Work hardening, on purpose?

Hi all,
Well, you folks are getting the abridged version. I've pared it down
quite a bit from what went to rec.crafts.metalworking. Be thankful.
Man, I didn't realize just how long that thing was until I saw it come
back to me in my news reader. It's still too long, though. Sorry.
Does anyone ever intentionally use a work hardening material, such as so
much of the stainless family, and actually adopt processes to work-harden
it, on purpose, for machine tooling? I'm interested in this aspect for
wear resistance. I'm guessing this would just be a case-harden, but for
wear resistance, it seems like that's really all I'd need, eh? Seems like
this would be a lot less expensive a process than heat treatment, but
then again, what do I know? That's why I'm here asking you folks...
The application here is a quick-change tool post (i.e. for a metal
lathe). I think I've come up with a design that will be *MUCH* cheaper
to manufacture than what I see being made today. It's starting to look
like I just might be able to produce an exceptional quality product that
I think I may be able to sell for even less money than the cheapest of
cheap knock-offs.
That's why I'm posting here: I want to produce such a good tool that I
would be comfortable offering one of those no questions asked ``forever
warranties'' found in a few of the better manufacturers, but still keep
the tool price down near the cheapo knockoff level. The price savings,
I believe would come from it being so incredibly simple to build, not
from cheating customers and/or employees like the weasels like to do.
Honestly, I don't know if I'll be able to achieve that goal or not, but
that's the goal for which I am aiming. I think my design goes a long way
to keeping the price to a minimum without sacrificing quality to do it,
but the material selection, I think, is going to be critical.
Anyway, here are the main things I'm concerned about:
1) Strength: I don't want it to deform even under constant, heavy use.
2) Wear resistance: For obvious reasons.
3) Corrosion resistance: Even in nasty environments (i.e. coolant).
4) Processing cost: For obvious reasons.
Cost of material, I'm not really all that concerned about, I don't think.
From what I can tell, that looks like it'll probably be just about the
least of my expenses in this endeavor. I'm far more worried about how
much it's going to cost to process whatever material I choose.
Strength, well, actually I suspect that's one of the least of the above
worries. I suspect pretty much any steel of any reasonable quality
will probably be strong enough. Most of the strength will come from
the mass of this thing, I suspect, not so much from the steel selection,
but it is important enough to at least include it on my list of worries.
Now, some suggestions I've gotten are for either Ni-Cr-Mo or at least
Cr-Mo types (4340 or 4140, and such like so). From what I've read about
these, they both sound like wonderful stuff, but some disadvantages
I see there are that in order to really get the most out of them,
they'd need to be heat-treated. That just seems way too costly to me.
I know I can get these metals in various conditions, but if I get it soft
enough to machine at all, even if only with great difficulty, it seems
like that's going to be soft enough to allow more wear than I'd like.
Further, I do believe both of these are somewhat corrosion resistant,
but are they enough so that one could expect these things to stand up
to coolant and time?
So, what about a good stainless? Good corrosion resistance, so it
should stand up to coolant well enough. If I work harden it with an
eleventy buhzillion ton rolly-squeezy-mashy machine as my final forming
process, shouldn't that give me a good hard face on my sliding surfaces,
and shouldn't that give me good wear resistance?
If this actually works (you tell me, I've obviously got no clue), I can
see some advantages:
1) I'd get to build myself a really cool rolly-squeezy-mashy machine, and
I'd get to watch it go.
2) Corrosion resistance.
3) I'd get to build myself a really cool rolly-squeezy-mashy machine, and
I'd get to watch it go.
4) Hardening without heat treatment. It would *HAVE* to be cheaper to
build and run a specialized rolly-squeezy-mashy machine than a specialized
heat-treat facility (I think).
5) I'd get to build myself a really cool rolly-squeezy-mashy machine, and
I'd get to watch it go.
6) Should be pretty easy to get a good finish on those sliding surfaces
if they're formed, as opposed to cut.
7) I'd get to build myself a really cool rolly-squeezy-mashy machine, and
I'd get to watch it go.
Yeah, OK, so it's not perfect, either I'm sure. For starters, I have
no idea how hard I'd be able to get my sliding surfaces, or for that
matter, just how well that hardness will translate into wear resistance.
I know there's a correlation between hardness and wear resistance, but
I don't know if this process would really be good enough in that regard.
For that matter, I don't even know if it would necessarily be any better
than what I could get from some, say, condition medium 4340 without any
post-machining heat-treat.
