Does anyone know where I can find the acceptance criteria for scratches on base metal ?? We produce parts from coils and have run into a scratch issue that the final part becomes a frame rail for a truck, which is an unexposed application. The customer is telling me that the rule of thumb is that if your fingernail catches the scratch, it is unaceptable. I know this applies to exposed applications but nor for unexposed.
Any help would be appreciated.

Thanks in advance.

Does anyone know where I can find the acceptance criteria for scratches on base metal ?? We produce parts from coils and have run into a scratch issue that the final part becomes a frame rail for a truck, which is an unexposed application. The customer is telling me that the rule of thumb is that if your fingernail catches the scratch, it is unaceptable. I know this applies to exposed applications but nor for unexposed.
Any help would be appreciated.

Thanks in advance.

What do the specifications say? If the inspector has no fingernails, then all gouges would be acceptable :cool:. Rather than throwing a standard in the customer's face, a practice that often backfires, you should try to discuss with them what they actually need, determine whether or not your process as agreed upon in the original contract is capable (renegotiation could be in order) and then put the clearly objective requirements in writing.

Rule of thumb is well in good in some instances, but it's the customer that makes the final call. Check with your customer, they're the best source for an answer to this.

For our product it was typically resolved based on a discussion between the Customer and Sales and Quality. I've recently bitten off all my fingernails, so I'd make a horrible inspector (as Jim indicated). Part of it is a grey area based on what the material will be used for (i.e., no one wants to see scratches on their final product) and if the scratches can impact how the material is processed. We also looked at the depth of the scratches as well as the "scratches per square unit of measure".

At the end of the day, however, it's what the Customer will accept. If they want scratch-free product, you had best make sure their specifications say that on future orders.

Just as an aside - so-called "appearance" items often are rooted in mechanical reality. Scratches interfere with subsequent coatings or platings, creating opportunities for corrosion. Scratches and cracks offer beginning points for structural failure, resulting in disasters as bad as the one plane in Hawaii which literally peeled apart. Other considerations have to do with safety from scratches to workers while handling materials during construction or assembly.

The solution:
Discuss form, fit, and function frankly with each customer. Special consideration can often command special pricing over "standard" pricing. In the words of my grandma, "when life hands you lemons, it's time to open a lemonade stand!"

Friends,

Scratches...

Customer requirement: No scratches.
What is a scratch? How do you define it? How do you verify the presence or absence? What's acceptable, what's not? There must be a clearly defined and agreed upon Operational Definition.

Operational Definition criteria:

The definition must yield a single yes/no answer
It must be understandable by all involved
The definition must be consistent
The method of inspection used to check must be clearly defined and consistently maintained

Get agreement between you and the customer...

Stijloor.

Friends,

Scratches...

Customer requirement: No scratches.
What is a scratch? How do you define it? How do you verify the presence or absence? What's acceptable, what's not? There must be a clearly defined and agreed upon Operational Definition.

Operational Definition criteria:
The definition must yield a single yes/no answer
It must be understandable by all involved
The definition must be consistent
The method of inspection used to check must be clearly defined and consistently maintainedGet agreement between you and the customer...

Stijloor.

Very good guidelines for establishing objective criteria. Anyone who's been involved in any type of metal working will run across a situation like this sooner or later. In stamping and sheet metal fabrication, "sharp edges" is a common undefined "defect," and so are burrs. The key is contract review, and making sure that there are no criteria in the specifications which haven't been objectively defined. Something like "no scratches" on a drawing should be a red flag.

Does anyone know where I can find the acceptance criteria for scratches on base metal ?? We produce parts from coils and have run into a scratch issue that the final part becomes a frame rail for a truck, which is an unexposed application. The customer is telling me that the rule of thumb is that if your fingernail catches the scratch, it is unaceptable. I know this applies to exposed applications but nor for unexposed.
Any help would be appreciated.

Thanks in advance.

Hello Ziggyroo,

I am also using CR & HR coils to produce filter components for the past twelve years,and I've not found a 'single scratchless sheet' so far.Scratches are bound to be formed due to (mis)handling.You have got to decide if the scar formed is deep enough or not.A popular checking method is to use your nail,if it digs in,then scratch has to be buffed;else it is passable.(of course the final decision in the matter lies with the customer).In your specific case, your customer has 'spelt out' his criterion,and you have no way of bypassing it under any umbrella of 'acceptance criterion',something I haven't found so far.Even if there is any such (impossible)standard,you still have to follow the dictate of your customer,period.:(

As Dale Carnegie has rightly said:If you have a lemon,make a lemonade,don't cry for orange juice.

Hope it (does'nt help) but clarifies.

