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Important DFT/Tape Adhesion Issue

May 25, 2011

We have a CED coating (E-coating) plant and currently we are facing a problem with one of our customers ....

They are insisting that when a paint specification says 18-32 microns of thickness on a component a reading of 15-16 microns is also not acceptable for low density areas.

The component is square frame which is connected in the middle by a horizontal cross bar.The cross bar is getting low thickness i.e about 15-16 microns against the requirement of 18 microns.

We are insisting that five readings should be taken over the entire component and an average should be taken and if the average reading is more than 18 microns then the component should not be treated as rejection.

Please comment on this.

Another issue is the customer is insisting on checking Adhesion using Tape Test on weld areas and embossments.

Please comment on this as well.

Also it would be really helpful if I could get some supporting documents which could help me and my customer to identify and solve the issues.

Janhavi Sindhu
Plating Shop Employee - Pune, Maharashtra, India

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A chain is as strong as the weakest link. I did not pen that but that is absolutely true. If the DFT is lower than the minimum prescribed by the customer then the coating is indeed defective. The customer has given a very wide range for the DFT and there is no reason why is cannot be achieved. The average method is not a norm for DFT inspection.

Gurvin Singh
Mohali, Punjab, India
June 2, 2011