Bobw
Diamond
- Joined
- Feb 8, 2005
- Location
- Hatch, NM Chile capital of the WORLD
So we get this giant job and part of it is 36 pieces, 15" long, 3-5/16 wide, 5/8 thick, out of 17-4. Stock is supposed to be 17-4 5/8 thick, 4.5 wide supplied by the customer. It came in waterjet to 4.6 wide out of 3/4 plate, no biggie, a few extra minute. But its 17-7.
Figure no biggie on the 17-7 vs 17-4. Boy was I wrong.
They said they couldn't find 17-4 in that thickness so they got 17-7.
I start running it like its a condition A 17-4, with the proper inserts. Wet, 225 sfm. Nope, 200 sfm, nope, 150 sfm nope, 110 sfm, nope, maybe 5 minutes of life. WTF, I can get an hour plus on 13-8 with 130sfm with these inserts.
So, OK, the PH grades usually machine better heat treated, this is going to an H1050. We can do that in 4 batches and certify it. The customer doesn't like that and will only pay for 2 batches. We dig a bit further and realize that this 17-7 is in a condition A and is only a "semi" PH. It needs to be cold worked to a condition C to be able to be hardened like a ph grade or needs some extra heat treating to be able to be heat treated like a ph grade.
In this case it needs 1450 at 90 minutes and then within an hour brought to 60 +10 for 30 minutes, or brought to 1750 and then to -100. Then it can be normal PH grade heat treated.
I'm glad they didn't like our HT price because I think they are going to eat it on this one.
So, when I get this crap back at an H1050, at about 36C, is she going to behave. Right now she's at a ConditionA, she's at about 5c(85B)[sticky gummy garbage].
Googling I've found a machinability rating of 75% of 12??. I've also been told that 17-4 and 13-8 are the same, thats like saying that A286 and aluminum are the same and titanium and nylon are the same.
Anybody have any experience with this crap? This was quoted as 17-4, I'm willing to give up a little, but not much.
Figure no biggie on the 17-7 vs 17-4. Boy was I wrong.
They said they couldn't find 17-4 in that thickness so they got 17-7.
I start running it like its a condition A 17-4, with the proper inserts. Wet, 225 sfm. Nope, 200 sfm, nope, 150 sfm nope, 110 sfm, nope, maybe 5 minutes of life. WTF, I can get an hour plus on 13-8 with 130sfm with these inserts.
So, OK, the PH grades usually machine better heat treated, this is going to an H1050. We can do that in 4 batches and certify it. The customer doesn't like that and will only pay for 2 batches. We dig a bit further and realize that this 17-7 is in a condition A and is only a "semi" PH. It needs to be cold worked to a condition C to be able to be hardened like a ph grade or needs some extra heat treating to be able to be heat treated like a ph grade.
In this case it needs 1450 at 90 minutes and then within an hour brought to 60 +10 for 30 minutes, or brought to 1750 and then to -100. Then it can be normal PH grade heat treated.
I'm glad they didn't like our HT price because I think they are going to eat it on this one.
So, when I get this crap back at an H1050, at about 36C, is she going to behave. Right now she's at a ConditionA, she's at about 5c(85B)[sticky gummy garbage].
Googling I've found a machinability rating of 75% of 12??. I've also been told that 17-4 and 13-8 are the same, thats like saying that A286 and aluminum are the same and titanium and nylon are the same.
Anybody have any experience with this crap? This was quoted as 17-4, I'm willing to give up a little, but not much.