seized SS shaft.

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Any one know any tricks to un-seize stainless. I've encountered this many time over the years and have never had success. The norm is having to destroy the parts. The most recent is a 3/4" SS shaft running thru a 6" long carbon steel bushing-guide. The original fit was a nice smooth slip, no lateral play. The bushing was then welded to a fixture with the shaft inserted..Guss what...now it can't be press apart..Any trick  any one???Miller TrailBlazer 251Miller HF-250-1Miller MaxStar 150 STLHyperTherm PowerMax 380 plasmaLincoln PowerMig 180Millermatic 252Miller Diversion 180
Reply:Try freezing it.Millermatic 251Spectrum 300 PlasmaEverlast PowerTig 250EXEverlast PowerCool W300Harris / Victor OACraftsman 13 Speed Drill PressProTools Air/Hydraulic Bender48" BrakeCompressor, Notchers, Grinders, etc.
Reply:My guess, the bushing is distorted.  Your customer is up the creek.  The only solution I know of is a pre-emptive one.  Weld the bushing before final machining is done.  As far as getting them apart without destroying them, I think you don't have an prayer.  I assume you've tried penetrating oils and such to try and free things up?If you can flash heat the bushing without heating the shaft, they might slide apart. Or the heat may further distort the parts by relieving residual stresses; and make the problem worse...Wish I could be more helpful... Originally Posted by waginAny one know any tricks to un-seize stainless. I've encountered this many time over the years and have never had success. The norm is having to destroy the parts. The most recent is a 3/4" SS shaft running thru a 6" long carbon steel bushing-guide. The original fit was a nice smooth slip, no lateral play. The bushing was then welded to a fixture with the shaft inserted..Guss what...now it can't be press apart..Any trick  any one???
Reply:what are the costs of the parts? is it worth how many hours of labor to mabe get usable parts or is it cheaper in the long run to just buy new parts and put it together the correct way..
Reply:When you said "seized stainless shaft", I thought you meant "seized".  As in stainless on stainless seizing.  Which is actually a form of welding, btw, because it is the stainless steel physically welding itself to the other piece of stainless steel.  And the reason why AntiSeize was invented and should be used.  Liberally.  As I learned looong ago with some stainless marine fasteners that seized.  Removal entailed the longest cheater bar we could find and wield and the ultimate destruction of the fasteners (at least we got them removed).  Before any more work was done on that job, a quick trip to the local industrial supplier was made for some AntiSeize.Anyway, what you have sounds more like the shaft is jammed or locked in place because someone unwittingly ended up making a shrink fit of the bushing and the shaft.  As such, the two pieces have now achieved a sort of Zen state of Oneness.  Basically you're SOL on that one dude.    Parts will have to be destroyed to remove them.  Some sort of cutting/grinding/flame (plasma counts as a Dang hot flame in this case) to remove parts.Better procedure next time is to line up the bushing with the shaft in place, and REMOVE the shaft before welding the bushing.  Then possibly line-bore or hone the bushing after welding (and cooling) so that the hole is correctly sized and positioned.Welds -always- shrink.  When the weld on the bushing shrank, it also shrank the bushing ID.  Which is now smaller (to some extent) than the shaft OD (or would be if the ID weren't restrained by the OD    )  which now means a shrink fit has been formed between the bushing and the shaft.Unless you can get creative and apply intense cold just to the interior of the shaft (drill the shaft out and apply liquid nitrogen) to make the shaft OD smaller before the cold also gets into the bushing and make -it- colder and shrinks it more, or unless you can apply localized intense heat fast to the weld(s) and get them to re-expand slightly before the heat gets into the shaft and makes it expand as well, and remove the shaft while the temporary thermally-induced expansion/contraction differential is in effect, you'll have to destroy one or both parts to get them apart.If the original fit of the shaft into the bushing was a nice smooth slip fit without slop, then there was maybe 1-5 thou clearance between the parts.  It doesn't take much weld distortion or shrinkage at all to change the formerly nice slip fit into a shrink fit between the bushing and the shaft.  The best laid schemes ... Gang oft agley ...
