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Laser cutting


#1

g’day folks I’m looking for a laser-cutting business with the ability
to cut accurately right through 0.5mm silver sheet using
highly-detailed .ai or .eps files for input. I’ve already done a heap
of running around and found many businesses who can’t do this so
please don’t suggest a contact unless you know they actually have
this capability.

Thanks
Al Heywood


#2
laser-cutting business with the ability to cut accurately right
through 0.5mm silver sheet 

Hi Al,

I looked into this several years ago, after admiring laser engraved
wood carvings. What I was told is that silver is so highly reflective
that it presents a technical problem for the laser, and is either
impractical or impossible to laser engrave or cut. This made sense to
me, since silver, I believe, is the most reflective metal on earth.

It is possible that technology, or creative technicians have
advanced since my inquiry… laser welders were virtually unheard of
in the jewelry industry at the time. I’d love to hear that it is
possible!

All the best,
Dave

Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#3

Hi Gang,

What I was told is that silver is so highly reflective that it
presents a technical problem for the laser, and is either
impractical or impossible to laser engrave or cut. 

I’ve heard the same thing from my local shop with a laser cutter.
According to them, it’s also true about gold. I’ve also heard from
someone else, but not had it confirmed by anyone actually trying it,
that painting the silver or gold surface with a black magic marker
or blueing it with layout blue will enable gold & silver to be cut.

According to my local folks, who’ve tried cutting silver & gold,
what happens is refelected laser pulses burn holes in the bellows &
other parts of the equipment. They can also be reflected back into
the laser tube itself( a high priced part to replace). At the price
of industrial laser cutters (in the 6 figure range), I can’t blame
them for not wanting to mess with the stuff.

One other option you might try is water jet cutting. Water jet
cutters use a garnet ladden water jet under extremely high presure
to cut a part just like a laser. One of the drawbacks though, is the
width of the cut. Many water jets can cut a .020 or .040 inch wide
kerf. The laser is closer to .010 inch. I’ve had 4mm silver cut with
a water jet. Thickness is not a problem for water jets. They can
easily pierce 6" thick steel or rock.

Most laser or water jets require a DXF file as input.

Dave


#4

Yeah Dave, I’m probably expecting too much, but if you don’t ask and
my envious good wishes for your return to paid employment - take me
with you ? I’m getting tired of telling people I’m in it for the
lifestyle and not the money

Al Heywood


#5
What I was told is that silver is so highly reflective that it
presents a technical problem for the laser, and is either
impractical or impossible to laser engrave or cut. 

it’s not just the reflectivity. It’s also silver’s very high
thermal conductivity. It’s difficult, even with the speed of a
laser, to overcome the rate at which the metal conducts the heat away
from the point the laser hits. Silver takes perhaps the highest
energy levels of the jewelery metals to weld in a laser welder, and
even then often the welds tend to be brittle. it’s the only of the
jewelery metals where the common practice is to use a filler wire in
welding, made of a lower melting alloy, instead of the same metal
one is welding. One CAN weld with sterling filler wire, but getting
good welds is hard to do, so many folks use a filler wire made of one
of the grades of ordinary silver solder. I’ve used both medium and
hard solder, with not a great deal of apparent ifference between the
two. so usually I use hard solder to draw down filler wire for use
with sterling. The actual weld will have a higher heat resisting
ability than would a solder joint with hard solder, since the
welding operation does mix the filler wire in with a bit of the
parent metal, to a greater degree I think, than dissipation of the
solder into the parent metal during most soldering operations.

Peter


#6

Hi i’ve been reading the thread about laser cutting with some
interest and thought i’d pass on some about a similar
process that i have used very successfully here in the uk - wire
eroding - you’ll need to track down a company specialising in
presicion engineering, but it’s a great technique using vector based
files from your pc that are then used to cut stacks of silver sheet
so that 5-10 pieces can be cut in one go depending on the thickness
of the silver.

good luck and best wishes from sally in bristol, england where
spring is creeping up slowly:-) – @sally1
http://www.inspirals.co.uk


#7
 One CAN weld with sterling filler wire, but getting good welds is
hard to do. 

Peter-- When and why would you weld silver, rather than solder
it? Is this distinct from fusing? Thanks for the clarification,

–Noel


#8
     One CAN weld with sterling filler wire, but getting good
welds is hard to do. Peter--    When and why would you weld silver,
rather than solder it? Is this distinct from fusing? Thanks for the
clarification,    

Noel, I was referriing to the use of a laser welder. Laser welders
are capable of joins in pieces which cannot be conventionally
soldered, due to heat sensativity, since the overall piece need not
become all that warm, even though the weld area itself is hot enough
to fuse metal. It doesn’t do quite the same type of joint as
conventional soldering, since the laser is “line of sight”, and
penetrates only so far into the surface, while solder can flow along
a well fitted capillary seam to areas you cannot see.

In laser welding, just as with electric arc or other oxy/acteylene
welding on steel, etc, one usually needs to add additional metal to
the joint, and this is usually done by using, as a miniature version
of a welding rod, very fine (.25-.30 mm, or thereabouts) wire of the
metal being welded. The laser then not only melts the joint area of
the pieces being joined, but also a bit of the wire, with each pulse,
so that you build up, with successive passes, a weld bead, and can
build up the joint area above the original surface if you want, or at
least, to a level full join, just like a solder fillet, if you like.

