Harold & Susan Vordos wrote in
rec.crafts.metalworking on Tue, 03 May 2011 06:02:57 GMT:
"dan" wrote in message
...
wrote in
rec.crafts.metalworking on Mon, 2 May 2011 18:40:16 +0000 (UTC):
So I'm starting a job machining 174-ph HH-1150. I've found lotsa info
on condition H1150 but not much on HH1150. I know that the HH1150 is
heat treated twice at 1150 degrees F and that it's hardness is 28RC.
It is softer than the annealed condition. What I have not been able to
find out about is whether it will be gummy and tend to stick to the
cutting tool like 316SS or 304SS. It's been several years since I
machined any 17-4 (12 years maybe?) and I don't remember the condition
it came in. I don't think it was HH1150. It seems like HH1150 is now
more common than H1150 because it is mostly backwards compatible with
H1150. But how long this has been the case I don't know.
Thanks,
Eric
I've turned a fair bit on a swiss lathe. It is gummy, and the chips
don't like to break. It will work harden if you look at it funny.
Feed at .0015"/rev MINIMUM. Don't get it hot, keep coolant on the
cut, don't tickle it. Get into the cut and keep cutting. Lower
speed(rpm) higher feed(ipr). I don't know what SFM I run it at, but
I'm usually working with .250" to .625" stock and start off a 1500
RPM. If you find the right conditions, your drills and other tools
will last as long as if you were cutting 303ss or 304ss.
A light clean up pass(.010") will give a good finish.
--
Dan H.
northshore MA.
I question our experience if you find a comparison between 303 and 304. They
clearly do NOT machine the same way.
I didn't intend to imply that they similar to machine.
304 can be a real PITA. It is not a
free machining stainless, while 303 is.
Harold
Yes, I know the difference between 304 and 303. I But when you get
the right speeds and feeds for each one, your tools will last much
longer.
If you are only making a few parts you might not notice. But when you
make thousands, and keep notes of when you have to change inserts, you
can home in on the best speed and feed rate for each alloy and job,
and the tool life goes up quite a bit. And you have the added benefit
of being able to change out the insert before it really fails.
What I was trying to get across is that 17-4ph isn't any more of a
mystery to machine than 304(tough) or 303(easy). You just need to
know the right speeds and feeds for the cutting conditions.
--
Dan H.
northshore MA.