Steel Casting Defects (Cold Shut) - Expert Advice needed

rstocum

Involved In Discussions
#1
I am dealing with a supplier who wants to grind away the visible indications of a "cold shut" on steel castings that they supply to us. Our customers specifications say that "cold shuts" are unacceptable for any reason. The supplier wants to avoid scrapping hundreds of parts. My concern is that a "cold shut" is likely more of a defect than a visual defect. I believe it weakens the casting, and that grinding away the visual effect would only disguise the fact of a compromised casting.

Am I wrong? Is the supplier suggesting something reasonable? I am a machinist by trade, and an engineer by default, not a metallurgist. I need expert advice from someone who really knows their steel castings.
 

gard2372

Quite Involved in Discussions
#2
Re: Steel Casting Defects (Cold Shut)- Expert Advice needed

I am dealing with a supplier who wants to grind away the visible indications of a "cold shut" on steel castings that they supply to us. Our customers specifications say that "cold shuts" are unacceptable for any reason. The supplier wants to avoid scrapping hundreds of parts. My concern is that a "cold shut" is likely more of a defect than a visual defect. I believe it weakens the casting, and that grinding away the visual effect would only disguise the fact of a compromised casting.

Am I wrong? Is the supplier suggesting something reasonable? I am a machinist by trade, and an engineer by default, not a metallurgist. I need expert advice from someone who really knows their steel castings.
Well, to put it bluntly if the customer specifications are No cold shut's and the supplier has these spec's available to them and have a contract with you, then no, they are not allowed.

Did they PPAP/FAI the casting process prior to a production run? Ususally they prove the mold and casting process fisrt on a prototype piece in conjunction with a casting program (Magma) which shows the optimum pouring solution.

Options)

1- Get the customer's deveiation request in writing to allow the supplier to grind

2- The supplier has to eat the costs of the scrap parts and must involve SQA and their process engineers to figure out a solution.
 

Stijloor

Staff member
Super Moderator
#3
Re: Steel Casting Defects (Cold Shut)- Expert Advice needed

I am dealing with a supplier who wants to grind away the visible indications of a "cold shut" on steel castings that they supply to us. Our customers specifications say that "cold shuts" are unacceptable for any reason. The supplier wants to avoid scrapping hundreds of parts. My concern is that a "cold shut" is likely more of a defect than a visual defect. I believe it weakens the casting, and that grinding away the visual effect would only disguise the fact of a compromised casting.

Am I wrong? Is the supplier suggesting something reasonable? I am a machinist by trade, and an engineer by default, not a metallurgist. I need expert advice from someone who really knows their steel castings.
For non-casting process Covers, here is a definitinion:

COLD SHUT
A defect produced during casting, causing an area in the metal where two portions of the metal in either a molten or plastic condition have come together but have failed to unite, fuse, or, blend into a solid mass.


Source: The Metal Dictionary.

Stijloor.
 
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Coury Ferguson

Moderator here to help
Staff member
Super Moderator
#4
Re: Steel Casting Defects (Cold Shut)- Expert Advice needed

I am dealing with a supplier who wants to grind away the visible indications of a "cold shut" on steel castings that they supply to us. Our customers specifications say that "cold shuts" are unacceptable for any reason. The supplier wants to avoid scrapping hundreds of parts. My concern is that a "cold shut" is likely more of a defect than a visual defect. I believe it weakens the casting, and that grinding away the visual effect would only disguise the fact of a compromised casting.

Am I wrong? Is the supplier suggesting something reasonable? I am a machinist by trade, and an engineer by default, not a metallurgist. I need expert advice from someone who really knows their steel castings.
My opinion: Make the supplier remelt new castings and I would also issue a Corrective Action. Have the supplier look at their processes and see if it is a process failure and provide root cause.
 
