Chrome Plating question

Most of our plating is O D on large rings ... but recently a job was set up
for I D.
The O D rings are about 20" and we have 12 anodes in the tank. Plating is
done at 1900 amps
The I D rings are the same size but we only use one 3" anode in the center
of the rings
The supervisor claims they did this job before and never had a problem
getting 1900 amps but the most I can get is 1100 amps at 20 volts
I believe it's my lack of surface area but he says " We never had a problem
before "
I checked the unit with an OD dummy load and have no problem getting 3000
amps so I know the units capable of supplying the current
Tom
Reply to
invntrr
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Check to ensure that connections are tight and clean. A few thousanths of a ohm of resistance in a connection or bussbar would cost you several volts at the current levels you're working with.
I'll say up front that I have zero experience with chrome plating, but I see a big difference between 12 anodes and one anode. More anode area will present less resistance (and heating) in the tank.
Scaling things to my experience at the 1-amp level with nickel, copper and zinc, I'm quite sure that an .003" dia anode would not work well. I'd bet you're right that you need a lot more anode surface area than a 3" dia anode of given length provides.
Reply to
Don Foreman
Sounds like thats all the surface area of the anode can handle. But then I dont know dick about plating.
Gunner
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Reply to
Gunner
I have 18.5 volts between the anode and ring ... a 1.5 volt drop from source at 1100 amps that is about what I would expect. We use 4.0"x0.5" bus
Ya ... I agree
It's a 3.0" anode It's another alien abduction story ... the supervisor really believes he did the job this way but something had to have changed. Ohm's Law has yet to be broken .
Tom
Reply to
invntrr
288-432 ASF @ 6-12 Volts and 130 degrees F. Plating at the higher voltage might be causing so much gassing at the anode, your not able to pass the current required.
Ed Angell
Reply to
Ed Angell
Remember that there is a current range needed for best plating per square inch of plating areal. If you are plating less area then you don't need as much current. You also need to have the necessary area of electrodes in the bath to get that current in addition.
-- Why isn't there an Ozone Hole at the NORTH Pole?
Reply to
Bob May
Thanks guy .... We have done chrome plating for over 50 years with probably 3 to 4 million units shipped.
The problem I'm having has everything to do with total area ... however , this old timer is telling me this particular job was done before with no problems ... I say bullshit !... something has changed since the last time they did it. I have 18.5 VDC at the work and can only draw 1100 amps.
It's a straight DC calculation using Ohms Law ... always has been and always will be. My surface area is too small to draw the proper current ...but I can't get that through the guys head
Reply to
invntrr
Try a hollow anode of the same size...
Reply to
Kevin Beitz
Ed - What's the title of your platers handbook? I've been looking for one and would like to hear any opinions.
Hul
Ed Angell wrote: :
: 288-432 ASF @ 6-12 Volts and 130 degrees F. Plating at the higher voltage : might be causing so much gassing at the anode, your not able to pass the : current required. : : Ed Angell : :
Reply to
Hul Tytus
Hul, I tried to send this to you direct and it got rejected. The handbook is a 1960 edition of the Los Angeles chapter "Platers Handbook" sponsored by the American Electroplaters Society. It's pretty basic and not a bad piece of information.
Ed Angell
Reply to
Ed Angell
Ed, thanks for the info.
Sorry about the rejection - the mail reader is a new one.
Ed Angell wrote: : Hul, I tried to send this to you direct and it got rejected. The handbook : is a 1960 edition of the Los Angeles chapter "Platers Handbook" sponsored by : the American Electroplaters Society. It's pretty basic and not a bad piece : of information. : : Ed Angell :
Reply to
Hul Tytus
On Wed, 01 Dec 2004 21:06:36 GMT, "invntrr" vaguely proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email
Which he did not know, and you asked for help. Bit sarky!
Reply to
Old Nick
I'm just a lowly tech and know little about plating ... when I say " WE " I mean the company .
The supervisor is giving me a lot of crap on an I D job and based on my calculations using Ohms Law he will never get 2000 amps ... something must have changed since the last time they did the job 2-3 years ago Specific Gravity of bath... surface area ... something but I can't figure it out , that's why I asked for advice.
I can get 3000+ amps on an O D job so the rectifier is working good.
Tom
Reply to
invntrr

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