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Rolling milling problem


#1

I always have the same problem when I am working with the rolling
mill . specially with the wire section the ingot
tends to bend at such point, that the rolling mill is not able to
pull it through the other side, and consecuently producing burrs
and debris afecting the quality of the work. I wonder if somebody
knows how to keep the ingot straight while rolling it. It would be
a solution for a real headache thanks in advance. Marco.


#2

Forge the ingot first as thin as possible and to the rough cross
section that you want to end up with. Don’t forget to anneal as
often as need be.

When you feed through the rollers give the ingot (and eventually
the wire) a turn through 90 degrees. This is especially important
with square and rectangular wire.

Examine the ingot at the early stages. If need be file off any
burs and flanged that get formed.

Tony Konrath
Gold and Stone
www.goldandstone.com


#3

To me it seems that due to uneven stress in the 'supply’
material, bending results. I’ve always found slight to moderate
backpull on the piece helps guide the input straight. But, the
most important factor is to anneal, anneal, anneal, very
thoroughly get an even heating into the core of the wire to
totally normalize the ingot before drawing down. It may seem
like the casting would anneal the ingot but casting stress is
very potent factor and must be relieved. Also at larger sizes I
run the wire though twice at 90 degree angles and it seems to
help. Anneal and be patient for best results anneal, anneal,
anneal, anneal, anneal, anneal.

hope this is a small help, Ed


#4

Hi Marco,

The best way I’ve found to keep wire or narrow bars straight
when rolling is by the application of tension to each end of the
metal.

On the input side of the mill, pull on the ingot/wire/bar as
though you you are trying to prevent the mill from pulling it
through. The pull should be at 90 deg to the rolls.

Do the same on the output side only pull as though you were
trying to pull the metal through the mill.

By controlling the input side, you can ‘steer’ the metal through
the rolls & pulling on the output side may not be required.

Unless you’re doing very short lengths of material this
technique requires a motorized mill or more than 1 person (or one
with 3 arms).

Dave


#5
I always have the same problem when I am working with the rolling
mill .  specially with the wire section  

G’day; I think that part of your problem could be made worse by
insufficient annealing. You must anneal after just a few
reductions, or passes, and also be very careful not to try and
roll down too much at one pass. A quarter turn of the wheel for
each pass would be plenty. And if you are rolling or even
drawing wire - be it round or square, if you don’t anneal often
enough you will feel nasty little barbs at some places.

Now, look at your ingot. Call one edge North, the opposite one
south, so west will be on your left and east on your right. If
you enter the piece in the rolls north edge first, then on all
other passes it should be also entered first. So on the first
pass, west will be on your left. On the second pass, turn it
over, so that west is on your right; the third pass it will be
left again and on the fourth it will be on your right. Rolling
or drawing like this will have the metal grains pointing in one
direction and if the piece is properly annealed and fed into the
rolls like this, you won’t get your bending problem occurring
again.


#6

Marcos, I always rotate the piece Iam rolling this eliminates
curved stock.By rotate I mean I roll it through and back in one
pass without it coming off the roller then I flip it over and do
the same step again then I turn my roller down in quarter turns
this is very important if you try to roll the piece by cranking
it down with brute force your edges will crack and your stock
will curve.Also when running it through the square wire guides I
rotate it clockwise also as I am rolling so that all sides of the
square get equal pressure applied.If you over crank when making
wire stock it squashes the gold creating wings on the edge which
will fold into your piece when you rotate it.Again small
increments when reducing your roller size will eliminate this
problem.When these wings are folded over they create voids in
your stock which when heated can create holes.I hope this helps
it is hard to visualize the process but you can try practicing
with some large copper wire you can get at the hardware store it
may help.Roll on! J Morley Coyote Ridge Studio Where the trees
are changin and the coyotes are howlin


#7

Marcos,

I have a rolling mill which I purchased used, so I cannot
account for any misuse before I acquired it, but, as I roll metal
through it, it also often curves slightly to one side (always to
the same side/direction). I have learned to compensate for this
by always placing the metal back into the rollers with the curve
pointing towards the handle. As long as the reduction pressure
and annealing are closely controlled I don’t have too much
difficulty keeping the metal quite straight during the course of
milling it down.

I also tend to straighten the metal as much as possible after
each annealing, prior to resuming the rolling process, either by
hand if possible, or by pounding it straight on a wooden block or
an anvil . My mill has a good reduction ratio but the interesting
thing is I have noticed a very similar effect with almost every
mill I have ever worked with (not that many, perhaps 5 or 6 in 25
years) and so it seems quite a typical occurrence to me. Another
helpful technique with rolling out wire is to apply a fair amount
of pressure or resistance against the metal as it enters the
mill, roll it slowly, and by straightening and aligning the
metal as it passes into the rollers this is sometimes sufficient
to help to control the tendency to curve.

If the mill is badly out of alignment and it isn’t practical to
have the rollers corrected it may be a matter of continuous
straightening and frequent annealing, but aside from being a bit
time consuming and inconvenient, it should still work out ok. A
very important factor is annealing the metal at the appropriate
point. There was a thread in the early summer about “Ripples in
metal” which you can look up on the archives for some other
rolling suggestions. Good luck, I hope this is helpful,

Michael David Sturlin, jewelry artist @Michael_Sturlin


Michael Sturlin Studio, Scottsdale Arizona USA