"Dave__67" wrote in message
...
On Jul 6, 9:23 pm, "Phil Kangas" wrote:
I never thought I'd see the day when something
like this could be done! Amazing, to me anyway...
phil k.

http://www.wimp.com/functionaltools/

Someday this'll be done with powdered metal and it'll be sintered
afterwords.

It already is. Extrude Hone showed such a machine and system at IMTS 2000. I
may still have a photo of one of the parts, which I ran in my IMTS coverage
in _Machining_ magazine.

It's a takeoff on an injection-molding and sintering technique developed by
Rocketdyne back around 1979 or so, for making little, integral rocket
combustion chambers and nozzles. They mix powered metal with a plastic
binder, and then sinter the workpiece to evaporate the plastic and to form a
standard, sintered diffusion bond among the metal powder particles. They get
pretty good density.


Won't be as strong as forged or maybe even cast (unless they can work
in a compressing step), but it'll be a lot stronger.

You can post-sinter-forge PM parts, if the shape lends itself to it (car
makers do this with engine connecting rods), but there are two other things
you can do to get near-100% density. One is to use a mix of metals that
coalesces into a compact mass when it's sintered. These mixtures are secrets
in the industry.

The other is to infiltrate the sintered part with molten metal. The bevel
gears on DeWalt angle-head grinders are made that way, PM-pressing the gears
from a steel alloy, sintering, and then infiltrating with copper to get 100%
density. It's very strong and very tough, and the accuracy of the bore is
something like +/- 0.001". We machined these at Wasino, to prove the process
for them, and they turn the bores to + 50 microinches, -0 with
cubic-boron-nitride tools. Dry.

I wrote a cover story on that process for _Tooling & Production_, back
around 1999 or 2000. These processes are not new.

--
Ed Huntress

Am I the only guy that noticed he was turning the wrench the wrong way
(there, that'll stir things up)?


Dave