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.
Thanks, tg.