How do they make...?

[sPoNiX]

After reading the "how do they make steel wool" thread above has got me wondering..

How do they make copper "solder ring" fittings?

I can see that the actual copper part could be bashed out by a big machine but how do they get the solder into the groove on either end?

You could sit there for days trying to get the solder into the groove with a blowlamp/soldering iron and never achieve it.

The joints don't appear to have any discolouring due to heat.

So..how do they do it?

sponix

[Dave Plowman (News)]

I'd imagine it's cold rolled into place.

[Merryterry]

Good ones have the groove tinned before the lead free solder is cast in. The inside is then rebored to size. The lack of discolouration is due to the fact that the solder melts at a lower temperature than needed to discolour the copper and the whole lot is burnished to finish.