I have a magnesium quickchange with some tight bearings that are in there, I was thinking of putting freon or something on the bearings to try and shrink. What does magnesium do with cold applied will that just shrink as well, I'm afraid to put any type of heat on the magnesium section......any ideas?
you should be fine with a heat gun or electric range....just no open flame. ALL metals expand when heated and contract when cooled...just at different rates. All you need to do is heat the outer piece and cool the inner. you don't need it to 5 million degrees to work. I had a clutch basket I needed to heat and cool on my old cr250.....just popped the basket in the freezer for a 15-20 mins and tossed the gear on an electric range for 5 mins. they just dropped together with no problem. can you get the housing in an electric oven? maybe a local powdercoater could help you out. Mg Thermal expansion rate 26.1x10^-6
I know when I get cold enough, I turn blue and lose my bearings...so maybe your onto something!!! So, you can't even weld near Magnesium? The old weld on the bearing race to shrink it trick?
I've seen old magnesium wheels, blower cases, and quick changes that have been TIG welded before, so I know it's not exactly right that you can't get heat near them. The problem with it igniting is with small pieces, such as shavings or filings. You could heat the whole case with a torch as long as you don't have anything nearby that could ignite it. But to be on the safeside...don't use a torch. Since your problem is that you need to REMOVE the bearings, not install them...I think the welding on the bearing race trick might work. I wouldn't use a MIG though, since it has too much spatter. If you can get to the backside of the bearing, you might try to grease the **** out of it with penetrating oil for a few days, then take the housing to someone with a press. Support the backside of the case around the bearing, and apply pressure directly to the bearing race from the other side. Good luck...it's probably going to be tough to get it out.
Tell me about it. That stuff is DEADLY!!! Thank God I tought my WIFE to weld...Hahahaha I was figuring a few quick "buzz box" p***es on the steel race...BUT I certainly CAN'T recommend it because I have zero experience with Magnesium. So your saying the Magnesium will smoke up and kick your ***? Sounds bad...
Six, I can remove the bearing .call me,easier than you think just put it in a steam cleaning tank bearing genrally fall out.
my bad I though you were trying to put them in. if it will fit in an oven I would try that.the Mg will expand more than the steel will adn it should release it. is it nice and clean?
it's not that magnesium lets off g***es when welded it is that it burns, very hot and is virtually impossible to put out once started. I believe the correct way to weld it is to do it in the absence of oxygen, like in a purged cabinet.
We've got a local import machine shop that welds magnesium all day every day. They'll TIG weld anything you want to pay for on magnesium. I think the secret is what B*** said, not allowing small shavings to catch fire. By the way, I'm a fireman for a living and magnesium burns like hell. We just have to let it burn itself out when it does catch fire. Water only makes the fire worse (it pops and explodes).
It's actually reasonable easy to weld. It's very common to do on VW engine and trans cases. Like B*** said, it's the shavings, filings, and dust that will go up and ignite everything else. It's not that easy to get a large chunk to light. I've heated many a Mag case with my propane torch with no ill affects. I wouldn't use an O/A torch on it though. To Tig weld it, you have to get it hot enough to melt, but not so hot that it lights. Like 60's Style said, a purge cabinet helps too. Not something that I would try myself, but it's common enough that a good welding shop could handle it.
In the Navy when an aircraft blew a tire upon landing the mag wheels would occasionaly catch fire, the only thing that would put them out was PKP.. I think the 'absence of oxygen' is the ticket... PKP is also known as purple K powder. The ingredients used in PKP are non-toxic. When PKP is applied, a dense cloud is formed in the combustion area that limits the amount of heat that can be radiated back to the heart of the fire. Fewer fuel vapors are produced due to the reduced radiant heat. The dry chemical PKP extinguishes flames by breaking the combustion chain.
Magnesium fires... 1. find VW shop. 2. beg owner for a couple of halves of dead cases. VW guys blow 'em up alla time. 3. buy beer. 4. invite a buncha buddies to go camping. 5. Go camping. 6. lite bonfire. 7. drink beer. 8. when beer is half gone - throw cases on fire. 9. finish remaining beer while watching very hot and colorful fire. ****! It's my turn to get the cases for this weekend's fire...
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