Rolling copper

[denncarm]

Help from someone who knows what they are doing please.

I am looking at sheet metal roller's and trying to determine what thickness copper they can roll. All the one's I looked at expressed the thickness they could bend when rolling mild steel.

When you double the thickness of the material you require four times the force (everything else being the same), but the tensile strength of copper is about half that of mild steel.

From this it looks like you can roll 1.5 times the thickness of copper instead of mild steel.

Now if someone who knows what they are doing can tell me where I went wrong please.

Thanks
Dennis

[eskimo]

Help from someone who knows what they are doing please.

I am looking at sheet metal roller's and trying to determine what thickness copper they can roll. All the one's I looked at expressed the thickness they could bend when rolling mild steel.

When you double the thickness of the material you require four times the force (everything else being the same), but the tensile strength of copper is about half that of mild steel.

From this it looks like you can roll 1.5 times the thickness of copper instead of mild steel.

Now if someone who knows what they are doing can tell me where I went wrong please.

Thanks
Dennis

annealed copper would be easiest to roll ...ie I dont think copper sheeting off the shelf is annealed meaning it would require more force....so this will add in another factor to consider

[denncarm]

Hi Eskimo

To the best of my knowledge both the mild steel and copper tensile strength figures I got were for the un-annealed state but I am way out of my depth here.

Thanks
Dennis

[Michael G]

I am looking at sheet metal roller's and trying to determine what thickness copper they can roll. All the one's I looked at expressed the thickness they could bend when rolling mild steel.

When you double the thickness of the material you require four times the force (everything else being the same), but the tensile strength of copper is about half that of mild steel.

From this it looks like you can roll 1.5 times the thickness of copper instead of mild steel.


I make that to be roughly correct. To bend something you need to get the material to yield. Random numbers from the internet - yield of steel starts around 250Mpa, copper around 70Mpa. Stress in the outer layer of material is related to the thickness of the material cubed.
Taking the cube root of (250/70) is approximately 1.5.
So if you could roll 1mm steel in the rollers, you would expect to be able to roll 1.5mm copper.

However,

Copper will work harden (get a higher tensile stress as it is manipulated), and
Yields of grades of copper vary with composition and supplied condition

So while this is a reasonable rule of thumb, it may not always apply.

Michael

[denncarm]

Thanks Michael

All I was after was a rule of thumb, probably should have said it.

Where I started from was rolling some 2.6mm thick copper for a boiler which means I would have to get a roller which would roll 1.6 mm of steel.

Starting to get too expensive for the limited use it would get so I will just go to a firm with the machines.

Thanks
Dennis

[azzrock]

what some one rolled you for your copper.
aaron