Thread: milling problem 17-4 PH stainless

Hi All:
Here's why it's better to pre harden 17-4 PH stainless instead of milling it in the solution annealed condition.
This is the second time I've had this problem in 20 parts so far.

I broke my own vows and didn't listen to my gut because I was under pressure from the customer to begin cutting.
Some times we're just our own worst enemies aren't we?

Curse curse curse!!
Cheers

Marcus
Implant Mechanix – Design & Innovation - home
Vancouver Wire EDM -- Wire EDM Machining

Been done, broke that, burned the t-shirt.

Geez, now you've done it Zahnrad: there's coffee all over the keyboard and the monitor from laughing so hard.
Cheers

Marcus
Implant Mechanix – Design & Innovation - home
www.vancouverwireedm.com

My pleasure, old Chum. Anything to help.

were you slotting or what?

Originally Posted by John Welden

were you slotting or what?

I'm gonna wager that was the last straw of a short run that ended right after a ramping entry.

PS - By the by, Marcus, I really do sympathize and feel your pain.
It's so damn easy to do ( acquiesce for a hounding customer ) but like I always say - "Always go with your gut. Your gut never lies."
We get so hurried at times, but in all reality - it's just a few hours in the box. Eh?

98% of the Surgical Instrument prototypes I make are made from 17-4. It's gotten to the point that some times I wonder why they even SELL it in the annealed condition. It's just so damn problematic. As you're painfully aware, it's SO much nicer in the hardened state and if something came up that absolutely just HAS to be in the annealed state it's just as easy to go the other direction with it. That said, I can only think of ONE time that I had to anneal a part...

I've machined a butt ton of 17-4, but 99.8% has been H900.

Hi All:
Actually the first one was plunging with 1/4 the cutter diameter
The second one was profiling 0.010" radial engagement and 0.050 DOC
The cutter is a 3/16 TiAlN coated 4 flute carbide stubby.
With this soft gummy shit, it will whistle along nice and quiet until all of a sudden it won't for a second or so.
You can hear the metal piling up on the flutes; it sounds harsher and harsher and then it breaks through the other side and all is good for a while again except the cutter she don't sound quite so nice no more.
Then you hit another gummy spot and the noise gets a little worse.
If you look at the cutter under the scope it's starting to get a bit ratty, but it's only been in the cut for 10 minutes or so, so you go; Ahh, what the Hell, let's see how long she lasts.
You touch up the corners of the endmill with a diamond disc, shove 'er back in the machine and push the green button.
All goes OK for another half an hour; you're starting to get complacent and thinking about going for lunch then all of a sudden GRAAUNCHHH: you have just blobulated (technical term for instant severe BUE).
Now the cutter is truly toast (good thing we're still just roughing) so in goes a new cutter and the cycle begins anew.

Zahnrad Kopf, I agree 100%...why oh why can I only buy solution annealed bars, and why was I so stupid not to chop them up and send them to heat treat before the pressure came on to get them made?
It's my own damn fault for letting my customers dictate my schedule again.
Now I've got some emergency D2 that came out of the oven 10 Rockwell points too soft; anyone here re-cooked D2 and had it work out or will I need to nitride the parts after they're made or just toss the blocks and begin again?

Some days this is all just too much FUN!!
However, we can all console ourselves with the timeless truth that making stuff for a living, even on a shitty day, is still miles better than doing dentistry for a living, even on a good day.
Trust me, I KNOW this!!
Cheers

Marcus
Implant Mechanix – Design & Innovation - home
Vancouver Wire EDM -- Wire EDM Machining

Originally Posted by implmex

All goes OK for another half an hour; you're starting to get complacent and thinking about going for lunch then all of a sudden GRAAUNCHHH: you have just blobulated (technical term for instant severe BUE).

Ha ha ha ha ha ha ! That's a wonderfully accurate description of my own experiences as well.

Originally Posted by implmex

Zahnrad Kopf, I agree 100%...why oh why can I only buy solution annealed bars, and why was I so stupid not to chop them up and send them to heat treat before the pressure came on to get them made? It's my own damn fault for letting my customers dictate my schedule again.

Ahhhhhh... Tha' 'esplains it, Lucy... I didn't know you sent it out. Yeah, that makes it a different ball game. We do our own heat treating. So when I want/need to harden our 17-4, it's a few hours in the EZ-Bake and Bob's your uncle.