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michellemmm

Quest For Quality
#5
Re: Steel Casting Defects (Cold Shut)- Expert Advice needed

I am dealing with a supplier who wants to grind away the visible indications of a "cold shut" on steel castings that they supply to us. Our customers specifications say that "cold shuts" are unacceptable for any reason. The supplier wants to avoid scrapping hundreds of parts. My concern is that a "cold shut" is likely more of a defect than a visual defect. I believe it weakens the casting, and that grinding away the visual effect would only disguise the fact of a compromised casting.

Am I wrong? Is the supplier suggesting something reasonable? I am a machinist by trade, and an engineer by default, not a metallurgist. I need expert advice from someone who really knows their steel castings.
What type of product are you producing?

Years ago, I used to be involved in valve manufacturing and cold shuts/cold weld were absolute no no!!!

Technically, you can make a sound casting by welding.

I would ask the supplier to perform pull test on a samples. Let them see the consequence of sending defective material.

I would also ask them to submit xbar/r charts on temp control with every shipment. I am sure they don't have one. Once they start collecting data, the problem will go away.

You need a permanent solution and not a temporary fix.


 

Jim Wynne

Super Moderator
#6
Re: Steel Casting Defects (Cold Shut)- Expert Advice needed

I am dealing with a supplier who wants to grind away the visible indications of a "cold shut" on steel castings that they supply to us. Our customers specifications say that "cold shuts" are unacceptable for any reason. The supplier wants to avoid scrapping hundreds of parts. My concern is that a "cold shut" is likely more of a defect than a visual defect. I believe it weakens the casting, and that grinding away the visual effect would only disguise the fact of a compromised casting.
If the outright ban on cold shuts was "flowed down" to your supplier, then you have your answer already. It doesn't make any difference whether the defects in question actually compromise the structural integrity of the parts or not. Unless you're prepared to ask your customer to accept the defects, and they agree, you really don't have much choice.
 

rstocum

Involved In Discussions
#7
I didn't provide enough information. A little extra background.

For better or worse my employer has gotten into supplier relationships going both ways with China. We buy chinese castings, and we sell finished machined products to China. The relationships are handled by a distributor who also takes care of CAPA, and translation issues.

Whatever the corrective action is (and there will be one), it is not likely to be anything as sophisticated as asking for data.

The customer's spec allows rework in tightly defined situations. If the wall thickness (after rework) is within a certain tolerance, and the cold shut indication is completely removed they can be accepted on a "deviation".

We have used a die grinder to grind the areas back to parent material and are having a lab non-destructive test for micro-cracking. My concern is that the casting is **** anyway. It turns out that there is more than one indication area. I am in a bad spot because shipments will be missed if we can't rework. I really need to know if cold shuts compromise the metal structure.
 

Coury Ferguson

Moderator here to help
Staff member
Super Moderator
#8
I really need to know if cold shuts compromise the metal structure.
Based upon this definition:

Stijloor said:
COLD SHUT
A defect produced during casting, causing an area in the metal where two portions of the metal in either a molten or plastic condition have come together but have failed to unite, fuse, or, blend into a solid mass.
In my opinion, it would affect structure and strength. You have a lack of material joining together which could cause failure under stress. I am not a metallurgist so I could be way off base.
 
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W

world quality

#9
Hi,
I have been dealing with China, and steel casting in low and Medium steel.
In low carbon steel and medium it does effect the fatigue strenght of the material all over.

You can anneal the medium (above 19% C) and control parts after casting.

There is only two compainies that I deal with around Shanghai, that do Xray testing and have a certified lab. The low carbon steel you can anneal but really does not help that much.

One thing that I have found besides Xraying is using a dye penatrent which is good up to 1/8" deep or Mag partice for deeper disconuities. This will help in small pump casting ect.

Just remember the effects of mass will increase in parts above 4" in LC, and
8" in above MC, casting. Hope this is answer for you.

Run the casting thru a wet mag partice belt line at 100% to be safe.
 

rstocum

Involved In Discussions
#10
We are having two representative parts magnetic particle tested on Monday. If they are OK we will be just in time to ship that afternoon. If they are not OK then it is case closed for the supplier.

Thank you everyone for the input.

Rich
 

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