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Blackening process on steel part and quality issues

Our production is facing some quality issues on blackening process on steel parts.
First of all, my process WI is as below:
pre-treat (with HCI) > Blackening process ( known as conversion process wf Ebonol M-22) > passivation process ( Cr2O3 etc) > oven ( drying) > ultrasonic process ( remove smut) > oven ( drying) > anti-rust oil = finished goods

Well, now I am facing unplated, bending test fail and erase test fail issues. So far, for past half year, I manage to control my line NC below 20%. But suddenly I am facing >80% NC of finished good although I had 100% made up new chemical bath.

I need some help here. Any good idea to improve my production line please!

Kaka Ryuuichi
plating - KL, Malaysia
2005

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2005

20% nonconforming is such a poor result that it indicates that, even under your most ideal conditions, you have a major problem with your process.

Contact your vendor of all proprietary products to set your line up properly. You should send some of your parts to a laboratory of your vendor to let them process the parts and give you the right finishing cycle.

  
Tom Pullizzi
Falls Township, Pennsylvania

Please make sure the base material and right chemical use.

T.EChuah
- KL, Malaysia
2005