Reply:Wagin,This is a tough one.  As others have mentioned, I suspect the seizing was caused by welding the part with the stainless shaft in place.  Probably would have been best to weld the part, machine, and then insert the shaft.Not real crazy about SS to mild steel regardless whether anti-seize is used or not.  This is why silicon bronze is often used for bearing material.You may try a little liquid nitrogen on the SS shaft to freeze it (shrink).  If that doesn't work, I suspect you're fulked.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:You said this has happened to you before,,,,,   you haven't learned yet???I weld plenty of bushings/pivots/rotating items in place, big thing is if I don't need real precision I specify to the machine shop .010 to .020 clearances.   Both with steel to steel, and steel to bronze/brass.  This is usually enough that the shaft will still slide in without any more honing or machining.   For real precision, if necessary, the only way to go is do the rough machining, weld it, WITHOUT the shaft in place, then re-machine before final assembly.I just finished a walking-beam set-up, mounted on 4" shaft.   4' long beams, welded the pivot into 4x6x3/8" tube, bushings were steel with bronze inside, correct clearances, slid on fairly easy, no perceptible slop.  Didn't re-machine or hone either.In this case, the fact you are using a SS shaft is immaterial.In this case, just to get it out, I would find the biggest rosebud you have, start heating the outside sleeve, have somebody tapping on the end of the shaft the whole time.   TAP, don't bang, you don't want to mushroom the end.  Doesn't take that much heat, and at least if you can see and observe, you will note where the heat does the most good.   As mentioned earlier, if you also get the shaft over-hot, you are pissing against the wind.
Reply:If you can get to the bushing maybe you could save one or both parts by using a slitting disk. You could get lucky and just spead the bush, tack it and weld it back up when you re-assemble.Like the above guys I have nothing with the possible exception that pins pull easier than they push. If the pin is small, then drill & tap and use a slugger. If it's large you need a hollow bore or twin-ram cylinder with the various things needed to get a straight pull.Matt
Reply:ive had bad experiences with ss bolts and nuts galling so you could not get the nut off once it was tightened..cut and grind..
Reply:The only other thing I can think of is to try and straighten the bushing and try pressing it out again.  But your probably SOL.Have we all gone mad?
Reply:Well, if the shaft is stainless steel and the bushing is carbon steel it is very easy to remove the bushing from the shaft.  An oxy/acetylene cutting torch wont touch stainless steel.  Simply cut the bushing off the shaft.  I do this all of the time with various other parts threaded on to stainless steel rods.  With practice you'll be able to cut a part off a threaded shaft without even touching the threads.Galling is your enemy here.  If something is stuck to stainless steel it is probably galled.  Once they're galled they're stuck for life.  You can try to pull or turn the galled component but it's just going to tear metal away from the stainless steel.  It's best just to cut.Heating to remove stainless steel parts that fit over carbon steel parts is a no-brainer.  Heating to remove carbon steel parts that fit over stainless is difficult.  Most stainless alloys have a coefficient of thermal expansion that is 50% higher than carbon steel.  So, if the parts are of uniform temperature the stainless steel will have expanded more than the stainless and be even more stuck.  The trick here is to heat FAST.  Use the biggest rose bud you've got and heat until the steel glows red.  Don't give the heat time to soak into the shaft.  You have to push fast, too.  If you get it half way off and it gets stuck again as the heat soaks down to the shaft you'll have to allow the parts to cool completely and then start again.Last edited by 76GMC1500; 07-12-2010 at 10:41 PM.
Reply:If hes cutting through steel, then the flame will easily cut into the stainless.  Once the cutting reaction begins it will blow enough iron into the stainless to continue the reaction.  Ive cut stainless plate with a torch and 3/16 steel rod.It can be done, I just dont want the OP to think he can blast away and not risk harming the shaft.  Use caution just like it was steel. (if you intend to try and save the shaft)Have we all gone mad?
Reply:I agree with Moonrise - You should have used Anti Seeze - with Nickle and if you had to weld with something inside - you should have stuck a piece of brass inside of the hole and not the stainless steel part you wished to retrieve.