Is it possible to tig pot metal?

The tailgate latch on my 94 Mazda/Ranger pickup broke today..so as an experiment, I tried to tig weld the broken parts, not figuring it
would work..but needing to try anyways. I figured it was pot metal as it appeared to weigh a bit more than an equivelent mass of aluminum.
So I set up for aluminum, and started buzzing away..and it melted and slumped about the time I could start to see a tiny bit of liquification. Blooosh. Shrug I did start low, with a 1/16" tungsten, and it went bloosh about 25 amps. The piece was about .250 thick, and about .375 wide, 1" long, placed on a piece of copper for a backing.
If Id had some zinc rod, I could have tig brazed it I suppose, but didnt and none was available in the area.
Any suggestions for the next time this sort of thing comes up? Besides a new latch from the dealer of course <G>
Gunner
"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown
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Solder it instead. A "Lumiweld" kit should be in every toolbox for this sort of repair. It's easy, it's lower temperature (less collateral damage) and it's as good a repair as pot metal will ever need.
"Pot metal" is relatively old, dating from the late '19th century when zinc metal became cheap (zinc is surprisingly hard to extract and remained expensive for a long time). However this metal was never a success as it only has a lifetime of a few years, before distorting and cracking. The cause of this is intra-granular precipitation of impurities, mainly iron, and there's nothing you can do to stop it. Even vacuum or deep-freezing won't help.
Zinc didn't really take off in die-casting until the development of Zamak alloy, a high-purity zinc (99.99%) with a controlled amount of copper and aluminium, and little else. This only took place in the '30s, owing to US developments of zinc smelting . The UK didn't use this same zinc process, but did license the diecasting alloy as "Mazak", based on a 99.95% pure electrolytically-refined zinc.
Early diecast toys are now extremely rare (and thus valuable), largely because of this warping and cracking problem with potmetal. Once Dinky started using Mazak, they survived far better.
So if you try to weld Zamak, you have a few problems to deal with:
- It's a low melting point alloy, and you're at it with a hot torch. That's always going to be a high-skill and risky task - the solders are just easier.
- Zinc is a pain with any hot process, because it vapourises so easily. You might not melt the whole piece, but you can easily damage the surface.
- If you do fusion weld on zinc, then the weld pool is likely to have poor metallurgy from impurities. Expect cracking problems in a couple of years - this may or may not be a problem for you.
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Gunner wrote:

Babbitt casting ? - Create a form around it and flow in some junk zinc rod metal or Al.
Go to the junk yard... :-)
Martin
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On Wed, 13 Jul 2005 21:24:51 -0500, "lionslair at consolidated dot net" <"lionslair at consolidated dot net"> wrote:

Babbitt is rarely cast (on its own) and doesn't have either zinc or aluminium in it. It's not the same thing as "pot metal".
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Andy Dingley wrote:

I thought that the casting was Babbitt casting. Not the metal. I don't do it but it has been here for many years. e.g. do a Babbitt casting not a seal in some way with babbitt metal. Some metals might be called babbitt metal.
The tease to Gunner (a good friend) was to build a form around it and pour in.
Martin
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On Thu, 14 Jul 2005 22:23:21 -0500, "lionslair at consolidated dot net" <"lionslair at consolidated dot net"> wrote:

Indeed. <G> Babbitt is the generic name for a host of alloys, generally lead based with some largish fraction of tin. Others under the same "family" are nickle/tin and even the rather odd nickle/lead
Its been used for centuries (usually the lead/tin) for bearings. Other uses is for affixing cables to nibs and end joints.
Btw..give me a call on those surface grinders
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
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Ok - Gunner cleared it up. OBTW - Tin lead either 100% or in various alloys are soldering alloys also. So one could go to a electrical 'house' and buy or order pounds of each. This might save $ or English '#' (sorry for the lack of font) - when buying the 'right' stuff from some 'expert' company...
Martin
Gunner wrote:

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wrote:

Centuries ? Seems rather long - I'd have guessed at two centuries, tops. Anyone have a good source for a history of Babbitt ?
I'm assuming that Babbit (bearing metal inventor) was no relation to Tabitha Babbitt, the Shaker who invented the circular saw blade around 1810.
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On Sun, 17 Jul 2005 11:14:54 +0100, Andy Dingley

http://www.americanbabbittinc.com/history_of_babbitt_bearings.htm http://en.wikipedia.org/wiki/Babbitt_metal
You appear to be absolutely correct. Well done Sir! I do indeed stand corrected.
Gunner
"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown
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Before the end of the 18th century I just couldn't think _why_ anyone would invent Babbitt bearings. Before that date, and the high-pressure steam engine, machinery just didn't rotate fast enough to need it. Wood isn't a bad bearing material, if you use it right, so long as the speed is low.
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Just like putting icecream in the microwave to warm it. I usually attempt to repair white metal or pot metal with a small propane or butane torch. You need casting sand or similiar to form a dam, to keep the melted metal from running away.

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wrote:

Thanks guys. Next time something like this comes up..Ill make up a mould and do it that way.
Gunner
"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown
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