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Lighting for plating inspection station

2003

In our plant our quality inspectors are always going from place to place to see how parts look in different lighting. We have open spaces and enclosed ones, some parts look good inside but not outside and sometimes the other way around.
We see a haze, or a cloudiness or non uniform chromates and in other areas we don't see them. This is mostly on zinc plated parts with clear chromates, but also with other chromates and other finishes.

1.- Is there a specification for lighting for inspection stations? Is there any documents available that we can check.

2.- What is your lighting recommended for zinc plating and plating in general in inspection stations.

We use fluorescent lights in inspection and metal additives in the plant, but there are many fluorescent type lights; day light, white light, etc.

Please be specific on the type of light recommended.

Thank you very much for your help, Enrique

Enrique Segovia
job shop plater - Monterrey, N.L., México

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W.H. Safranek's, Finishing and electroplating Die Cast and Wrought Zinc [affil link on Amazon] published by the Zinc Institute in 1973 includes an outstanding chapter on inspection and lighting for inspection. I recall that he also wrote a free-standing booklet on design of plating inspection booths, that I once had. But having had it and finding it are two separate things. The point is that the papers have been written, they are out there, but finding a copy may take time and effort.

In brief, one good idea was 10-20 percent of the light coming from a point source (high intensity lamp) and the balance from diffuse overhead fluorescent, for a total of 150-200 foot candles. One useful and proven idea was "striped" lighting which can be obtained in several ways, but an easy way seemed to be to paint black stripes on the reflector.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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2003

Ted,

Thanks for your prompt reply. can you be more specific in regards of the type of lighting, there are many fluorescent type lights; day light, white light, etc.

Thank you,

Enrique Segovia
job shop plater - Monterrey, N.L., México

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The referenced paper is 30 years old, and that topic isn't addressed. I don't know if they even had fluorescent coatings to produce various spectrums back then; but if they did, the meanings might have changed in 30 years anyway. I would suggest that you try to get the paper from AESF or a specialty library, for its many pages of proven lighting ideas, rather than focusing solely on fluorescent bulb spectrum, which may not be a significant factor anyway. Safranek tried, and ruled out, a bunch of things like polarization and laser lighting, and hard as it may be to find this literature, it's easier than trying it all and having to rule it all out yourself.

If you ever find yourself in the New Jersey area, please stop in and feel free to use our library. We can't make photocopies of this copyrighted booklet for you, but we will be pleased to look the other way :-)

Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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Ted,

Thank you very much for your help.

I'll try to find the paper you mentioned.

Enrique

Enrique Segovia
- Monterrey, Mexico
2003

Me also searching for the same lights behaviour against inspection if you find any solution, please let me know

Sarath Babu
- Chennai,Tamil Nadu, India
February 26, 2010

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Ed. note: At the date of your writing, Amazon had a copy of the Safranek book we've been talking about, Sarath. Follow the link and good luck.