I realize that my rolly-squeezy-mashy machine would probably not be the
end of the processing. Presumably, I'm not going to get the exact right
shape coming out of that thing, so I'd probably have to grind some after
that, too.
What about internal stresses? Am I going to be building a bunch of
time-bombs of returned parts waiting to go off?
Has anyone out there heard of doing such a thing successfully? I've been
scrubbing the Net, and all the references I find say something like
``unfortunately this material work-hardens...'' as if there is no possible
upside to that. Is that really so?
Is this just yet another bad idea grunted from my brain which needs to
be abandoned like so many of the other steaming mounds of brain goo I've
grunted out over the years?
Anyone wanna offer support for some other materials and/or methods? Am
I better off just sticking with something like 4340 condition medium, or
4140 pre-hard, and just skipping the heat-treat (some of the suggestions
I've gotten so far)? Is that going to stand up to coolant and time well
enough to have real confidence in my product? What do you folks think?
BTW, if anyone has pointers to exact dimensions for all (or any, really)
the various sizes of Aloris tool holders, I sure would appreciate hearing
about that, too. I've been seeking and not finding. I certainly want
to match their dimensions as they've become, pretty much, the defacto
standard, as far as I can tell.
Reply to
The other Thomas Gardner
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I would call forging an intentional work hardening process in many instances. It helps that in the process, useful shape is given.
Reply to
For me, 'forging' is a hot working process with no work hardening since the material recrystallizes. Maybe, I mistranslate the word, since I'm not a native speaker.
I would call deep drawing (=cold working) an intentional work hardening process in many instances. It helps that in the process, useful shape is given. ;-)
Michael Dahms
Reply to
Michael Dahms
Indeed, I was referring to cold-working. Sorry, should've been more specific.
Ditto. The local tongue confuses me, often times. :-)
OK, so does anyone have an opinion as to whether this would be a good method for obtaining wear resistant sliding surfaces? We're talking about a lathe toolpost here, so there isn't going to be a tremendous amount of sliding going on. Only when tools get changed. Nor would there be a great deal of pressure on the surfaces nor would the slide be at tremendous speed during the sliding operation. Not like a motor bearing which slides a lot, fast, and usually under pressure...
Other suggestions? In general, what's a ``really good'' material choice for machine tooling like this? Obviously, I'm worried about wear, but also corrosion (keeping in mind people do use a lot of water-based coolants). Toughness is a factor too. Would like it to be able to take the occasional mishap, and even a little abuse, without complaint.
I'd *REALLY* like to avoid heat-treatment if I can. That just seems like a lot of expense to me. More expense to me = higher price for customer = dead business = Tommy living under a bridge in his old age.
Sure, I assume I'll have to replace parts from time to time if I offer a forever-warranty, but I certainly want to keep it to a minimum. Is this whole cold-work hardening of stainless thing just a really bad idea?
Thanks, tg.
Reply to
The other Thomas Gardner
Why work hardening?
Michael Dahms
Reply to
Michael Dahms
At this point, it's all just guess after guess, but here are what I see as potential advantages (if this actually works):
1) Hardness without heat-treatment (wear resistance being the end goal, and hardness just a means to that end). Heat treatment just sounds too costly to me. Yeah, to build a machine to do the cold forming wouldn't be really cheap either, but the way I see it, the money up-front isn't worth worrying about as much as the operating costs. I'm thinking that the money, time and effort going into the machine would quickly pay for itself in significantly lower operating costs.
2) I like the idea of not having to worry about corrosion problems, even with water-based coolants in play. Stainless should be good for that. Most grades of stainless, if I understand correctly, also harden when cold-formed.
3) I suspect a good finish will be easier to achieve with cold forming than with cutting. I'd be doing both if I go with this: First cut to shape, a little oversize, then cold-form the rest of the way for hardness and finish. I'm thinking I could run the cutters a little longer if I don't have to worry about the finish they are producing. As long as they're cutting reasonably well, and I have the horsepower to drive them even a little on the dull side, they don't necessarily have to be bran-spankin' new sharp.
4) I'd get to build myself a really cool rolly-squeezy-mashy machine, and I'd get to watch it go! :-)
I'm trying to offer an exceptional deal. Breathtaking quality at cheapo Chinese import prices. I think my design will go a long way toward making my product cheap to build without sacrificing quality, but now I have to pick a material that will stand up to the ravages of time, coolant, wear and even a little abuse, but not be too expensive to process the material.
