Any wire EDM and Laser or electron beam welding experts on line? - Page 2
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  1. #21
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    Quote Originally Posted by moonlight machine View Post
    Target date for completing this project is June 1st.
    I would say that strongly depends on your customer’s failure tolerance.

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    Man you have a tough job making that deadline
    Hope the guy who wants it understands what is being ask.

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    Quote Originally Posted by 72bwhite View Post
    Man you have a tough job making that deadline
    Hope the guy who wants it understands what is being ask.
    You don't know the half of it. The gear is a bump- in the road.

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    it seems that as welded (electron/laser) 300m still fails in a ductile manner in the tensile test while loosing around 50% of fatique strenght. 4340 looses 15%. that makes me believe the results will be very dependent on the exact alloy composition.

    perhaps i didnt catch it, but you are not considering heat treating the parts?

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  6. #25
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    Quote Originally Posted by dian View Post
    it seems that as welded (electron/laser) 300m still fails in a ductile manner while loosing around 50% of fatique strenght. 4340 looses 15%. that makes me believe the results will be very dependent on the exact alloy composition.

    perhaps i didnt catch it, but you are not considering heat treating the parts?
    I really don't want to, one of them has a roller bearing race on it.

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    What you need is at least 2 clones of you
    Been around a little racing and car building
    Forest Lucas used to race at the local fairgrounds
    With pintos.
    Better owner and sponsor then driver he is

  8. #27
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    Quote Originally Posted by 72bwhite View Post
    What you need is at least 2 clones of you
    Been around a little racing and car building
    Forest Lucas used to race at the local fairgrounds
    With pintos.
    Better owner and sponsor then driver he is
    Yeah, for sure. when I hire someone I just expect them to know what I know. I am always disappointed, but at least if they just had some common sense! Common sense is not so common anymore. Owners...Did you see that Roger Penske drove a LMP2 Porsche last week? Serious car 200 mph, 84 years old! And from what I hear he was not slow.

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  10. #28
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    Hi again moonlight machine:
    You asked about a permissible gap between surfaces that will still permit an electron beam weld.

    Again, I am not experienced with this technology specifically, but if you are making a butt weld through thick material, logically the fit should be as tight as you can possibly make it.
    I say this because if there is a space, the molten metal will have to cross the gap to coalesce into one melt pool.

    This has a couple of bad consequences:
    1) As the metal cools and the puddle consolidates it will shrink and need to draw from the two joint surfaces to fill the void.
    This will stress the part and pull it out of round assuming the weld survives.
    Some metals have a tendency to hot crack as the metal transitions from liquid to solid...a gap makes this infinitely worse and hardenable steels typically show this undesirable property to some extent.

    2) You can't add filler to the center of the joint, so all the metal required to fill the joint must come from the parent metal on both sides.
    As you start welding, the weld occurs only at one place around the circumference and the parts will try to pull themselves in toward the hot zone, so keeping the two elements reasonably concentric to one another will be extraordinarily difficult to do.

    I don't know what AGMA class transmission gears typically are...I'm guessing 10 or thereabouts.
    The concentricity requirements and the circularity requirements of the pitch circle for typical automotive transmission sized gears I would expect to be in the sub thousanths range for that AGMA class, but I'm guessing here too.
    Maybe someone with automotive gear manufacturing experience can chime in.

    If my babble is true, that's an extraordinarily ambitious target for a welded assembly, and I don't believe it matters much what process is used, whether laser or EB welding.
    I'm sure it can be done, but I don't believe it can be done with a big weld gap to fill.

    So, if I'm at all correct, you may need to sleeve the bore you cut in the gear, and then make the hub to suit, so you have as small a gap as possible...a shrink fit or a taper fit as was advocated by newtonsapple would sure be nice, but it would mean you have two joints to make, not one.
    Nice thing is, with a wire EDM you can make both of those joints splined and micron accurate with ease, regardless whether you have them tapered half a degree or not.
    You can cut the bore in the gear, weld in a plug and then wire the plug to make the new bore, effectively mitigating the shrinkage induced distortion from the first weld (we hope!)

    You can wire the hub OD first, using the gear itself as the holding fixture to rough and skim it, then use the finished hub as a plug gauge to size the bore in the gear after the sleeve is welded into it.
    You could also make the sleeve skinny enough to hit both sides of the joints with one weld...maybe.
    You'd have to ask your EB welder if it's feasible.
    In that case the sleeve acts like a glorified piece of filler wire, and is completely consolidated in the weld.