Umang :bigwave:

Very good guidelines for establishing objective criteria. Anyone who's been involved in any type of metal working will run across a situation like this sooner or later. In stamping and sheet metal fabrication, "sharp edges" is a common undefined "defect," and so are burrs. The key is contract review, and making sure that there are no criteria in the specifications which haven't been objectively defined. Something like "no scratches" on a drawing should be a red flag.

Hello Jim,

You are right about "sharp edges" & "burrs" being common defects,in stamping and sheet metal fabrication,but they are 'well defined' in drawings as well in the control plans.So far I have never seen "no scratches" on the drawings from my customers,but again,if so defined it actually is a red flag.

Umang :agree1:

Hello Jim,

You are right about "sharp edges" & "burrs" being common defects,in stamping and sheet metal fabrication,but they are 'well defined' in drawings as well in the control plans.Umang :agree1:

The control plans are irrelevant to the discussion, because they should reflect the customer requirements (in this instance). As far as sharp edges and burrs being defined on drawings, sometimes yes and and sometimes no, and usually they're not. When I say "defined," I'm referring to defining (in line with Stiljoor's guidelines) the acceptance criteria.

The control plans are irrelevant to the discussion, because they should reflect the customer requirements (in this instance). As far as sharp edges and burrs being defined on drawings, sometimes yes and and sometimes no, and usually they're not. When I say "defined," I'm referring to defining (in line with Stiljoor's guidelines) the acceptance criteria.

I am in full agreement with you Jim,but my own experience with my customers viz: Donaldson & Purolator (to name a few),exclusively define on their drawings as "no sharp edges or burrs".This has become a practice of late,to avoid any problem caused by these defects.The dictats of the drawings are translated in the control plans to ensure conformity,which is further freezed in the PPAP.

Experience differ from person to person,time,place and requirement.Hence there are no absolute rights or wrongs.One person's food may be another's poison,and vice-versa.

Umang :notme:

Thanks for everyone's replies on this matter. All points are well taken.
Everyone (customer & steel mill) has stated that will any hot rolled product you will get scratches. That is just the way it is, yet the customer wants a scratch free surface.
Since the customer has requested no scratches, we have no choice but to supply them parts that ar escratch free.

Once again, thank you all for your comments.

:thanks:

Thanks for everyone's replies on this matter. All points are well taken.
Everyone (customer & steel mill) has stated that will any hot rolled product you will get scratches. That is just the way it is, yet the customer wants a scratch free surface.
Since the customer has requested no scratches, we have no choice but to supply them parts that are scratch free.

Once again, thank you all for your comments.

:thanks:

Hello ziggyroo,

Quote: "Since the customer has requested no scratches, we have no choice but to supply them parts that are scratch free."

That remains to be seen. Every manufacturing process has its limitations. The purpose of "review of requirements related to the product" is to assess the feasibility of what it is the customer wants from you. If you accept the "impossible", you may lose your behind on this program. It's OK to push back a little... Customers are not always aware of what can and can not be accomplished. I learned that "customer education" can have a tremendous ROI. Don't give up yet.

Stijloor.

Hello ziggyroo,

Quote: "Since the customer has requested no scratches, we have no choice but to supply them parts that are scratch free."

That remains to be seen. Every manufacturing process has its limitations. The purpose of "review of requirements related to the product" is to assess the feasibility of what it is the customer wants from you. If you accept the "impossible", you may lose your behind on this program. It's OK to push back a little... Customers are not always aware of what can and can not be accomplished. I learned that "customer education" can have a tremendous ROI. Don't give up yet.

Stijloor.

Very true. :agree1: If the problem of scratches is inherent in the process, then the customer isn't going to get better results by going elsewhere. What they're likely to find is other suppliers who will accept the work and worry about the consequences later, or those who will take the "no scratches" requirement into consideration and quote accordingly. Either way, they're probably no better off than they would be if they stayed with you.

Hello Ziggyroo,

I have earlier stated in my posting,that it is impossible to get a scratchless sheet,a fact you have confirmed on the basis of 'feed back' from your suppliers;there fore,you have very limited options open to you.

Since your customer has categorically implied,that he wants "no scratches" on the material;you are roped in to comply or get out.:mad:

The only option you are left out with it is,to comply,or else loose the order.A situation I've gone through more number of times I care to remember.:argue:

No one wants to loose an order,so the pros & cons of complying;have to be evaluated.:truce:

If you desire to comply,then you will have to add two additional costs in the process,1.segrigation of scratched components.2.Buffiing of the scratched components.:cfingers:

Ideally and normally,this additional cost should be bourne by the customer.But if the customer is reluctant(which is more often than not),then you will have to review your cost accounting and economics;towards absorbing the additional cost at your own end. :frust:

Hope the analysis helps.

Umang