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Instruction Guild for Rolling Mills


#1

Dear Noel,

You should definitely not try to resurface the rolling mill
yourself. I would suggest you contact a company in Pawtucket, RI
named International Rolling Mills. Their phone number is
401-722-7811. When you call have the model number and name of the
mill handy. They used to resurface mills and should still do it.
They may also be able to re-harden the steel for you.

It may be cheaper to get a new mill, but it is worth a shot.
Good luck,


#2
     Don't know what kind of mill you have but Cavallin recommends
that both rollers be reconditioned at the same time. You can take
them to a machine shop and ask that both rollers be ground exactly
the same amount, then case-hardened to 0.040"  (40 thousandths). 

Elaine, Noel and all, If you were to take your rollers to a machine
shop, give them specific instructions that main part of roll must run
true with bearing journals. Normally between 1 and 10 thou taken off
will clean up all marks and as Elaine advised both rolls need to be
done so that the diameters are the same. However, with respect, you
would not need to re-harden the rolls after taking this small amount
off.

You would not be able to re-harden after grinding in any case - roll
will turn black, roll will distort, roll will probably crack. Plus
the fact that special hardening processes is involved (will not go
into it now) and it would be very difficult to find a company to do
this even if it were possible. (would possibly cost more than a
Rolling Mill). Also, a hardness depth of 0.040" would not be deep
enough to protect the much softer sub surface, which would collapse
under pressure.

Sara has asked me to mention (as Janice did last week) that we now
have our detailed instruction manual for Rolling Mills on our website
www.durston.com. This can be viewed online or can be downloaded in
pdf format. One reason we put this online is due to the large
response we had from Orchid earlier on in the year, offering our
instruction manual via post. Also included in this is some techniques
of jewellery manufacturing which we have reproduced by kind
permission of Sandra Noble Goss.

Craig Martin
Technical Division


#3

Hi Noel, A good machine shop in your area that has a precision
grinder should be able to resurface your mill rolls. A lot will
depend on how the rolls are made. Typically items like this are left
with centering holes in the ends of the shaft. If these are present &
not damaged the rolls may be mounted in a grinder & reground. The
amount that must be removed is dependent on the deepest dent in both
rolls. The both rolls must be ground to this level.

If the grinding needs to go below the hardened level (if the rolls
were case hardened) they’ll have to be rehardened. The folks at the
machine shop will be able to answer this question as a result of the
grinding.

Dave


#4

I have always heard that an off centered grinder is the best & most
accurate method of grinding rollers to keep them in round? Of course
this has to penetrate the deepest marring & case hardening would be
required afterwards. Perhaps Matthew or Sara Durston might enlighten us all?