Anyone with any luck turning down hard steel?
I have some punches for a punch press that I would like to turn down the shanks
from 1" to 9/16" to fit my press but all of them so far has been hard steel.
There should be a feed and speed one could use or grade of carbide to do this with.
Any suggestions are welcome.
Thanks
hard steel turning
Re: hard steel turning
If a file skips across it like glass, you have no chance of cutting it without grinding. That is a lot of grinding. Is it worth the cost of a wheel?
Punches are often a D2 tool steel. This takes hours in the decending heat of a controlled furnace to anneal back to a workable condition. Not really worth the power bill for scrap steel. Little else they would be good for.
I would not recommend hammering on them for any other purpose either. At the speed things go flying, with any luck, you won't be the bull's eye!
Other than that. They make a great tool for their intended use! [img]/ubb/images/graemlins/grin.gif"%20alt="[/img]
DC
Punches are often a D2 tool steel. This takes hours in the decending heat of a controlled furnace to anneal back to a workable condition. Not really worth the power bill for scrap steel. Little else they would be good for.
I would not recommend hammering on them for any other purpose either. At the speed things go flying, with any luck, you won't be the bull's eye!
Other than that. They make a great tool for their intended use! [img]/ubb/images/graemlins/grin.gif"%20alt="[/img]
DC
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tnta
Re: hard steel turning
I didnt realize they were made of d2 I thought it may be o-1 aand there would be
a type of HSS or grade of carbide that would turn it at a reduced speed?
I cant imagine having to grind it down that much , annealing would be out of the question also.
maybe someone has done this with good results?
a type of HSS or grade of carbide that would turn it at a reduced speed?
I cant imagine having to grind it down that much , annealing would be out of the question also.
maybe someone has done this with good results?
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cashirl
Re: hard steel turning
I was just reading on this topic on the Hardinge website earlier in the day. There are some examples listed where they were turning M2 and A2 tool steels with RC of 62. They seem to prefer ceramic or CBN tooling. Any way, here is a link to the page: Hardinge "hard turning" website
I would say that the most critical thing seems to be having a massive, rigid machine to do this sort of work.
-Shirl
I would say that the most critical thing seems to be having a massive, rigid machine to do this sort of work.
-Shirl
Re: hard steel turning
tnta,
The process of turning hardened steel is referred to as "hard turning". It's done on rigid CNC lathes with special inserts. Not a process for the average home shop guy.
Thor punch company tells me they make their punches from pre-heat treated blanks and "hard turn" the business end to size (round ones, that is).
Back a few years one of the used tooling houses in Los Angeles had a variety of large HSS end mills with the shanks turned down. The 2" diameter mills with the shanks turned down to 1" got my attention. Now, that's some nasty material to turn, makes your punch shanks seem like butter in comparison.
The process of turning hardened steel is referred to as "hard turning". It's done on rigid CNC lathes with special inserts. Not a process for the average home shop guy.
Thor punch company tells me they make their punches from pre-heat treated blanks and "hard turn" the business end to size (round ones, that is).
Back a few years one of the used tooling houses in Los Angeles had a variety of large HSS end mills with the shanks turned down. The 2" diameter mills with the shanks turned down to 1" got my attention. Now, that's some nasty material to turn, makes your punch shanks seem like butter in comparison.
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tnta
Re: hard steel turning
Yea I am thinking my punches are maybe a 62 hardness and made of M2 or A2
but regular carbide is just messing them up.
You know they make these things hard , they cant be the hardest on the planet so I am thinking there is an insert that is harder than these. Plus I have to do them dry I have no coolant set up.
Anyone out there care to take and stab at turning some of these down for me.
Probably the biggest is 1 1/2 " o.d . and needs turned down to 9/16 "
.a few are at 1" and needs to be 9/16 "
but regular carbide is just messing them up.
You know they make these things hard , they cant be the hardest on the planet so I am thinking there is an insert that is harder than these. Plus I have to do them dry I have no coolant set up.
Anyone out there care to take and stab at turning some of these down for me.
Probably the biggest is 1 1/2 " o.d . and needs turned down to 9/16 "
.a few are at 1" and needs to be 9/16 "
Re: hard steel turning
Hard turning is done on known materials and typically up to an .008 finish pass on materials capable of local heat treat by the heat generated ahead of the cut running dry with no coolant. High surface speeds will create the heat and PCBN inserts do the work. Roughing is limited to .02 and cutter breakdown is rapid.
If you know the manufacturer, material and replacement cost of these punches. Compare that to the cost of several PCBN inserts and the time to turn off that amount of material. Handing it off to a job shop adds even more to the cost.
There may be some level of justification on your end. At first glance, it just looks like more trouble than it is worth.
DC
If you know the manufacturer, material and replacement cost of these punches. Compare that to the cost of several PCBN inserts and the time to turn off that amount of material. Handing it off to a job shop adds even more to the cost.
There may be some level of justification on your end. At first glance, it just looks like more trouble than it is worth.
DC
Re: hard steel turning
D R
With reference to large HSS milling cutter shanks being turned down, I am only a newbie to all metalworking so I cant fully quantify my experince:- however out of interest I picked up a brand new "Osbourne" 2" end mill with 11/4" shank which I wanted to put in a 1" collet. Since it had centres at both ends i put it up between centres on my old Hardinge HLV-B and then used bog standard diamond shaped insert. when I ran it at "normal" feeds and speeds it cut but the insert crumbled after a short while and the surface finish was horrible, when I increased the feed, DOC and speed it suddenly started cutting like a dream, nice little C's turning blue as they sort of drip at high speed of the insert leaving an absolute mirror finish. It was probably running at about 700rpm, .05" doc, feed was about 25% round the dial and one insert took the whole lot off. So I guess its worth a try.
Cheers Nigel
With reference to large HSS milling cutter shanks being turned down, I am only a newbie to all metalworking so I cant fully quantify my experince:- however out of interest I picked up a brand new "Osbourne" 2" end mill with 11/4" shank which I wanted to put in a 1" collet. Since it had centres at both ends i put it up between centres on my old Hardinge HLV-B and then used bog standard diamond shaped insert. when I ran it at "normal" feeds and speeds it cut but the insert crumbled after a short while and the surface finish was horrible, when I increased the feed, DOC and speed it suddenly started cutting like a dream, nice little C's turning blue as they sort of drip at high speed of the insert leaving an absolute mirror finish. It was probably running at about 700rpm, .05" doc, feed was about 25% round the dial and one insert took the whole lot off. So I guess its worth a try.
Cheers Nigel
Re: hard steel turning
"I am thinking my punches are maybe a 62 hardness and made of M2 or A2
but regular carbide is just messing them up."
Most punches, like Roper-Whitney sheet metal type, are much softer than Rc 62. The punches used in CNC punching machines tend to be quite hard though.
BTW, I've made punches out of hardened dowel pins. Use pins as close to the hole diameter as possible since dowel pins are softer towards the center.
but regular carbide is just messing them up."
Most punches, like Roper-Whitney sheet metal type, are much softer than Rc 62. The punches used in CNC punching machines tend to be quite hard though.
BTW, I've made punches out of hardened dowel pins. Use pins as close to the hole diameter as possible since dowel pins are softer towards the center.
Re: hard steel turning
I have hard turned in engine lathes before. I use the black ceramic inserts. The 80 degree diamond shaped negative inserts (CNMG) are what I use the most. Generaly if you can hold a tolerance on regular work then you can hard turn. I run at 400 surface feet and .001" feed rate and watch the sparks fly.