What does heat treatment cost?

Subject pretty much says it all: What can one expect to pay for various forms of heat treatment (for hardening, not annealing)? I've been under the assumption that any kind of heat-treat is pretty spendy, so I've been trying to pick materials that can get by without, but some folks are telling me it ain't so bad. I can find no pointers on price, though. Not so bad to one guy could be a back breaker to another...
I know different materials are going to require different procedures, so I would expect the costs to vary. However, does anyone have have any rules of thumb to get me in the ballpark of what I might expect for at least a few of the various procedures? Knowing the price differences in the treatment types would also help me in material selection.
For a general idea, think a cube of steel about 3.5" on a side. That should be about the right ballpark. Probably doing these in respectable quantity, like maybe a few hundred in a squirt. Not vast quantity, but respectable.
Thanks, tg.

Heat treating doesn't have to be expensive unless you want to rent a high priced brain. you can do small tempering with a gas burner or charcoal grill. Larger items are done with open forge fires or furnaces, which runs up the price. Tempering theory is simple: Quench from a red heat to harden, using oil or water as a coolant. Draw [read soften] the temper by low, uniform heat between 250 and 600 Degrees F. The surface of the polished steel will indicate the proper draw point by the color of the oxide formed: straw yellow for razors, gravers & other very hard [but brittle] tools. Ruby red for cutlery and cold chisels. dark red to purple for high impact tools like axes and pick points. Deep purple is spring temper. Black is annealed and soft again. That is the bare bones basics of tempering steel. Different alloys have their own characteristics, so there's an infinite array of possiilities. Bugs

Thanks.
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I think my heat treating costs are cheaper than the shipping to the heat treater so I drive the 2 miles. I'll do small, one-offs in the shop. Like everything else, supply and demand...are there a few firms in competition around the neighborhood? Don't do it at home, it's another job that will steal part of your life and cost WAY more than you think. Are these parts for your "time machine" design? Get to work on the motor!!!! ...or you will be labeled "The Prince of Procrastination" (I'm the KING)

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Tom Is your brush website email down? I sent you a message the other day.........no reply. Steve

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try: tom-at-ohiobrush.com (use @ instead of -at-)

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I figgered that much. I'm definitely thinking ``close to suppliers'' when I go looking for my location. So, if you've got, say, 1000 lbs or so of stuff to go off to the treater. Say you're after a case harden. Medium depth. What do you expect to be reasonable? Ball park?
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Yeah, me too. For my own stuff. I'd prefer to treat customers with a little more respect than that, though. :-)
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Ain't found 'em yet. You know how that goes: You call an industrial service company on something you're not sure about and you get run around if you're lucky. Ignored, primarily, and if you can talk them into doing business with you later they generally charge you 10X...
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No kiddin. That's why I'm tryin' to put feelers out.
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Yup. Although most folks call it a tool post, that's pretty much what I'm hoping it might turn into: A time machine.
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After giving up on my last time machine and going back to the motor work again, I later turned back to the time-machine theory (but with different specifics): Make something to sell that won't consume every waking moment so you have at least a little time for motor research. This QCTP just might do that for me. Still in the research stages. Ain't even hammered down the material yet. The old man used to tell me that was the most difficult part of any project. Although I didn't doubt him, well, now I'm really tasting that for myself.
The motor hit a bit of a snag (actually several, but I worked through all but one). When I finally figured out how to do more of the calculations with the latest design with all the other snags worked out, I found that it is not too useful in the smaller sizes. My target market was going to be to start with toys (RC cars and whatnot). You know, a niche group. I'm having to go back and redesign for the larger sizes now (no less than, say, 1 or maybe even 3 HP minimum). I'm thinkin' the new niche market might be home-shop folks who want to convert their machinery from 3 phase to single phase on the cheapy-cheap. Any ideas where I might find such folks? :-)
Actually, with such a restriction, I'm honestly starting to doubt if this is even worth pursuing any more. Just like that. 15 years down the dumper...
Anyway, I've had to go so far back on the drawing board, well, I think I'm looking at a blank sheet again. I'm still going to build the one for which I have the plans and steel. I need to make sure that my calcs be right. Could be I'm off by a few orders of magnitude (and I'm off that far IN TH RIGHT DIRECTION). It's been known to happen before.
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Yeah, well, more scatter-brain than anything else. Just have too many projects underway, and always dreaming up new ones.