Am I living in dreamy-land? Go ahead, you can tell me if I am. I can take it. I'm used to it. :-)
Thanks, tg.
Reply to
The other Thomas Gardner
Work hardening always leads to a much lower hardness than hardening by heat treatment or coating.
A work hardened surface is less noble than an unworked one.
In general: Let someone do the work, when you need real quality. It's always cheaper than do-it-yourself.
Michael Dahms
Reply to
Michael Dahms
Yes, I actually did kinda come to this conclusion myself. I wasn't certain, but I was getting that impression. Thank you for making it clear.
However, all I'm after is for it to be hard enough to wear well. This is for the sliding surfaces on a lathe toolpost. This won't be sliding a lot, only on tool changes. I guess I did mis-speak last time: There will be sliding under pressure: When the wedge is tightened, that will definitely be sliding under pressure, but momentary. Anyway, all that to get to the question: How hard does it really need to be? Under those conditions, would the work hardening be hard enough to resist wear well? Would I be better off with either 4340 cond. med. or 4140 prehard, without heat treat after machining (as were a few suggestions I did get) for wear resistance? Something else entirely, maybe? What kind of corrosion would I expect to see (keeping in mind the coolant)? Devastating amounts or just a very mild surface rust? The latter, I think my tool post can still function with.
I'm afraid you've lost me. I don't know what being noble means in this context. What are the implications of that statement?
I don't know how else to say this, but I'm just not interested in that. I'm trying to completely change my life, here. I'm not the slightest bit interested in getting someone else to do for me that which I long to learn to do, and learn to do extremely well. I need to learn, if I want to do this well. I know I've got a long way to go, but I've got to start somewhere, and I'm willing to put everything at risk to get there, but only if I convince myself that I will be successful in the venture. This is about me trying to completely change my life, not gold fever, and certainly not just trying to scratch an itch.
Thanks, tg.
Reply to
The other Thomas Gardner
I got this in a private email (won't give the person's name/mail, if that was desired by the sender, sender would've posted to the group):
I'm thinking something like a bead-blaster loaded with stainless beads of some sort. Rail-gun, perhaps? :-) Could such a thing actually work? Anyone else ever hear of this process?
Reply to
The other Thomas Gardner
"The other Thomas Gardner"
Sounds to me like what you need is that rare, and hard to find Unobtainum. But cast iron should work in any case.
Reply to
Diamond Jim
So far you have written a lot of information, but I guess I'm just a little bit confused with what you exactly need. Are you just looking for surface hardening and corrosion resistance, or are you looking to harden the whole piece at once? If the answer is just the surface, some sort of peening process would then in theory work. You can think of it as a bunch of ball bearings repeatedly hitting the surface which causes plastic deformation (the depth of deformation depends on the force they are hitting the surface). This plastic deformation leaves behind residual compressive stresses which can improve the fatigue life of the component.
You have to remember though that the case hardening done with any sort of boronizing (which is done with tool steels, but I don't know about the lathe pieces) you will always get much more wear resistant cases simply because they are much harder.
Corrosion resistance is an issue which I can't necessarily tell you would be improved. With shot peening you may get rid of surface cracks, but the surface isn't going to be perfect, plus there will be more atomic disorder. Cold work processes such as burnishing (surface rolling) can improve corrosion resistance, but this effect is due to improved surface finish.
In all I think you need to look at the effects of any sort of peening process on the specific materials you are looking at. Now I'm still not sure of what part of what you need hardened, but these processes have been around a long time and they may not use them in industry for a reason. Once again, I'm no expert on that, but it is just something to keep in mind.
Reply to
Seth Imhoff
Sorry. Indeed been writing a lot, but mostly, I guess I've only been spewing confusion. I'll try to be more clear.
Essentially, I'm trying to select a material. Yes, I'm very much interested in both corrosion resistance and wear resistance. I *THINK* the sliding surfaces' hardness will help with the wear resistance, that's why I'm worried about hardening. As such, I suspect hardened through and through would probably not be necessary, but I don't know for sure, that's why I'm out in public making a fool of myself. I'd rather display my ignorance for all, and learn something in the process than remain ignorant forever.
I'm also deeply concerned about cost. The whole heat-treat thing just sounds way too expensive to me. Although if I decided I wasn't going to be able to avoid it, I suspect I'd prefer a material that can be air quenched (if I can get what I need out of it, of course).
