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Ultrasonic milling for carving bones


#1

I am trying to find regarding a new high-tech procedure
known as ‘ultrasonic milling’ which jewellers use for carving gem
stone (or jade). I am interested in finding new and improved ways
for carving bone.


#2
I am trying to find regarding a new high-tech
procedure known as 'ultrasonic milling' which jewellers use for
carving gem stone (or jade). I am interested in finding new and
improved ways for carving bone. 

I don’t know that I’d call this all that new. I’ve seen German
ultrasonically carved (milled, if you like) Cameos for sale for most
of my career, available since at least the mid 70s, maybe earlier.
The equipment is essentially similar to an ultrasonic drill (commonly
used to drill holes in gemstone beads), except the cutting tool is a
shaped tool that, as it’s lowered onto the stone, grinds a matching
shape into the stone. The process works best with hard brittle
materials, so I’m not so sure how well it would work with bone. And
last I saw such equipment for sale, it wasn’t cheap. cutting tools
have to be made for each shape you’ll be producing. In a sense, the
process is somewhat similar to EDM machining, where electric spark
discharge between an electrode (the cutting tool) and the workpiece
produces erosion on the workpiece so it’s shape ends up matching the
cutting tool. With ultrasonic milling, ultrasonic energy along with
an abrasive slurry, does the work rather than electric discharge.

If, rather than high production of multiples of a single design,
you’re interested in efficient carving of unique one at a time work,
you might look into the very high speed air turbine handpieces. These
are much like what your dentist uses to drill on your teeth. At
extremely high speeds, carbide and diamond tools cut bone like butter
with very high levels of control.

Peter


#3
ultrasonic milling' which jewellers use for carving gem stone (or
jade). 

Well, sorry, Jayson…Ultrasonic milling and drilling is far from
new, first off. You see those really crisp agate cameos that are
comparatively cheap in Rio Grande, among others. Those are
ultrasonically milled, as are computer chips and all manner of
things.

The other part is that the whole system is tailored to hard
materials - ~really~ hard materials that are probably also brittle.
I don’t want to go so far as to say that it won’t work at all on
bone - if it works, it works.

But there’s a good chance it won’t, and even if it does it will be
greatly slower than a good belt sander for 1/1000 the cost. Yes, they
are seriously cool - I even tried to build one once, without success.
Whenever you get into hardstone, that’s the time to think about
it…


#4
I am trying to find regarding a new high-tech
procedure known as 'ultrasonic milling' which jewellers use for
carving gem stone (or jade). I am interested in finding new and
improved ways for carving bone. 

Ultrasonic milling is a great way to cut hard but you
don’t really need it for bone. Have you tried ordinary rotary-tool
CNC milling for that? I have; and in my opinion bone cuts quite well
with ordinary carbide tooling.

But I’m interested in the ultrasonic method as well, for harder
materials. I wonder if anybody makes an ultrasonic milling head,
that could be mounted on a standard CNC mill, much like laser scanner
heads are. If anyone out there has experience with ultrasonic
milling, please speak up! For one thing, I’m curious about the sort
of surface that’s produced by the process. Does an onyx cameo or
whatever come out perfectly without further treatment, is this just a
rough carving that will need many successive grits to finish, or does
the truth lie somewhere in between?

Andrew Werby
www.computersculpture.com


#5
But I'm interested in the ultrasonic method as well, for harder
materials. I wonder if anybody makes an ultrasonic milling head,
that could be mounted on a standard CNC mill, much like laser
scanner heads are. 

I believe you could but I am not certain what advantage you would
get from it. They can be mounted on a vertical mill. The cutting
action is only really on the face of the tooling. The transducer
moves the tool in the Z axis and the grit slurry pumped between the
tool and the object to cut is what actually does the cutting.

If anyone out there has experience with ultrasonic milling, please
speak up! For one thing, I'm curious about the sort of surface
that's produced by the process. Does an onyx cameo or whatever come
out perfectly without further treatment, is this just a rough
carving that will need many successive grits to finish, or does the
truth lie somewhere in between? 