Hey TOTom,
Give a yellow pages call, or try the closest Thyssen Marathon. They will give you prices, but ask LOTS of questions. If you waive damage claims, are willing to wait, and your stuff is small enough to go in with a big companies load, and it's not some critical material, prices may well be below $10
Take care.
Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXXXXX On 13 Oct 2005 12:41:37 GMT, snipped-for-privacy@ElectEngrngCompSci.CaseWesResUniv.EDU (The other Thomas Gardner) wrote:
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Thanks a bunch. This at least gives me an idea. I appreciate the insight.
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I've dealt with at least a couple flavors of heat treating outfits: We used a small tool and die orientated place that would do all of our special cutters, punch dies, etc. They did all of their work in small ovens, fully instrumented, dealt with tool alloys all the time. Just specify the alloy and the Rockwell and you got it back two days later. It's been a few years but IIRC they had a minimum charge of about $35 to run one part or small group of parts. More weight meant longer time in the oven and a few $$ more.
The other shops were high volume production places. We also did one job that had 16 4130 frames mounted in a rack that went into a 8' diameter by 16' deep pit furnace. 3 pits in a row, (high temp, quench, temper) with an overhead crane. $500 for the lot.
These same shops had all sorts of other equipment: conveyor furnaces, vacumn furnaces, batch furnaces, etc. Pricing is dependent on the handling required (manual placement vs conveyor), special treatment (nitrogen atmosphere for nitriding), and length of time in the furnace (thick part need a longer soak time)
I'm sure that you can get some competitive bids once you get to 100 at a time. I'd toss out a SWAG number but you really didn't give enough detail on the part.
Keep in mind that if your "cube" is anyere near solid (eg a block with a few holes drilled in it), heat treating gets real fussy. It takes a longer time to get the whole part up to temp, quenching evenly is difficult. And then there is the warpage and shrinkage problems. If you just call up a volume place and dont have ready answers about what tolerances you can live with, they will give you the run around.
The other Thomas Gardner wrote:
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This is excellent info. Thanks.
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That'll probably be close to my situation, I believe. Having a hard time picturing the volume, though. You recall approximate thicknesses on your parts? What kind of tonnage would you guess on that?
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That's exactly what I'm hoping for.
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Well, a 3.5" per side cube is pretty much it. Of course it's got dovetails cut on 2 faces (this is a QC lathe toolpost). There are some other bits taken out hither and yon, but mostly, it's really pretty close to a solid cube. If you'd care to SWAG that, you *SURE* wouldn't hear complaints from me. :-)
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Yeah, well, I assume I'll have to do some grinding when it comes back. Another reason why I was (and really, still am) hoping to pick a material that would be wear resistant enough for the job even without heat-treatment.
I've been reading like crazy trying to educate myself, and somehow or another, I seem to have gotten the impression that warpage and shrinkage problems are worse, the faster the quench process required for the material. So, for instance, a water quench will warp parts far worse than an oil quench. Is that true? If so, what about something that can be air hardened? Wouldn't that be slower still, and therefore deform parts even less? Of course, I also seem to recall that big honking thick parts like the ones I'm talking about, would have to be oil quenched, even with air hardening materials chosen (part just won't cool down fast enough in air if it's too thick). Is that something I just imagined?
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Exactly! Trying to find my clue now. I'd rather find it in a newsgroup than with a dealer where it could cost me oh, so dearly, in oh, so many ways.
Thank you so much for your help. I do appreciate it.

On Fri, 14 Oct 2005 02:05:31 +0000, The other Thomas Gardner wrote:
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If the heat treating is just for wear resistance have you thought about case hardening? I don't know much about the commercial process, but Kasenit doesn't require quenching.

Indeed, I was leaning toward a case harden anyway.
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What grade(s) did you have in mind with that statement? The less exotic I can get on the processing the better, in my book. The less deformation, the less post treat processing, all that, the better.
Thanks for the input.
L8r, tg.