This made me think of stainless: Corrosion resistant, and from what I hear, hardenable by cold forming. On the surface, it sounds like a match made in heaven, but I really don't know enough about this. That's why I'm hoping one of you kind folks out there might have mercy on me and help me obtain a clue.
It all comes down to: I want to provide an exceptional value. An extremely good tool for an extremely good price. I think my design simplification will make this tool (quick change tool post for a lathe) much cheaper to make, so, I shouldn't have to skimp on material. I do have to be careful of the special processing costs, which is why I'm so worried about the whole heat-treat thing.
Sounds promising. What kind of depths could one hope for? I suppose that's the big trade off there though: Deeper hardening means I have to bounce the balls harder, which in turn would mean a surface finish that just wouldn't be appropriate for sliding. Eh?
Yeah, sounds spendy, but I have to keep my mind open to it. Thanks for pointing out that this is what's normally done on tooling. That could be the most useful information I've gotten so far. I don't even know what the ``normal'' processes are. Man, I'm really just shooting in the dark, ain't I?
Well, that's where this whole stainless thing was going. The shot peening thing was just a means of work-hardening the stainless to improve it's wear resistance, in my wee-tiny little mind.
That's actually where this all started: I was initially thinking of a rolling process to both harden and give a fine finish to the sliding surfaces. It was just an idea...
To be honest, neither am I. I suspect a case harden would be sufficient. Would hardening it through and through provide any longevity, or abuse or mishap resistance to a tool post? Man, I wish I knew more about this sort of thing. I wish I even knew where to look for it. There's so much stuff out there, and stabbing in the dark is quite time consuming. :-)
Yeah, no kiddin. Lots of stuff on that list. And it only seems to keep growing. :-)
Thanks for the insight and help, tg.
Reply to
The other Thomas Gardner
"The other Thomas Gardner"
Most stainless steel galls easily and doesn't slide well with out a lubricant. Most good lubricants for use with SS are blended, not plain oil/grease.
As most machine tools use a lot of coolant/lubricant, corrosion resistance is not a major concern. When you clean your machine up after use, you insure that the metal is protected from corrosion. Cast iron (actually plain iron as most of it really isn't cast anymore) is fairly corrosive resistant anyway, and with a minimum of lubricant wears and slides well.
I just don't see the need for a stainless steel tool holder. You tool holder may be a world beater, but there is no need for it to be made from stainless. Now an armature that only uses a lathe once a month or so and forgets about it the rest of the time might benefit from stainless, but for a machine that is used daily its a waste, why not use something that has other properties that are more useful.
Reply to
Diamond Jim
less noble = lower corrosion potential = easier corrosion
Michael Dahms
Reply to
Michael Dahms
Yes. It works.
Michael Dahms
Reply to
Michael Dahms
I should have made this clear before, but I know I didn't, so I shall now: I am in no way at all wed to the idea of using stainless. I am only wed to the idea of using whatever it is I need to use to get the best performance I can get out of the cridder at a good price. If it turns out to be too expensive a process to offer the tool at a really good price, I will either go with a second-best choice, if it still proves itself worthy, or I will simply abandon the idea and go on to the next. I do not want to produce a high-cost luxury item. Nor do I want to produce junque. Great quality at a price the home shop or very small business owner can easily afford is the goal. Stainless, work hardened on the sliding surfaces for wear resistance was just one idea I thought I'd bounce off the group. If I decide it's a bad idea, I will just abandon it.
Don't worry. I'm not a bulldog. I don't hang on to things forever.
Diam> Most stainless steel galls easily and doesn't slide well with out a
Well, the sliding would be minimal. Only on tool changes, relatively low speeds, etc. I was under the impression that galling was primarily a concern with higher speeds and lots of motion (like in a bearing on a motor). Was that just a complete misconception on my part? There will be a momentary burst of somewhat higher speed, very high pressure sliding, right when the user drives the wedge in, so I was concerned that galling might be a concern, but I just didn't know enough to know if that was a concern or not. Your opinion is that it really is a concern, then?
You know, I wasn't that worried about it until I started reading horror stories about people destroying their equipment with the use of water based coolants. Were these articles written by folks who didn't know what they were doing and just ruined their equipment by doing something stupid (in your opinion, of course)?
I think I can live with replacing the occasional part because the user did something stupid. I expect that to happen anyway. I just didn't want to get stuck replacing a bunch of stuff 'cause I picked the wrong steel and it rusts out like crazy with the normal application of coolant.
