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Old September 16th 06, 05:13 AM posted to rec.crafts.jewelry
ted frater
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Posts: 133
Default rolling mill questions

br wrote:
Hello all,
I've been a lost-wax caster for over thirty years, and I never really
learned to use a rolling mill. I never even bought one, because I could
always figure out how to get along without it. I have several questions for
you bench experts concerning rolling gold wire. For an upcoming line, I need
long bands of 18K yellow gold to then have disks punched out, 1/10th. of a
millimetre thick and 8mm in diameter. How many operations/reductions am I
looking at to roll down a 1.2mm wire to a 0.1mm x 10mm ribbon? Is this too
thin to be done reasonably? Could I do this, with good repeatability
(thickness-wise I'd like to stay between 0.09mm and 0.11mm), using an off
the shelf rolling mill? Do standard mills have well polished rollers, and
will I have a problem getting an easy polish on the ribbon after the final
reduction? I'm hoping to need about 10 meters a year, lets say 1000 pieces.
What are the do's and don'ts for doing these myself? Perhaps I'd be better
off getting them made? I have kilns and temp. control for annealing. That's
no problem. I'd appreciate any and all ideas, comments, etc. B.RANDALL
http://www.srdfrance.com



This one is something I can help you with.
Putting it simply, a rolling mill makes metal thinner IN the direction
of the rolling.
IE your 1.2mm wire will go down to the thinness you want BUT wont get
any wider!!.( ok I know there will be someone who will say it actually
does get wider by about 2/4 %)
If you want to go wider IE to make the ribbon you describe you will
have to cross roll the wire. the length you can do this with is the
width of the rolls.
so if yor mill rolls are say 5in wide, youll be able to work a 4.5in
length of your wire. This is going to be difficult in handling and
placing the wire just right so it gets nipped by the rolls and flattened
across its width.
not the way to go
Now to produce the width you want youll need to buy a 10mm wide piece of
gold and roll that. NOT wire
I say 10mm wide ans youll need a bit of spare each side of the punch dia.
also your punch and die tolerances will have to virtually zero and
sharp. also youll need to punch it hard not annealed.
Youll need a good quality mill.Because the thinner you go the greater
any lack of parrallelness will show up on the rolled metal. ie it will
come out curved. so you then have to turn it over to get it straight again.
If you take all this learning curve into account, the cost of the mill
setting it up etc youll find it cheaper to buy it in from the bullion
dealer already rolled, assuming it is listed in his catalogue.
As for the finish. Rolling to a high finish is also difficult. Most
rolls are grouind finish not mirror.
Hope this helps.


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