On Wed, 1 May 2013 11:03:41 -0700, "anorton"
wrote:
"Ed Huntress" wrote in message
.. .
On Wed, 1 May 2013 10:37:51 -0700, "PrecisionmachinisT"
wrote:
"Ed Huntress" wrote in message
...
On Wed, 1 May 2013 05:45:38 -0700 (PDT),
wrote:
On Friday, May 30, 1997 12:00:00 AM UTC-7, wrote:
I hear terms like "Oilite", "Sintered Bronze", and
"Oil-Impregnated Bronze SAE-841" used for bronze bearings.
Are these all the same thing, or slightly different alloys?
In this context, what does "Sintered" mean?
What would you expect for a bearing of this sort?
Does it need constant, occasional, or no lubrication?
What would you expect for life?
When would you use this as preferred to cast bronze
or some other bushing?
Thanks for your help!
--
Bob Neidorff
-------------------==== Posted via Deja News
====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
Sintered Bronze bushes are usually used in every machine part..
http://www.surajcomponents.com/self-...d-bearing.html
I didn't see Bob's original on this,
It was originally posted in 1997, and resurrected by a spammer, probably
Chinese.
but here are some answers to his
questions:
1) Yes, they are all the same thing. Any of them can be various
alloys, including Oilite, but most are made of a plain bronze or
bearing bronze, the latter for high loads. They aren't exactly the
same alloys used for plain bushings but they're close.
2) Sintered means they are heated to diffusion temperature (below
actual melting) to bond the particles together. The particles are
bronze powder. The powder is pressed in a die and then sintered in a
furnace. They don't press the powder to full density because they want
it to remain porous, to hold oil, which they inject into the bearings
under pressure after sintering.
A pressure cooker would probably do it.
3) A sintered bearing, if the right thing for the application, can
last for years in intermittant use. Or weeks, if it's not the right
thing.
Examples: I have a blender with a sintered bronze bearing that is 40
years old. The oil in it dried up after about 10 years, and it started
to bind. Now I put one drop of light oil on it every third or fourth
time I use it, and it's still going strong after an additional 30
years.
Another: The burner-blower motor on my gas-fired furnace has sintered
bearings front and back. It is 30 years old. The front bearing dried
out and seized after 12 years. I took it apart, polished the armature
shaft on my lathe, and re-assembled it. I put two drops of
lathe-spindle oil (for plain bronze bearings; it's South Bend oil) on
the front bearing and one on the rear bearing every Ocotober. It
usually lasts until February, when I apply more oil. I'm now using
Mobil 1, 0W-20. I've noticed that it lasts for the whole heating
season.
You'll never fully replace the pressure-injected oil of a new bearing
this way, in terms of how much oil you can get into it, but such
bearings actually seem to run better with the oil dripped on
externally. That stands to reason because the injected oil only gets
to the bearing surface by capillary action, and it must be a very
light oiling that the bearing gets in that way.
Good info nonetheless.
Jeez, though...spending the time to write that when it was posted in
1997...'makes one kind of cynical about every *trying* to get
something going on metalworking, ya' know?
Oh well, back to the Constitution and explaining match rifles versus
service rifles. g
--
Ed Huntress
Instead of a pressure cooker, I wonder if one way to re-impregnate oil into
a sintered bushing might be to soak it in oil and pull a vacuum on it. The
air will go out and then the oil will be pushed back in after
re-pressurizing. I have used small vacuum containers and a hand pump for
de-gassing epoxy, and they sell something similar for food storage.
It may be. I read about how they're made in....uh....around 1978, when
I was working for _American Machinist_. My memory doesn't do well on
details that far back.
But IIRC, they *first* pull a moderate vacuum, and then fill the
bearing with pressure. If they don't pull some vacuum first the oil
can be forced out after the pressure is released.
I think. Or they push from one side and leave the other side open to
the atmosphere. Or maybe they do one or the other, depending on the
bearing configuration. My memory on this one is a mess, between my
original guesses and what I learned when studying powder metallurgy.
Again, that was a long time ago for me.
--
Ed Huntress