You know, I was wondering about that. However, isn't cast iron brittle? Will it stand up to shock (if dropped, does it crack) Will it stand up to having that wedge driven in over and over again, or will that stress it out and make the little dovetail pop off in short order? I know they don't use the stuff for bolts, and I thought that was the reason why: Just too brittle and not strong enough, and the heads would just pop off when tightened.
This is exactly the reason I came here. I just don't know enough to make an informed decision. But I know you folks can sure clue me in.
Absolutely! That's my real end goal: Material selection. If stainless just isn't appropriate for the job, I'll drop it in a heartbeat without any reservation whatsoever. Using stainless for it's corrosion resistance and work hardening it on purpose for wear resistance was just an idea I thought I'd bounce off the group, mainly 'cause I couldn't find any information on the process. I knew much of the stainless family did have that property. I found lots of references to that, but I couldn't find any references to people using it to their advantage. Maybe there is a reason for that, eh? :-)
So, if you were going to try to make a wedge style quick change toolpost, and you were trying to make it last as close to forever as you can get, what would be your first choice for material? You do bring up an interesting point: The properties I would want for continuous, heavy duty use are not necessarily a good thing for the occasional home-shop user. It never dawned on me until now that the occasional use model actually has a completely different set of design parameters than the continuous use model. I always assumed it just came down to price, so I was trying to aim for industrial quality at a price the home user could afford. You've opened my eyes to the subtlety there. Thank you.
In that light, I'm absolutely not afraid of offering different materials for the different usage models. That is something with which I can very easily live. I can just inform the user what the real difference is, and that it's not about price, and they can make up their own mind.
So, if you'd like to throw in suggestions, and give me the attributes you like about your choices, man, I would really be in your debt. Right now, I'm just floundering, and I'm painfully aware of that. As I've said, I'd like to avoid heat treatment, if at all possible. I suspect that will just be too expensive for the price range I'm shooting for. However, I'm not wed to that either. If I find it's not as expensive as I think it is, and find it's really the best way to go, I'd jump on that bandwagon with both feet.
Got any miracles for me? :-)
Thanks, tg.
Reply to
The other Thomas Gardner
In article , snipped-for-privacy@ElectEngrngCompSci.CaseWesResUniv.EDU (The other Thomas Gardner) wrote:
You're making this way too hard (pun intended)
Heat treating is not that expensive.
If you want it hard, and you want it cheap, and you want to quit fooling around and git 'er done, here's my suggestions in no order:
1] 416 stainless. Used a lot so it's cheap. Heat treatable. 2] 4130 alloy steel. Used a lot so it's cheap. Heat treatable. Not very corrosion resistent, but fine in a shop environment. 3] H-11 tool steel. Used a lot so it's cheap. Heat treatable. Not very corrosion resistent, but fine in a shop environment.
I also use PH13-8Mo a lot, and it's a very versatile alloy.
Pick a couple and price out the material/heat treat. Then you'll know.
Reply to
Harry Andreas
Wow, Harry! Thank you so much. I'll be looking into your suggestions.
Harry Andreas wrote:
Well, it *SEEMS* expensive. :-)
I don't have ballpark figures to go by right now. If you happen to know some, I sure would appreciate hearing them. For instance a ``C'' size tool post (the size I happen to be using on my machine), is in the neighborhood of about, say, a cube of steel roughly 3.5" on each side.
Do you have a rough idea what I might expect to pay to harden and get the most out of the various selections you have down there? We'd probably be talking about reasonably large quantities (possibly a few hundred in a squirt, I'm guessing). Hafta getsa good grinder, but that's OK.
Figured out how to find rough idea prices on steel in large quantities, so I'm good there.
This was one I had been looking into. Another was 4340. I was starting to get the impression that 4340 was tougher, got harder in heat-treat and a bit more corrosion resistant. You have an opinion? Wasn't that much more expensive to worry about, if I recall correctly. More costly to machine, but that would be my trade-off.
Well, material I think I have figured out how to rough-guess the price of. No idea how to do that for heat treating. If you have any pointers on where to go looking, I sure would appreciate it.
I can't thank you enough for your help. If I do end up making my dream come true, and you did indeed just lead me to the answer, you just let me know what size your lathe is and I'll get you fixed up. Don't hold your breath 'cause it may never happen, and if it does it'll take time to ramp up, but if/when it happens, I'll stick to my word.
Reply to
The other Thomas Gardner
Ok! Your site is pretty, but this is cooler! :
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Ok! Your site is pretty, but this is cooler! :
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