My comment was that using sterling silver or filler wire can be
difficult, since welding sterling silver or fine silver takes rather
high power levels with the laser, and also, especially with lasers
that don’t offer pulse shaping, it can be sometimes difficult to weld
silver without getting cracking of the welds, since a laser weld bead
is often highly stressed and work hardened metal as it first comes
out of the laser. The use of a different, lower metal alloy, like
silver solder, as the filler wire, helps to solve these problems.

The question of when you’d torch fuse silver, vs torch soldering it,
simply depends on what you’re doing, and whether you can tolerate
solder, with it’s lower melting point and sometimes color
differences, in your seams. The question of whether to laser weld a
joint, vs soldering it, isn’t just related to silver, but to all the
jewelery metals. Laser welders do some things much better than torch
soldering, such as highly pinpoint joints that don’t disturb
neighboring metal, the ability to actually build up the metal with
weld beads, rather than jost join two pieces, and the ability to
control the heat damage that can occur with soldering (including, if
you don’t want it, annealing.) Since first getting a laser to use at
work, I’ve become totally hooked on these machines, to the point of
buying one for the personal shop too (an old beat up and therefor
cheaper one, to be sure, but i still spent/borrowed more to buy the
old laser than i did for my much newer (though also used) Corolla…

Nevertheless, lasers have their drawbacks. For one thing, despite
the precision, sometimes the joint is actually not as clean. Solder,
done well, can be an almost invisible capilary join. Laser welds can
be small, but they do have width, and the deeper penetration you need
into the metal, the wider and more disruptive the weld can get. So
though laser welds can avoid solder discoloration, and can avoid
joints coming apart with subsequent heating, or things like that,
sometimes they need more clean up than a solder joint does. And,
joining larger pieces of metal, can mean several overlaid passes
with the laser to get a fully filled joint, often having to then
repeat the process on the other side of the joint too. Though the
laser is very fast on a per pulse basis, it often takes a whole lot of
pulses to actually complete a joint, and sometimes, by the time you’re
done, you’ve spent considerably more time laser welding a joint than
it would have taken to flux the thing and flow some solder in with a
torch.

I often use, in building pieces, both soldering and laser welding,
rather than just one or the other. Often, I’ll use the laser to
discretely tack pieces in position for subsequent soldering. That
solves all the juggling around and third hands and other tricks to
try and hold pieces in position for soldering, while still giving me
the clean capillary joints of a solder seam where I want them.
Saves me a LOT of time… And in places where I can use a pure
laser weld, I then have a clean joint of all the same metal, no real
seam line or visible joint once the weld is cleaned up, especially if
I’ve then annealed or stress relieve the weld so it’s the same
hardness as the surrounding metal. Such weld joints can often be
considerably stronger than a soldered joint as well, especially in
those cases where, were you to have soldered it, you’d have had to
use a medium or easy grade of solder. Even when welding silver
with a solder based filler wire, the joint can be considerably
stronger than a normal solder seam would be.

cheers
Peter


#9
i've been reading the thread about laser cutting with some interest
and thought i'd pass on some about a similar process
that i have used very successfully here in the uk - wire eroding -
you'll need to track down a company specialising in presicion
engineering, but it's a great technique using vector based files
from your pc that are then used to cut stacks of silver sheet so
that 5-10 pieces can be cut in one go depending on the thickness of
the silver. 

I looked into this some years ago for cutting titanium, but never
followed up on it. The place I talked to is called Adron, and the
process is called “wire EDM”. HTH

–Noel


#10

G’day Sally Would you mind mailing me the details of the company you
use in the U.K. please ? And if you could provide some idea of cost
and some pictures that’d be wonderful too Thanks a heap

Al Heywood


#11

Hi Dave.

Could you share a bit about the probable cost and whether this
method might be appropriate for less than huge runs?

Thanks
Pam Chott
Song of the Phoenix


#12

Hi Pam,

Could you share a bit about the probable cost and whether this
method might be appropriate for less than huge runs? 

It’s not clear what process (laser, waterjet or EDM) you’re asking
about.

However, the best bet is to check with a machine shop in your area.
If they don’t provide any of the services, they probably can refer
you to someone that does.

In my experience, many shops have ‘Set Up Charge" & additional
charge by the length of the cut & in some cases by the thickness of
the material. They usual rquire a .dxf file as input. Dxf files are
created by CAD & drawing software. Additionaly, if you provide the
material to be cut, they’ll need to know how you want the pieces
layed out to conserve material & whether & where you want them
’tabed’(small islands left between the cut piece & the sheet of
metal). If the pieces are small, not ‘tabbing’ them may result in
the cut pieces ending up in the bottom of a 4 ft. deep tank of water
& gunk. If the material being cut is precious metal, the cutter
keeps the material cut from the piece.

The nice thing about any of these processes is that once you have a
disk with a dxf file of the item, it can be reproduced in quantities
from 1 to thousands. If you have a quantity made at any one time the
setup fee is amortized over the number made & that keeps the per
piece cost in line. Depending on the size & complexity of a piece it
may be economical to cut just a single piece, however it’s probably
always more economical to cut multiple parts.

If you’re going to provide the precious metal for the cutter, it’s
probably a good idea to talk to him 1st about how the pieces will be
layed out on the sheet. The cutter will layout the cutting pattern
from the 1 dxf file. That way you may be able to reduce the amount
of scrap by buying sheet in a size that’ll leave the least scrap.
Water jet & laser cutters come in many sizes, some can only handle
small sheets, 2 ft x 3 ft, others can accomodate 7ft x 15 ft. The
only EDM machines I’ve encountered were non XY machines for small
work.

Dave