cast iron and steel together

[truckdoctor]

Hi all, I am in need of help, i have to weld together a steel nut to a cast iron boss that is part of an assembly . The thread has stripped and welding is the only way. I have been told by a local engineering company that this type of welding is possible My experience tells me different , but i guess you could say I'm OLD SKOOL what do you folks think ???

 

[brightspark]

cast iron boss or malleable iron boss??

 

[truckdoctor]

The boss is made from cast iron, not sure what the difference would , how can i tell ?

 

[truckdoctor]

http://
Here is a drawing of the parts,

 

[piman]

Hello T D,

yes you can weld mild steel to cast iron, there are rods that will allow you to do that. Also it could be brazed? Why can't the stripped thread be repaired with a helicoil?

The drawing doesn't help much without showing what part is affected?

Alec

 

[truckdoctor]

Thank you for the reply, brazing is out due to the size and it would destroy the hydraulic seals.can't helecoil as its external thread. As long as i know it can be done with special rods thats fine I'll let this engineering co. go ahead.
Thankyou

 

[piman]

Hello Truckdoctor,

now you really are confusing me? if it's an external thread, then why weld a nut on? If heat is an issue then the welding will also put heat into the job, admittedly probably less than brazing but it will get hot.

Also I don't believe that the threaded part you talk about is cast iron, I've never seen a cast iron male threaded component?

Alec

 

[truckdoctor]

Beleive me, a thread on cast iron, with a steel nut thats realy hard, I machined it today and had to use a carbide tip in the lathe. This assembly is a tipical German rubbish piece of engineering that costs in excess of £4000 that comes complete with built in design defects like cast iron threads ??? The nut takes in excess of 4 tonnes force by the two belville washers.
Will take pictures tomorrow and post up of the welding.
Fingers crossed.

 

[piman]

Hello Truckdoctor,

I think I'll need pictures as I don't understand what you are describing. Are you sure it's not cast steel, a completely different material?

Alec

 

[truckdoctor]

Here are a few pictures of what I achieved today, new seals arrived by first class post and the parts were assembled. Here you can see the parts in question, cast iron casing, hard steel nut

Parts assembled and machined to a nice deep groove

Parts now tig welded together and left to cool before four more welds complete the job.Not shown

Looks good to me,sorry the picture a bit fuzzy what do you guys think ?. This cost £35 plus VAT and was carried out straight away by a really good engineering co.

 

[piman]

Hello Truckdoctor,

I understand now, but have to say the boss's thread doesn't look too bad from that picture?

Hope it does the trick anyway?

Alec