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 max for
rectifier
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

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.


On Wed, 01 Dec 2004 04:33:20 GMT, "invntrr"
wrote:

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 max for
rectifier
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

On Wed, 01 Dec 2004 04:33:20 GMT, "invntrr"
wrote:

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 max for
rectifier
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


Sounds like thats all the surface area of the anode can handle. But
then I dont know dick about plating.

Gunner


"I mean, when's the last time you heard of a college where the Young
Republicans staged a "Sit In" to close down the Humanities building?
On the flip side, how many sit in's were staged to close the ROTC building back in the '60's?
Liberals stage protests, do civil disobedience, etc.
Conservatives talk politely and try to work out a solution to problems
through discourse until they believe that talking won't work... they they go home and open the gun cabinets.
Pray things never get to the point where the conservatives decide that
"civil disobedience" is the next step, because that's a very short route to "voting from the rooftops"
Jeffrey Swartz, Misc.Survivalism

"Don Foreman" wrote in message
...
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 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

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.

Ya ... I agree

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.
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


On Wed, 01 Dec 2004 04:33:20 GMT, "invntrr"
wrote:

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 max for
rectifier
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

"invntrr" wrote in message
news:kQbrd.2815$M57.1849@trnddc01...
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 max for
rectifier
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

My platers handbook says the current density range for hard chrome is
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

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?

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 bull**** !... 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

"Bob May" wrote in message
...
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?

Try a hollow anode of the same size...

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:
:
My platers handbook says the current density range for hard chrome is
: 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
:
:

--
- for email, put the word "keep" in subject line -

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

"Hul Tytus" wrote in message
...
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:
:
My platers handbook says the current density range for hard chrome is
: 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
:
:

--
- for email, put the word "keep" in subject line -

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
:

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

Thanks guy .... We have done chrome plating for over 50 years with probably
3 to 4 million units shipped.

Which he did not know, and you asked for help. Bit sarky!

"Old Nick" wrote in message
...
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

Thanks guy .... We have done chrome plating for over 50 years with
probably
3 to 4 million units shipped.

Which he did not know, and you asked for help. Bit sarky!

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