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Can you safely zinc-plate a weldment that includes a hinge?

March 30, 2009

Our company's main product uses a zinc-plated mild steel welded enclosure, with a door at the front connected to the main body by an unplated mild steel hinge. The hinge is welded to both the door and the main enclosure for security reasons, as the enclosure often contains large amounts of cash.

We would like to weld the hinge and front door on before plating, to avoid having to weld and re-plate afterwards. One of our manufacturers tells us that it's no problem to plate over the hinge, and they prefer to do so. The other manufacturer tells us that it's problematic to plate over the hinge, and they don't want to do it.

Now, we like our first manufacturer's answer better (as long as it's correct), but the problem is convincing the second manufacturer. Is there any special technique required for zinc-plating over hinges?

Murray Love
mechanical engineer - Victoria, BC, Canada

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Hi, Murray. It's not a go/no-go question, it's a quality question. Just plating the inside corners of box-shape components is difficult to do well; plating a box and it's door and the hinge will be trouble. There will be no or virtually no plating in the recessed areas of the hinge. It's not impossible, but I think the plating will likely be poor quality.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 30, 2009