welding cast iron

[jimco]

I have an older mill vise that was given to me(price was right-free) it was over tightened and cracked. It was brazed and a good job done on it but it crack again. I plan to use it for rough milling not precision grinding if you know what I mean, so could I lay some C.R steel next to the cast and ac weld it using nickle rod?

[Weldtutor]

Welcome to CNCzone

so could I lay some C.R steel next to the cast and ac weld it using nickle rod?

Certainly it is possible to repair as you suggest.

As to strength & serviceability afterward it would depend on things such as where the crack is located, weld deposit, joint preparation, heating & cooling etc.

If you are suggesting lapping a piece of CRS over the crack & welding around it, that might work if the crack is in a thin section of the casting.

Repair of a crack on thicknesses over 1/4" is probably better done by vee-ing out the fracture & replacing it with weld metal.

Most nickle alloy electrodes can join cast iron using AC.
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Above comments are worth what you paid for the casting.

[Geof]

I have an older mill vise that was given to me(price was right-free) it was over tightened and cracked. It was brazed and a good job done on it but it crack again. I plan to use it for rough milling not precision grinding if you know what I mean, so could I lay some C.R steel next to the cast and ac weld it using nickle rod?

Yes but it will probably be a waste of time. You might find some rods that are supposed to be suitable for stick welding cast iron. Provided you don't put any load on the weld it will probably stick. The only effective way to repair cast iron and as you have discovered even this is not totally reliable is brazing.

[holbieone]

my best advice would be to find another vice

welding cast iron is never as strong as the original

i had one crack on me at the back jaw

i was able to mill a flat then a key way ,drill two holes and bolt a piece of steal as the back jaw

[jimco]

Well thanks for your input I figured that would be the answers I would get, but I was hoping somebody mite have come up with a new way. I also though like "holbieone" that my best bet would be to try and fasten it down to a plate under it. So THANK guy's

[greg b]

Try veeing out the fracture in the vice as stated elseware in this thread and then pre heat, try using 99% nickle rods .I have an old vice I welded about ten years ago and it still seems to be hanging in there.Sometimes it can be an advantage to peen the weld as its cooling .good luck greg b.

[andrew_g]

I use to work in an engineering shop - we would vee out, pre heat and use a "weld all" rod, then cool down in a bin of lime - it takes 12 hrs to cool down.

Only thing - it will work or it wont.

[Madclicker]

When I was first in welding tech school, 32 yrs ago, our first term course work included a class on all oxy-acetylene work. In it we were required to braze and weld cast iron. To pass, your weld had to pass a destructive test...ie put it in a vise, whack it and have it break other than in the weld.

If I remember correctly, the cast iron rod was about 1/4" square and we used a carburizing flame. I guess now the flame choice was because of the high carbon content of the cast iron, but don't remember being told that at the time. I do remember that preheating was a real priority as it was in just brazing the cast iron.

Never welded any cast iron other than in that class, but it let me know it could be done with good results.

[jimco]

Just an up date, I did weld it with nickle rod with an ac buz box welder. I preheated then layed several 1/2" rods in the coolent runs on the top side plus I two 1/4 x 1" x 2" crs on the out side to bridge the crack, turning the vice over it has three ribs case in it so I put 1/2" crs rod in them and welded it, then put it in a lime box to cool. I am pleased to inform you that it seems to be holding and flat, so it's back in use. Thanks for help Jim

[in2steam]

Just an up date, I did weld it with nickle rod with an ac buz box welder. I preheated then layed several 1/2" rods in the coolent runs on the top side plus I two 1/4 x 1" x 2" crs on the out side to bridge the crack, turning the vice over it has three ribs case in it so I put 1/2" crs rod in them and welded it, then put it in a lime box to cool. I am pleased to inform you that it seems to be holding and flat, so it's back in use. Thanks for help Jim

If its truly cast iron you may want to let it sit for some time before you use it alot, iron tends to build up stresses internally after welding worse then other metals, letting it sit without clamping forces on it for awhile is always a good idea. If it breaks depending upon were the weld was it might be explosive if the forces are right never good while parts in a vise.
chris

[weirtech]

here is a turbo housing casting i welded a v-band flange to. i just preheated the housing for a hour or so then used 309L filler at about 150amps on my miller 180sd.
http://i47.photobucket.com/albums/f1...h/DSC07507.jpg
http://i47.photobucket.com/albums/f1...h/DSC07509.jpg
http://i47.photobucket.com/albums/f1...h/DSC07516.jpg

mind you this is no vice and isn't structural at all.

[NC Cams]

There was a lot of production welding of cast iron to tubing back in the old flat tappet camshaft days - that is how GM used to make lifters inexpensively.

Here are some tips that work well for very reliable, production suitable welding/brazing efforts:

One of the problems in welding iron is that it has ever so much carbon. This makes it rather difficult to weld and/or braze. One trick is to etch the surfaces of the iron to be welded with chromic acid. This will etch out some of the carbon thus making it possilbe for the braze to better wet/adhere to the surface.

Another trick is to electroplate the surfaces to be joined with bronze (preferrably a tin/copper bronze). If you plate about 0.0005" or so, you can then simply heat the parts under heat and pressure and the parts will self fuse together.

HOWEVER, not any tin based bronze will work as too much copper will result in the need to get and hold at 1900 def F or so. With the right alloy of bronze plating, you can reliably and repeatably fuse at about 1500 F with only a short heat soak at temp in a suitable atmospher (as in furnace braze).

Another trick is to flash nickle plate the iron after etching it as noted above. At that point, you can braze with either paste or rod type fillers - again with the proper atmosphere.

For true welding, a 303 stainless wire has been used to form an austenitic (lwo carbon, essentially "soft") weld in the iron. However, precleaning, weld joint preparation in concert with preheating and the use of a suitable atmospher is MANDATORY.

The use of the chromic acid tech in concert with plating and/or the use of a proper filler agent can make a HUGE difference in the weld zone integrity. The need to normalize the weld after the preheat and welding effort (in a suitable atmostphere) can NOT be over emphasized if you want a dead reliable weld.

To simply fuse something together and hope for the best, buzz boxes and not so trick flame brazing with generic brass filler rod can often suffice.