"cavelamb himself" wrote in message
m...
James Waldby wrote:

I got an email pointing at an interesting site about sculpting metal by a
method analogous to fast-prototyping-in-plastic machines, but in
stainless steel + bronze. See link to exone and description in the
second half of http://www.bathsheba.com/sculpt/process/ .
Links from exone refer to casting cores and molds direct from CAD.
(Of course, for many molds using a CNC machine shop might be better.)

Briefly, the bathsheba page says, "work up the design using CAD
software", then at exone "the design is laid down, one layer at a time,
in stainless-steel powder held in place by a laser-activated binder",
"the whole model is built up," "extra powder is shaken off,
the piece goes into an oven, where heat drives off the binder and fuses
the steel powder", producing a "porous steel part that's about 60%
dense", then the amazing part: "the stems are dipped in a crucible of
molten bronze, and capillary action causes the bronze to wick throughout
the piece" and "the end result is a composite metal that's fully dense,
with properties intermediate between steel and bronze. It can take a
polish or a patina, developing either rust (on the steel) or verdigris
(on the bronze)".

-jiw


Wow.

That dude did some serious warpage to the space-time continum.

Metal rapid-prototyping methods have been around for a while, including one
that's similar to this method, introduced by Extrude-Hone back around 2000
or so. It uses a CAD program (through STL output) to lay down the metal
powder in layers, with a polymer binder, which is then sintered together
into a 3D shape.

As for copper-alloy infiltration of porous PM parts, you may have some of
them in your shop. B&D and DeWalt were making the bevel drive gears for
their angle-head grinders that way at least as far back as 1997. And a lot
of automotive parts are made the same way.

This is not to knock this particular development, but it's not really a new
idea.

--
Ed Huntress