The surface finish depends on the material being cut and the
fineness of the grit slurry. most everything I have seen has had
something of a very fine matte finish I am not certain that a
polished surface can be produced with it. But for more information
contact Sonic Mill ( http://www.ganoksin.com/gnkurl/18f ) they can
fill you in on its capabilities. They offer contract machining and
sell the machines.

James Binnion
James Binnion Metal Arts


#6
I wonder if anybody makes an ultrasonic milling head, that could be
mounted on a standard CNC mill, much like laser scanner heads are.
If anyone out there has experience with ultrasonic milling, please
speak up! 

Hi, Andrew. Define experience… Maybe, maybe not. Maybe I’m the
only one here who’s actually used an ultrasonic drill - maybe. And
I’ve been intrigued and followed it fairly casually ever since.
First off, there are milling machines and milling heads out there,
yes. Of course, that also includes a controller/ultrasonic circuit.
There are actually two versions, in general. Pure ultrasonic and
rotary ultrasonics, which have pretty obvious differences in
application. The two vendors I know of- I think they are just about
it, for the business - are sonicmill:
http://www.ganoksin.com/gnkurl/18f and DMG Sauer:
http://www.ganoksin.com/gnkurl/1by

It’s no coincidence that Sonicmill is in Albuquerque, as it’s a
subsidiary of Rio Grande. Also, a Google of "ultrasonic milling"
brought up a couple if interesting papers…

As for finishing - those cameos come straight off the machines. If
you look close, you’ll see they are somewhat of a buff finish. It’s
standard lapidary abrasives: You can use 100 grit and cut this in
five minutes, but it will take 12 hours to finish it, or we can use
1000 grit (whatever) with ultrasonics, cut it in an hour and it’s out
the door. Penny wise or pound foolish, as the saying goes. Of
course, none of this is cheap…

For the uninitiated - you get yourself an ultrasonic milling
machine, which is MUCH higher power than an ultraonic drill - there
is a “cone of power” in such things. A drill’s cone is about 1mm -
outside of that it doesn’t cut. A mill might have 3 or 4 inches -
mucho power. You get yerself a piece of steel - I don’t know what
they use for dies, actually - and cut a wonderful horse into it in
negative relief. Mount it in the machine, put a slab under it, put
grit between the two, turn it on and the machine cuts the horse into
the slab, exactly and precisely. And the dies last longer than you
might think, because it’s not the die that cuts, it’s the
grit… Seriously cool stuff.


#7

Thanks, James and John, for the informative replies. I didn’t really
understand how these tools work, but it’s clearer now. Making a
cameo or whatever from a detailed die, like the EDM process for
metal, does sound like a good way to go for producing multiple
identical parts. But I still wonder if the rotary ultrasonic process,
which the SonicMill site recommends for drilling operations, can be
used with a ball-nosed tool for one-off 3D carvings in hard stone,
similar to normal CNC milling in wax. Maybe I’ll ask them and report
back. If they are a subsidiary of Rio Grande, they must be used to
off-the-wall questions from non-engineers…

Andrew Werby
computersculpture.com


#8

I have some experience with ultrasonic cutting. The factory that I worked at produce some of the models,all of the molds and the production for the Erté “Art to Wear” project for Circle Fine Art. Many of the pieces used ultrasonic cut stones. Just the molded themselves are difficult. Either “cookie cut” or 3D. After the waxes are pulled they’re cast in a stainless steel alloy using the same investment and casting as platinum - over 3,000 F. We were doing this at the same time Eddie Bell and Clyde Treadwell were developing “Sonic Mill” - used extensively in Germany now for decades. Unless you plan on spending a lot of money up front it wouldn’t be for you. The previous answers were correct. Bone is way tool soft and would not cut at all. Jade is polycrystalline and is very tough and resilient - it could be cookie cut with several tools and a lot of time. All in all an expensive process more suited to production pieces and definitely not a “do it yourself” project. Hand carving would be more appropriate for bone or Jade. This may be redundant but I hope it gives you a better understanding of the process.