Repairing cast iron casting.

[Herbiev]

Hi all. In a careless moment I dropped my Quorn t&c grinder breaking one of the castings. Just wondering about the best method of repair. Tig with stainless rod, brazing or silver soldering. The casting supports the work head. Tia Herbie.

 

[ruzzie]

Hi
I have had success brazing a casting back together, I have never tried to silver solder but I have seen rods for stick welding cast iron.

A bit of imfo from BOC
http://www.bocworldofwelding.com.au/media/pdf/WELDING CONSUMABLES-Cast Iron.pdf

Cheers
Paul

 

[hi speed scrap]

Hi Herbie,
I repair a lot of CI castings, incl exhaust manifolds etc.
for that I would do as follows,

V out area you are welding
heat casting and let cool (burn out oil etc)
regrind vee area slightly so shiny clean
Jig casting up to hold in position
Preheat the the casting (evenly all over)
Weld with AC arc and high nickel rods (ie cast craft 100 or equiv)
Weld a section and peen thoroughly with point of chipping hammer.
Wire brush clean.
weld ,peen and brush small sections until complete, as quickly as
possible.
cool slowly.
There are other ways to do it, but in this case thats what I would use

Dave

 

[Swifty]

I'm with "high speed scrap" on the method. Definitely need to burn out the oil in the casting, and have also used cast iron welding rods, I think that I have some cast iron filler rods somewhere as well, for use with an oxy/acetylene set.

Paul.

 

[gus]

I am with "high speed scrap's '' method which was used in the Singapore British Army 40 Base Engine Workshop where I was attached for 2 months during trade school days some 52 years ago.
A make shift oven was built with fire bricks n topped up with heat resistant asbestos and steel plate to preheat an army truck engine exhaust manifold with large oxy-acet burners. Took three hours to preheat before using very long stick rods to weld. Was quite a sight and experience for a 18 year old trade school kid.

 

[moya034]

hi speed scrap posted the correct method for welding cast iron.

That being said, I would urge you to consider brazing instead. It's typically just as strong and will be easier to pull off correctly if you aren't experienced with welding cast iron. Preheating and cooling slowly is still advisable for brazing, but is less critical as compared to welding.

The reason for the even preheat and slow cooling is to keep the brittle cast iron from cracking due to the internal stresses created from heat related expansion and contraction. Keeping a normalized temperature reduces the chance for catastrophes, but does not eliminate it.

If you do decide to weld the cast iron, I would do some practice on some scrap to get your technique down.

 

[kf2qd]

Cast iron welding is not all that difficult if you have experience with oxy-fuel welding of steel. The big difference is that you need to keep the casting hot the whole time you are welding. Depending on the size of the part for the size of the heater.Plenty of flux and flow the cast iron rod in and make it bigger than the original cast area so you can grind it back to shape when it cools overnight. A box of powdered lime with about 9X the volume of the part you are repairing is good for a slow cool process.

 

[chipenter]

I have silver soldered cast iron the break must be shiny it won't stick to the grey , a cup wire brush in an angle grinder does the job , and has the advantage of locating the break in the right place and leave a smaller fillet .

 

[Herbiev]

Many thanks to all for the replies. I guess the key is to get some practice in on some scrap before tackling the real thing. Will keep you posted.

 

[Maryak]

Hi Herbie,

Would you like me to pop in and give you a hand, I also have some castcraft rods. Just say the word and I'll come up, ( as long as the cofee's hot

Best Regards
Bob

 

[Herbiev]

That's a deal Bob. Many thanks.

 

[Septic]

I've welded thousands of cast machine tool parts using MMA electrodes specially formulated for malleable cast iron and while it does require a little more care than mild steel, the result is extremely strong and the strength of the surrounding material suffers very little compared to some techniques... A 120 ton press-brake I welded in 1974 after it cracked a main section is still shaking the ground in East London to this day as far as I am aware...

 

[John Rus]

I have successfuly soldered cast iron with Muggy Weld, I used the paste and put the parts together without V grooving. Heated the parts with a propane torch and the solder just flowed in. If you have thicker parts you may have to heat the parts in the oven so the heat doesn't get wicked away before you can solder them.

Just another method too consider,
John.

 

[Septic]

I As John Rus suggests, "muggyweld" and many other low temperature, alloy/cast, solder compounds are surprisingly good for repairing broken castings in non-critical applications.

There are also some excellent engineering glues and fillers which are very good and can also be machined if required.

 

[moya034]

In all reality, to recommend the best method of repair we would need some pics of the part and failure, with some basic measurements.

 

[Herbiev]

http://www.homemodelenginemachinist.com/photo/quorn-casting-737.html
Hi Moya. This is the casting. It mounts on the vertical shaft of the Quorn and is part of the work head assembly

 

[Herbiev]

Just want to say many thanks to Bob for stopping by this morning and doing a fantastic repair job on my casting. The great thing with forums such as ours is that you get ideas from around the globe and meet like minded people in your own neighborhood. Thanks also to all who replied.
Herbie the happy moderator.

 

[Maryak]

Your very welcome Herb and the coffee was great too.

Best Regards
Bob

 

[///]

Onya Bob!

While all the advice was great, nothing beats having someone experienced do it properly for you and in a fraction of the time.
And you have learned something new, hopefully

 

[goldstar31]

I'm going to fly in the face of the opposition. The reason is because I have a Quorn and I have seen 'other Quorns' which were made by local modellers. there is NO reason whatsoever why a Quorn part cannot be fabricated from mild steel sections. Frankly, if that had happened to mine, I would have glued and then put two steel pins in it. The load on a Quorn is so demanding that Chaddock thought that a cut of a quarter of a thous was a whopping cut!

I once did an awfully tricky mend on a AGA type fireplace where the replacement grates and indeed the whole gubbins was not only obsolete but dated back to the Dodo. I built it up by shoving white hot arc mild steel welding rods into the remains and building up on the new mild steel.

Oh and a bit of adding insult to injury( perhaps), I went off for a motor to drive a Quorn or whatever. The 1/6th HP 2880 variety recommended. It came home fastened to a Stent- the 'short wheel base' variety and I was in a rush. dumped it into the back of the little car-- and found that it was --fabricated from mild steel sections. I suppose that I got my hundred quid's worth.

I'll get me coat

Norm