Who was TIG welding magnesium?

[67L36Driver]

And, what are you using for filler rod?

Bead goes 'plink' and parts company as it cools.

I have my Homelite 2000 crankcase at a motorcycle shop and they can't get their rod to stick. Had it at another shop for five weeks but they didn't try so I moved it to the 'cycle shop.

 

[mweba]

srcarr52

 

[3000 FPS]

I have been using AZ92A magnesium filler rod with a Tig.

It has worked on everything but one piece which I believe was a muffler cover for a Homelite 1050. There was something about the alloy of that piece that I could not get the magnesium rod to stick to. I tried aluminium rod also and it would not work. I did test the piece for magnesium and it seemed like it was magnesium but I never did get around to finding out why it would not weld and I have welded up quite a few magnesium parts for saws.

 

[srcarr52]

I think it was probably me you are thinking of. I use Harris AZ92A rod. Here is the video I've posted before.

[video=youtube;oFnhCd9PHWc]https://www.youtube.com/watch?v=oFnhCd9PHWc[/video]

 

[nmurph]

I get the welding department here at the college to weld saws for me. As a matter of fact, I picked up two cases that were welded yesterday. I bought the AZ92A rods from Ebay (the only place I could find them where I didn't have to buy 1lb for $150. The key is to have a very clean surface. I grind away the old metal about 1/2" around the weld to expose fresh, clean magnesium. I can ask about settings if needed, or Shaun can fill you in.

 

[srcarr52]

I get the welding department here at the college to weld saws for me. As a matter of fact, I picked up two cases that were welded yesterday. I bought the AZ92A rods from Ebay (the only place I could find them where I didn't have to buy 1lb for $150. The key is to have a very clean surface. I grind away the old metal about 1/2" around the weld to expose fresh, clean magnesium. I can ask about settings if needed, or Shaun can fill you in.

Yes, proper cleaning is a must. Everything I weld get a trip through the jet wash and bead blasted before welding.

I bought my welding rod off ebay. Most welding supply places will only sell 3 lbs at a time, mcmaster sells in 1/2 lbs quantities but it's expensive.

As for tig settings treat it the same as aluminum.

 

[bikesandcars]

Magnesium absorbs oil over time, the older magnesium xmission cases, oil pans, etc on race cars are actually known to weep depending on the quality of the magnesium and casting.

My opinion is that the surfaces are still contaiminated. You will likely need to bead blast the surface as well as use liberal amounts of carburetor cleaner as well as heat to get the surface clean enough. It might never get clean enough.

I don't know enough about welding magnesium itself to suggest a good "dirty" rod or other techniques, just my opinion really.

 

[3000 FPS]

I have found that sandblasting the part works pretty good for cleaning, but like what was mentioned the castings can be pourous and soak in oil. I have had parts that I welded up to 3 times in the same spot because of pitting caused by contaminants.

 

[srcarr52]

Magnesium absorbs oil over time, the older magnesium xmission cases, oil pans, etc on race cars are actually known to weep depending on the quality of the magnesium and casting.

My opinion is that the surfaces are still contaiminated. You will likely need to bead blast the surface as well as use liberal amounts of carburetor cleaner as well as heat to get the surface clean enough. It might never get clean enough.

I don't know enough about welding magnesium itself to suggest a good "dirty" rod or other techniques, just my opinion really.

I have an industrial jet wash that has some nasty chemicals and lots of heat to bake out most of the oil. You can also do what is know as a cleaning pass where you weld a small bead or just melt the face material allowing the contaminates to come to the surface. Then you grind and blast the surface again.

Also, never use a steel wire brush on aluminum or magnesium. It will leave rust impregnated in the material. Use a stainless brush that has never been used on anything besides mag or al because it can carry particles from it's past use.

Same goes for grinding wheels/belts. Do not use anything that has ground on steel or other things on mag or al to be welded as it will imbed tiny bits of it into the material to be welded.

This is why it's best to use a carbide burr and a bead blaster to do the prep. work.

 

[67L36Driver]

Thanks for the help fellas.

I see where we were using a steel rotary file and wire brush is likely causing some of the problem.

I'll make a visit in the morning and see if we can do better.

Carl.

 

[nmurph]

The steel was likely you problem.

I grind the spot to be welded the night bf and take carb cleaner with me to the shop. We are careful not to touch the bare metal and clean it with carb cleaner right bf it is welded.

 

[srcarr52]

The steel was likely you problem.

I grind the spot to be welded the night bf and take carb cleaner with me to the shop. We are careful not to touch the bare metal and clean it with carb cleaner right bf it is welded.

I use lacquer thinner as carb clean and definitely brake clean can produce some very harmful vapors when heated.

 

[machinisttx]

I use lacquer thinner as carb clean and definitely brake clean can produce some very harmful vapors when heated.

Brake cleaner will produce phosgene gas when heated. It's really, really nasty stuff and can kill in even small quantities.

 

[3000 FPS]

Thanks for the help fellas.

I see where we were using a steel rotary file and wire brush is likely causing some of the problem.

I'll make a visit in the morning and see if we can do better.

Carl.

Since you are working on a Homelite I am personly interested in your out come. Thanks Roger

 

[imalogger]

I'd J-B weld that:msp_biggrin: I've been really amazed at what that stuff will do..

 

[67L36Driver]

I'd J-B weld that:msp_biggrin: I've been really amazed at what that stuff will do..

It may come to that.

I need to check on their progress tomorrow. They may have chi%#@$ canned it by now.:msp_scared:

 

[King opines]

If you are welding a crack in a tank or cover, it is a good idea to drill small holes in each end of the crack, this will relieve the stress from welding and keep the crack from returning after the part has been welded up. As others have posted, cleanliness is an absolute must when welding alloys such as Aluminum and Magnesium. There is also a cleaner out, we use it from time to time, that is a mild acid, it's called alumabrite it can be used to clean the area around the weld, make sure that it is used as prescribed and wash off well before starting an arc. Be extra care when grinding magnesium, the grinding "dust" can be extremely volatile and once ignited can only be extinguished with the proper chemicals.