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Brass V-blocks Overheating During Chrome Plating
Quickstart:
Alligator clips are generally not used when doing production plating. Rather, the workpieces are hung on plating racks which, in turn, are hung on a copper or brass bar which spans the width of the plating tank plus a few inches, and this 'work bar' sets in V-shaped 'saddles' mounted on the rim of the tank and bussed to the rectifier.
Q. Sir, we have a hard chrome plating plant. We have a product named 'plunger/Piston'. We are using current density of 35-40 Amp/sq.dm, having a 20 minute process time. Overall current passing is 4500 Amps for 20 minutes through Brass V-blocks. The problem is, we are often facing V block heat up in spite of using cooling water through it. Can we know what temperature water should be for v-block cooling?
Sanjeev Kumar- Gujarat,India
August 7, 2025
A. Hi Sanjeev.
There is nothing wrong with the water cooling idea -- it's even used on the continuous casting molds for steel manufacturing at very high temperatures, and I don't think the water cooling temperature matters a lot as long as the flow is sufficient.
However, firstly you may be able to reduce the current a bit without bad effects on your plating, at the cost of a few minutes more of plating time.
Secondly, I suppose it's possible that you have drilled so much for water cooling channels that the v-blocks don't have enough meat left on them.
Thirdly, are you bussing from both sides of the tank?
Fourthly, how's the temperature of the bus bar feeding the v-blocks?
If you can send a pic and a description of these v-blocks to mooney@finishing.com for posting here, it may be possible to quickly surmise the cause of the overheating.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted can be retained for immediate
answers or long term project help
A. Hi Sanjeev.
As I found on some site on the web, electrical conductivity of brass is only fourth of pure copper. Try to change your brass V-blocks to copper. And check your busbars also.
Good luck
Plating Engineer - Lod, Israel
September 21, 2025
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