line of contact with a plate when you screw the thing together.

As far as materials go, you can typically get sheet metal something like
1) full soft
2) half hard (or fractions hard)
3) full hard
4) spring temper (is this different then full hard?)

Now, lets say you get the spring temper metal sheet. And you cut into it, so you have a shape that can be bent into a contact.

Do you just form it to get the right shape with the starting temper that you have, or do you have to do additional work hardening steps to get the contract functional? I.e. it would be considered a useless bend step, because you can theoretically get the correct shape through less amounts of bends. Kind of like if you are making something from a paper clip, you might want to bend it back and forth a few times before you shape it to get it toughened up.



I would assume they just focus on shaping it, and not 'working' the material during the forming process??? i.e. least amount of steps required to get the correct shape.

With a spring, you only form it to shape and possibly heat treat it afterwards. I never saw anyone doing anything 'funny' with spring manufacture. Are contacts the same?

And, for plating, do they consider the surface strain effects of certain plating to be part of the springs behavior? i.e. that you have to plate after you bend, for spring reasons? (because I only would consider plating after bending if It has something to do with crack formation reduction, rather then considering the plating to be 'finishing' the behaviors related to the 'spring constant" of the structure.... possibly having to do something like choosing a plating process that is high strain to 'adjust' the spring. Again, to me it seems like this would NOT be what they do.


And I mean for a real contact, where you spec out the starting material, not super mcguyver repairs with improper starting materials.

[TimFox]

I needed some custom-shape BeCu springs, to be fabricated by the Physical Sciences machine shop at my university.
Following instructions, and datasheets from the alloy manufacturer, I had the shape formed from half-hard alloy (commercially available), then carefully tempered following the detailed instructions from the alloy company.
(Exact temperature and time recommendations differed between different BeCu alloys and initial states.)
A simple jig ensured that the shape was dimensionally correct, and was used to hold it at that shape during the heat treatment.
Don't forget to pull out the engineering handbooks to calculate the stress within the alloy when it actually does something springy:  since the sheet is thin, the stress (in psi) within the alloy can be surprisingly large, and you don't want to exceed the "elastic limit", past which the part deforms even if it doesn't break until you reach "tensile strength".

[coppercone2]

that sounds like conventional spring making, it does not appear they want you to work harden anything. (mechanical hardening)

But.. does the stamping on a line factor into this? Or can basically all contacts be made in the way you describe? Is there some annoying shit where you NEED to 'strike' or otherwise bend-harden the metal? I know its possible but it seems like it would be extremely annoying to figure this out and I hope its avoided in the industry?

Like processes reminiscent of forge hardening or whatever. I am wondering if they have tiny little hammers or something doing something very specific. For large structures I know they might peen or shot blast things. But for tiny springs its unheard of ... right?

I heard of some stuff with pneumatic crimpers have some kind of performance increase because they 'strike' the crimp but its all described as being equal spec ...  I thought it was some BS to try to sell big machines to do little work (all my literature tells me that HOLDING the crimp might actually be better then rapid production with strike hammers)... but I don't know if this relates to leaf spring parameters for manufacture... it starts to feel like meta materials territory



Thermal or possibly chemical hardening seems like a good way to process a dimensionally correct tiny spring. Work hardening the same thing seems like insanity.

[TimFox]

Like thaumaturgy, metallurgy is a black art.