Originally Posted by implmex

Now I've got some emergency D2 that came out of the oven 10 Rockwell points too soft; anyone here re-cooked D2 and had it work out or will I need to nitride the parts after they're made or just toss the blocks and begin again?

Yeah, remember those pieces I showed you a few weeks back? Had to re-cook them as well. I do it from time to time when necessary. It'll be fine.

Originally Posted by implmex

However, we can all console ourselves with the timeless truth that making stuff for a living, even on a shitty day, is still miles better than doing dentistry for a living, even on a good day. Trust me, I KNOW this!!

Oh, you go on, so... You act like it's pulling teeth or something. Oh... wait...

Originally Posted by implmex

You touch up the corners of the endmill with a diamond disc, shove 'er back in the machine and push the green button.

I have had better luck using a 2 flute when it is annealed.
But now I just get it pre hardened.

Originally Posted by jmilless

I have had better luck using a 2 flute when it is annealed.
But now I just get it pre hardened.

I do the same thing only I use 3 flute cutters, and run coolant an slower.

I almost always get it hardened as I can generally get it same day if I drop it off in the morning.

Originally Posted by MK Proto

I almost always get it hardened as I can generally get it same day if I drop it off in the morning.

If there is no other reason in the world to get your own heat treat oven, PH grades are that reason.

We USED to do the other stuff, but its a pain in the ass. Real high temps, quench, wait for the damn oven to cool, temper, stinky oil,
foil packs, argon... Sucks.

PH grades, just toss her in there and take a nap for 4 hours. Unless its an H900 then its an hour. Even if its a pottery kiln...

Our oven pays for itself over and over and over and over again, just on PH grades. Handy for annealing aluminum and aluminum rivets also.

Originally Posted by Bobw

If there is no other reason in the world to get your own heat treat oven, PH grades are that reason.
We USED to do the other stuff, but its a pain in the ass. Real high temps, quench, wait for the damn oven to cool, temper, stinky oil,
foil packs, argon... Sucks.
PH grades, just toss her in there and take a nap for 4 hours. Unless its an H900 then its an hour. Even if its a pottery kiln...
Our oven pays for itself over and over and over and over again, just on PH grades. Handy for annealing aluminum and aluminum rivets also.

I don't know, Bob. I am cooking something almost every single day and it really doesn't bother me. At all. I'm just happy not to be dependent on someone else. Plus, I'm a bit picky about how I want things done. Seems like no one else gives flying rat's ass when you send them a 6" x 12" x .500" plate with multiple parts nested into it, fully machined, only needing WEDM once it's heat treated. So you get it back like it came from the Pringles factory and looking great if it were a potato chip. I do it, and it barely moves .005", corner to corner.

But yes, if only for the PH stuff alone, they're definitely worth it.

What am I doing wrong? I never have issues like that with 17-4.

Originally Posted by charlie gary

What am I doing wrong? I never have issues like that with 17-4.

You're a rock star.

Originally Posted by Zahnrad Kopf

You're a rock star.

Oh man, now my secret's out.....

Maybe it's because I buy cheap soluble oil for coolant and keep it mixed rich.

I guess I've always liked machining 17-4 PH-A. Beats the hell out of 4142 (IMHO) come chip time. Yeah, the milling inserts don't live as long as I'd like them to, and the same with turning and threading inserts, but this isn't 12L14, either.

The only complaint from me is cleaning out the chip pan before machining the stuff so that the 30 cents per pound scrap for the chips can be obtained.

Originally Posted by charlie gary

What am I doing wrong? I never have issues like that with 17-4.

Fairly certain its near identical to 15-5ph-a.. of which we fill up numerous barrels each week. Same deal, perhaps it could be better, but have never given it a second thought.

The only complaint from me is cleaning out the chip pan before machining the stuff so that the 30 cents per pound scrap for the chips can be obtained.

Wait, what? you get 30c/lb for 17-4? Haven't found anyone who will pay more than scrap steel price for our 15-5. Perhaps need to do more investigating.

Originally Posted by John Welden

I've machined a butt ton of 17-4, but 99.8% has been H900.

Can you tell me the difference between H900 and H1075?
Which one is easier to machine,and is there a big difference? I have a bunch of H1075 blocks coming.
Thanks!