Steel Casting Defects (Cold Shut) - Expert Advice needed

[Wes Bucey]

Off topic? - Maybe, but still pertinent!

No scolding here, just a comment. The situation here is fomented by the lack of complete Contract Review and subsequent assurance by all concerned parties they know and recognize what constitutes a nonconformance and allowable "repairs."

As an owner of a contract machining company, I played a lot of CYA when a customer wanted to dictate a source of supply for ANY material (casting, forging, bar stock), simply because so many purchasing departments were fixated on PRICE rather than QUALITY. Often, we simply refused a job if the suggested/dictated supplier didn't measure up to our own standards.

If you need an interpreter just to "talk" or write to a supplier, how can you possibly be sure the supplier has a complete understanding of what your requirements are and how to conform to them?

Frankly, the whole deal starts to smell like melamine in pet food - somebody is cutting corners and the perpetrators are hoping a little grinding will make the issue go away (like painting walls gray to hide the grime.) Good control over the casting process can easily reduce or even eliminate the instances of cold shut on most simple castings. If the casting isn't simple, the manufacture of a good one may simply be beyond the capability of the current supplier. It would not be the first time an inept supplier promised more than he could deliver.

 

[Kevin H]

If it's a true cold shut, I'd worry about weakened wall structure that might erode prematurely or fail catastrophically depending on the pressure and media these valves experience in service. Magnaflux and dye penetrant are good methods to check for clean-up, but still might not guarantee valve quality.

Funny, I recently had a short stint of employment at a cast iron manufacturer who casts ductile and gray iron castings in the US. They entered into a supply agreement/outsourcing agreement putting them between the US customer and the Chinese foundry as a middleman. The original trial castings supplied were good quality ductile iron. The ones we ran into during my tenure were a mystery - our customer complained regarding machining, and when we checked, we'd see good quality ductile next to good gray iron - definitely not decomposed ductile iron. Our best guess was possibly using gray iron scrap to cool a ladle of ductile iron, leaving remaining fingers of gray iron in a ductile casting. We were close to shutting down the customer's pump line (automotive related) for lack of castings.

The customer's purchasing agent had secured his bonus for outsourcing castings to China and moved on before the problems hit. I've no idea how this worked out, as I returned to my prior employer (the situation I inherited did contribute to my decision to return when I got a call from them asking if I was interested in returning.)

 

[Stijloor]

<snip> The customer's purchasing agent had secured his bonus for outsourcing castings to China and moved on before the problems hit.

A classic example of "what's rewarded gets done" without regard to the unintended consequences. :mg:

Stijloor.

 

[Caster]

, we'd see good quality ductile next to good gray iron

Wow, if they could do that on purpose, they could get rich!
Maybe it was actually elegant engineering - a dual phase structure?
Just kidding. If I set out to do that on purpose, I'm not sure I could!

1) lack of complete Contract Review and

2) know and recognize what constitutes a nonconformance and allowable "repairs."

3) fixated on PRICE rather than QUALITY. .

Wes, you beat me to it.

A topic near and dear to my heart as the foundry I work at gets ready to close in the face of low price offshore castings, brace yourself while I unload.

1) Failure of contract review indeed. This is just typical boilerplate text by the buyer to trap the unwary seller. I was trained to reject anything that said "no" or "none" in favor of suggesting a measurable level. Things like no leaks, free from harmful defects, sound castings, no cold shuts are meaningless and should have been raised as issues for negotiation. There is no "NO" in the real world.

The foundry should make the customer design engineer earn his money and call out meaningful measurable specs based on what he really needs, not wishful thinking. And of course the only time you can do this is up front, once you accept an order you are bound by the contract, and an apparently long dead business tradition called "honor".

Gee, maybe those ISO 9000 guys put contract review in there for a valid business reason?

The foundry failed big time in contract review and may have to eat these parts.

2) Friends don't let friend drive drunk. The buyer failed by going for the boilerplate PO gotcha instead of working with the foundry to make a producible casting. So after the buyer makes the foundry recast, do they really think the replacement castings will be any better? The foundry has lost more than it could ever profit from on this order, how keen do you think they will be to make good? So the buyer may win this battle but will surely lose the war.

3) How much has it cost the purchaser to "save money" buying these low cost castings? Please factor in late delivery, all the effort to contain this problem, risk of accepting bad castings with possible long term warranty consequences, dissatisfied customers, and so on.

I double dog guarantee any money the purchaser thought they "saved" on the low price has cost them 10 times the hoped for saving.

Price is not equal to cost, and buyers have to keep learning this over and over and over.

The really sad part is I bet the buyer got a nice fat bonus based on the "savings" and has washed her hands of this quality problem.

This is not a China bash. The best of the Chinese foundries are as good or better than anyone else. Chinese engineers are talented, dedicated and they want their piece of the pie. Good on them, they deserve it.

This is a tirade against low cost suppliers and the people who buy from them. If you get 3 bids within 10% of each other and a fourth at half the price, come on - you know, the low bidder missed something, doesn't know what they are bidding, or has no intention of meeting your requirements.

Of course this has been said here before, much better than I ever could, see Sales the Root of Quality Disasters

 

[Steve Prevette]

My father was a foundryman, so I posed this question of him. He said that cold shuts usually come from an interupted pour, or from the metal being too cold. You certainly could grind off the cold shut, but you'd want to be darn sure that the defect doesn't go all the way through the wall of the casting. Certainly grinding would make the surface of the casting look smooth - but if it was an interupted pour, there would be a crack all the way through the casting.

 

[rstocum]

The cause is now known. The pour was too slow, and it is a true cold shut. The castings are not acceptable by the standards of the end user. These things were all spelled out in the contract review/purchase order process. As noted by a previous poster, we recieved sample parts during the original acceptance process, and approved them. The quality of the latest shipments has changed significantly from the quality of what we approved. There now turns out to be evidence that the distributor's agent in China changed at least one supplier sometime in the last year. Someone mentioned that this is a case of someone cutting corners. They hit that one right on the head. The good news is that the end user is the one who stipulated that these suppliers be used. Their motivation was to save on price. It was stated to us that these castings could be purchased finish machined from China for what it used to cost us just to have them cast here in the US. Other cost factors were not considered. Now the true cost is becoming apparent to them.

 

[Steve Prevette]

Comment from my father:

True Experience that one has to pay the piper for such decisions.

Jerry Call Ex-Director Foundry Society would love to see this if you wanted to share such with him and not show persons involved.
jcall (at) afsinc.org

Bob Prevette