Weld repair in casting

[moebakhtiari]

Dear All,

I have a question about weld repairs on casting parts LCC. When we say weld repair means that if they find any defects then they have to grind out the defect and weld up the area. But the question is, during casting there are many small holes on the surface of part which most of casting suppliers weld up the area (many spot welding areas on part). Is it call weld repair too? My company doesnt accept any weld repair, so I need to know if this process of welding is common in casting.

Thanks.
Moe

 

[metengr]

Any time a welding arc is struck on a casting to add metal, this is a weld repair. There are various types of weld repairs depending on depth and area - major and minor. I will not define these terms because they would be defined in the appropriate material specification.

 

[moebakhtiari]

Thanks for explanation. Is it acceptable if we say, any weld repairs on cast parts (major or minor) is not acceptable? I guess minor repairs in cast industry is very common.

 

[metengr]

Yes, if you are willing to pay for this requirement. Typically, minor repairs are common and are accepted by Purchasers provided the repairs are performed using a qualified WPS, Welder and NDT report.

 

[EdStainless]

Usually castings that have been inspected, weld repaired, re-inspected, and properly heat treated afterward will be just as reliable (if not more) that castings that didn't get repaired.
We used to have limits on the depth, size, and number of repairs.
I would rather have a questionable area fixed than say 'well technically it passed NDT' even though it wasn't very good.

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P.E. Metallurgy, Plymouth Tube

 

[1gibson]

It's not so much paying for the requirement, as it is being willing to suffer the schedule delays. Someone will sell you "no weld repair" without batting an eye. Then when the shop starts machining the castings it will be "give us a deviation and let us weld, or wait another few months for new castings that may have the same problem."

If I wanted quality castings that were realistic to manufacture, I'd specify magnetic particle exam on the raw castings (so the foundry can immediately scrap the real bad ones) and again on a pre-machined components. Depending on the size of the part, leave maybe 0.050" extra material for critical areas. That way if a repair is done, the welding and heat treat won't warp things too much, and you'll still have metal to cut during final machining. If you completely machine to print and then have to weld repair / heat treat, everything will move around and you'll have fit/function problems. Which means more welding/heat treat and more machining.