    This is all a tremendous amount of fucking around...you can't just find a couple of vendors to take this on without them accepting what a project it's going to be, so you may have a goodish challenge finding someone, and if the target date is 2 weeks from now, I forsee some difficulty on that front alone.

    So no, I don't think you can tolerate a gap...even a few microns seems problematic, and if you MUST preserve both gear and hub, this is the only way forward I can think of.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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  12. #29
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    This is a question, not a suggestion. Using WEDM, leave three points connected and do this with as many passes as needed:




    Use 300m, maraging or whatever ground pins to make the connection. It might be bolts and nuts with threads peened or rivets cold riveted.

    Of course, it will never be as good as original, but might work with reduced horsepower or would it?

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    Hi David M:
    Your idea has a lot of merit; I think it's a very clever way to maintain the concentricity and fill a good part of the gap at the same time with simple pins.
    My biggest concern is the stress you'll put on the gear as soon as it sees substantial torque.
    Each of the pins will act as a little cam and the torque will try to force the pins into the slots, splitting the gear and collapsing the hub.

    Now I know roller clutches look something vaguely like this on the inside...what kinds of torque can a similar sized clutch tolerate and how is it built differently from the gear to accommodate that stress?

    That analysis will go a long way to informing you whether the gear has a chance to survive.

    It's a great idea though, and solves a lot of the problems the OP has with this project.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    Late to this thread, but I wouldn't suggest welding in this application. Electron Beam Welding (EBW) although is a good idea here, is going to be expensive and there are not many shops around that do EBM job shop type work. Even if you are able to get the welding done, there is still a chance of issues with discontinuities and irregularities in the weld area that would make the material susceptible to impulse forces and fatigue fracturing. There are other issues with concentricity, run out, and balance after as there is always some deviation in joining two parts when welding as the stress introduced during cooling is enough to pull the parts out of radial alignment, or concentric alignment. For a gear box that will see the rpms that this will see, considering the contact surface of the tires and track, and the cost of repairs if a component fails (gear case, engine case, etc) I would highly advise against welding. Also, one thing to consider there maybe class rules or rules from the governing body that prevent the use of such parts on the track. Even the idea of cutting splines to mate the two parts together is a toss up. At the level your driveline is operating at, and considering the tolerances from the initial design I would suggest getting new gears cut. I have seen some pretty crazy damage to engines and gear boxes from modifications like this, (SCCA, NHRA, NTT Indy,etc) they all frown upon this. Dumping your gear box oil on the track then being responsible for the damage to the other cars is not something taken lightly, not at the speeds you are talking about.

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  18. #32
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    I have done something similar to the round pin idea by using 0.093" diameter ground HSS pins riding on the the involutes of a male spline and clamped on by a Ringfeder type coupling. This was much lower stakes, just mating an automotive transmission to my dynamometer.

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    Quote Originally Posted by SShep71 View Post
    Late to this thread, but I wouldn't suggest welding in this application. Electron Beam Welding (EBW) although is a good idea here, is going to be expensive and there are not many shops around that do EBM job shop type work. Even if you are able to get the welding done, there is still a chance of issues with discontinuities and irregularities in the weld area that would make the material susceptible to impulse forces and fatigue fracturing. There are other issues with concentricity, run out, and balance after as there is always some deviation in joining two parts when welding as the stress introduced during cooling is enough to pull the parts out of radial alignment, or concentric alignment. For a gear box that will see the rpms that this will see, considering the contact surface of the tires and track, and the cost of repairs if a component fails (gear case, engine case, etc) I would highly advise against welding. Also, one thing to consider there maybe class rules or rules from the governing body that prevent the use of such parts on the track. Even the idea of cutting splines to mate the two parts together is a toss up. At the level your driveline is operating at, and considering the tolerances from the initial design I would suggest getting new gears cut. I have seen some pretty crazy damage to engines and gear boxes from modifications like this, (SCCA, NHRA, NTT Indy,etc) they all frown upon this. Dumping your gear box oil on the track then being responsible for the damage to the other cars is not something taken lightly, not at the speeds you are talking about.
    I don't want to do it at all. I am looking all over for the correct ratio, overdrive drop gears are a bit thin on the ground for a '99 Reynard Indy Car.

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    I am going to just send a PM as I think there is some restrictive information a.k.a. "giggle" intent here. The hot-rod cool factor is only worth it to the first guy to come up with the idea.


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