On Fri, 14 Oct 2005 15:50:41 +0000, The other Thomas Gardner wrote:
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It seems that I may have been wrong about this after all. I could have sworn that I'd read something online about using Kasenit and not having to quench. I even remember being impressed by that because it seemed like that would lessen the chance of the parts warping. Now, as I attempt to look that reference up, I can't seem to find it, and most discussions of using Kasenit talk about quenching as part of the process. Disappointing.
So I apologize if I am wrong on that. I should've checked my facts before posting.

Egads. How embarrassing: I'm so ignorant, I thought you were just making the word Kasenit up (i.e. ``casing it doesn't require quench...''). Never dawned on me that was an actual product name. Obviously, that's something I hadn't run across yet.
Tommy ``big doofus'' Gardner.
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about
exotic
deformation,
Kasenit turns the surface of plain steel or certain low-alloy steels designed for case-hardening into very high-carbon steel -- plain high-carbon, if you start with plain carbon steel. It works by diffusing carbon into the steel, from the outside in. Thin cases may be only a couple of thousanths of an inch thick. It's possible to produce thicker cases using special methods, and some industrial process can produce a 1/4-inch-thick case or even more.
Hardening any steel by martensite conversion (which is the hardening process we're talking about here) requires a rapid quench through a certain critical range of temperatures. Different alloys require different quench rates. Plain high-carbon steel requires the fastest rate of all, on the order of a few seconds, which is why it typically is quenched in plain water or brine. Air-hardening steel, as the name implies, is at the other end of the scale: the quench rate can approach an hour. But that's not case-hardening with Kasenit. That's through-hardening of a special alloy made for slow quench rates.
If you want maximum hardness from a thin case in steel, such as one you get with Kasenit, you have to use carbon-steel quenching rates and methods. That usually means a water quench. There are some rare exceptions, such as extremely thin blades or very large, thick masses of steel or iron that you surface-heat with a flame or other means (thus, flame-hardened lathe beds), which self-quench when you heat them quickly and then take the flame away. But think in terms of water quench if you want a really hard case, on the order of Rc 62 or higher, for any normal application.
What you probably read is that you don't have to *temper* a case the way you do with through-hardened steel. That's generally true, if the case is thin and if you aren't going to beat it with a hammer. But you then have a brittle, if extremely hard case -- perhaps Rc 70. It makes a great wear surface for bearings of many kinds but you wouldn't want to try it on a very thin section that had to flex, or it would crack.
Ed Huntress

Thanks a bunch, Ed. Very, very clear and useful information. I sure do appreciate it. With one post, you've cleared up more things in my head than I suspect you realize. Of course, there's still a lot of clutter up there, but every little bit helps. :-)
Man, there's a tremendous wealth of knowledge in this group.
Thanks, tg.
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'Glad to help, Thomas. You may be interested in one other point about case-hardening versus through-hardening: Quenching low-carbon steel that has a thin high-carbon case causes less warpage than quenching high-carbon steel that hardens all the way through -- all else being equal. You can still warp the heck out of a case-hardened part but you have to work harder at it. <g>
Warping that results from quenching steel can be a complex thing. Part of it is due to thermal expansion and contraction of the steel, and uneven cooling that leads to uneven stresses and strains; and part of it is due to the fact that the hard phase of steel (martensite) is less dense than the soft phase (ferrite), which leads to differential expansion upon quench-hardening, unless the quenching is perfectly uniform.
So a thin case of martensite imparts less stress than thick layers of martensite. More important for many applications, the soft steel underneath winds up with fewer internal stresses because it doesn't convert to martensite upon quenching. The case-hardened piece may be tougher and is sure to be less brittle overall. That's an important property that makes case-hardening a useful technique. It's used in the highest-quality, high-speed gears, for example, while through-hardening is used in somewhat cheaper gears. In between is flame- or induction-hardening, a surface-hardening method that's used in many large industrial gears.
Ed Huntress

Sorry, been out in the shop. Ignoring the 'puter...
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Any help, you have. And it just keeps comin, too!
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Thanks again. Some great stuff in here. Already saved it off.
L8r, tg.

On Fri, 14 Oct 2005 23:57:27 +0000, The other Thomas Gardner wrote:
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I'm sure that's only because you haven't gotten a round tuit yet.