On Apr 24, 9:34*am, Ed Huntress wrote:
On Wed, 24 Apr 2013 07:28:47 -0700 (PDT), "Denis G."
wrote:
On Apr 23, 12:57*pm, Richard wrote:
On 4/24/2013 12:48 AM, Gunner Asch wrote:
On Tue, 23 Apr 2013 08:41:46 -0500,
wrote:
On 4/23/2013 7:57 PM, Gunner Asch wrote:
Fella brought over a gun part for a Marlin lever action..he was
missing a pin..so I made one up for him and installed it..and as I was
inspecting it..I noticed a rather serious crack starting to develop at
one end of the sintered metal part. * I fixed it by using my tig torch
and silver bearing flux..I packed the crack full of the heavy green
flux and zapped it with the tig..sealed it up well enough and I put a
slight layer over the area of the crack. After polishing it up with a
fine wire wheel, it looked good. But...is it?
How well does this sort of thing work with sintered metal parts?
Should I warn the guy to buy a new Widget? (Marlin just closed their
doors...so parts may become hard to find)
Any suggestions for other similar fixs with sintered metal parts?
Gunner
Which part?
Better link
http://www.urban-armory.com/diagrams/mar1894.gif
Part #8, 9, and 10 (and 11)
He was missing the #10 pin..and I turned, annealed, *replaced it and
peened it into place gently.
Gunner
Why do I get the impression that the rifle has been overstressed?
Repeatedly.
http://en.wikipedia.org/wiki/Metal_fatigue
Sintered metal parts start out with a bazillion "cracks" (voids) when
they go into the furnace (or hot isostatic press) and hopefully come
out with none. *Everything is controlled (temperature, pressure,
atmosphere) to get near net shape and avoid having to machine the
part. *Not to say that it can't be repaired, but I'd rather go to the
dentist.
Dollars to donuts, though, they ain't HIPping those gun parts. At
most, they're post-pressed and copper-infiltrated.
This part, though, looks like it wouldn't be practical to post-press.
And it's probably not infiltrated.
--
Ed Huntress
I was guessing that it was HIPped with the holes and final features
drilled and machined. (Certainly you can't pull apart the mold with
those sideways holes. The HIPped parts I've seen have copper powder
mixed in and with 30-50 ksi pressing you get pretty good part strength
and compaction and it's more state-of-the-art.
On the other hand, my experience is more with R&D and I don't know how
much throughput you'd get from HIPping vs. more conventional belt-
driven open air sintering furnaces, so maybe you're right.