Brass versus Copper

[Transient1]

Hello all,

There is a part that consists of two thin flanges directly opposed to each other. When they are flat together, they form a rectangle. The flanges are bent up to form a gap. The question I have is, since brass has a higher ultimate strength than copper does that mean once it is bent into shape it will hold its position better than copper?

Thanks.

 

[apsix]

I'm not sure what section you are trying to form, but brass has a yield strength typically about 3 times that of copper, so yes, it will 'hold its position better than copper'.

 

[Transient1]

Thanks for confirming that, it's what I figured.

 

[rb1957]

are you concenred with the spring-back from the forming operation ? ... wouldn't this depend on E (and a host of other varibles) ?

 

[apsix]

I may have given the wrong advice.
If it is spring-back that you are concerned with, as per rb1957's post, copper would probably perform better.

 

[Transient1]

I am worried about spring back. The modulus of copper is slightly higher than that of copper. Can you give any further advice on spring back?

 

[rb1957]

not my speciality, but i think it's trial and error ... i would expect the material with the lower E would spring back slightly more, but it may also be affected by the strain rate of the forming operation, the temperature (tho' you'd think that'd be the same for both operations), etc.

i assume you're going to weld the mating edges ... would allow for some mismatch (at the cost of some internal stresses).

how precise does your finished product have to be ? this'll affect the process ... if not very precise, then welding the sides (which will make the edges align) but will also cause a slight curvature of the other faces of the box (as well as internal stresses)

 

[Transient1]

Well actually, these tabs are positioned in an electrical circuit to form a capacitor. Therefore, its important that they maintain their shape as best as possible, otherwise their capacitance will change over time. Brass has performed well enough, just wondering if copper is as good or better as we got a lot in of these tabs made with copper.