Sep. 02, 2024
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Q. What would be a correct choice for voltage whilst selecting a Decorative Chrome plating Rectifier?
At many job shops Chrome burning is a regular feature, despite other parameters being in control. I doubt if this is on account of using a higher voltage rectifier such as 16 or 24 Volt, when in actual use the required Voltage will be only 4-6 Volts.
Does burning occur if a higher Voltage is used to obtain the required amperage? Is using an 8 or 12 Volt Rectifier a better choice for obtaining higher amperage at a lower voltage or vice versa?
Thanks in advance.
Khozem Vahaanwala
Saify Ind
Bengaluru, Karnataka, India
A. Hi Khozem. As you know, Ohm's Law demands that voltage and current are directly proportional; so, for a fixed resistance, you can't raise or lower the current or voltage without proportionately raising or lowering the other. So the only way to vary the required voltage is by varying the anode to cathode distance.
But a rectifier should never be grossly oversized because it leads to extreme ripple, inefficiency and other problems. So, if you know that you never need more than 12 volts, get a 12 volt rectifier, not a 16 or 24 volt one.
The same things that cause burning in other plating solutions cause burning in chrome . . . the difference is that the operating window for chrome plating is very small because burning will occur at too high a voltage/amperage whereas no plating at all will occur at low voltage/amperage (say, less than 100 Amps/ft2).
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I will carry Ted's reply one further step. If you currently never exceed 6.0 volts, buy a 6 volt supply. If you occasionally get any higher, buy a 9 volt unit. If you use a 3 phase unit rather than a single phase unit, you will virtually eliminate ripple without a choke or huge capacitors. Ripple is extremely bad for chrome.
James Watts
- Navarre, Florida
Q. In India the general rule is to use only 3 phase Rectifiers on account of incoming line voltage problems hence I'm reasonably certain that ripple is not a major concern. However people tend to use higher Voltage rectifiers on account of versatility .
I wish to add a sequel to my above question :
When general parameters are normal, then what should be the correct distance of the component from the anode at say 150 amps /ft2 to avoid burning without compromising coverage?
Khozem Vahaanwala
Saify Ind
Bengaluru, Karnataka, India
A. I have seen anodes as far away from the cathodes as about 15" to 18" when plating bumpers or plating shafting vertically, but the rule in any plating is to get the anodes as close as practical, and 1-1/2 to 2 inches is common in hard chrome plating--so I don't think that there is a distance that is too close for decorative chrome plating as long as you can assure that they never touch.
But chrome has horrendously poor throwing power / covering power; so if one area of the part is significantly recessed you may need greater anode to cathode distance so that the relative distances from the closest and furthest anode to cathode distance don't vary excessively. For example, if the part has a 2" deep recess, it probably won't work for the nearer points of the part to be 2" from the anodes and the recess to be 4" from the anodes (twice as far away). In that case you might need to go to, say, 10" nominal anode to cathode spacing, so the ratio of closest to furthest anode to cathode is 10" vs. 12" instead of 2" vs. 4".
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Multiple threads merged: please forgive chronology errors :-)
Q. I am looking to purchase a rectifier for the purpose of chrome plating, I have discovered that there are different methods of control, but I don't know the pro's and con's of each. Could somebody please explain the differences between variable transformer, tap switch, and SCR control? Also, I assume I'll need up to Amps output to handle auto bumpers, if this is incorrect please let me know. Thank you.
Brian C
- Surrey, BC Canada
Ed. note: Since this forum has enjoyed a legacy of real names, and the camaraderie & warm aloha that allows. Without that connection, you're not into its spirit, and 'regulars' may be less likely to engage with you.
A. Hi Brian. The required amperage will depend on how many bumpers you plate at a time and how big they are. You should figure that you will probably not be able to chrome plate at all at less than 150 ASF, and 200-250 ASF is pretty typical, so 250 ASF is probably not excessive as a rectifier sizing specification.
SCR control means 'silicon controlled rectifier' control and is a solid state control method, a modern style, and probably the least expensive and simplest of the automatic control methods. The incoming waveform is 'chopped' to control the outgoing current. However, this means that when the rectifier is operated at substantially below its rated current, the incoming sine waves are chopped into 'shark fin' shape, with the result that there can be substantial ripple (AC component) in the outgoing current, which can interfere with proper plating.
Variable transformer rectifiers achieve control by varying the number of turns in the primary vs. secondary coil, so they are better at achieving reduced ripple at low output. However, they are not solid state, but use a motor to adjust the transformer, so they have moving parts. They are probably more expensive and less reliable than SCRs.
Tap switch rectifiers are manual. As the name implies, there are taps in each of the three windings, and you manually turn a handle attached to brushes to vary the primary to secondary voltage. Nothing wrong with them as long as you don't need automatic control. Good luck.
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
on AbeBooks (rarely)or eBay (rarely) or(rarely)
A. Ripple is normally controlled by chokes or capacitors. Both are effective for a given percentage of the load that they are designed for. They all work fine at that point or at 100% output which is hard on the unit.
Solutions, buy a three phase unit. It will be a full wave unit, so you will be using 6 "phases" which have a significant overlap making ripple of no consequence unless you try running a amp unit at 50 amps.
The true state of the art is a supply that runs at mega HZ or giga HZ and uses a true chopper, not the one that Ted mentioned. These are tiny units vs a normal power supply. They generate very little heat, so are more efficient at all power settings. The electronics portion is a sealed unit with heat sinks so none of the lousy atmosphere gets to the critical components. Draw back-- They cost more. I am not sure how big they are now. 5 years ago, they were only available in the 300 amp area, but that has been steadily going up.
James Watts
- Navarre, Florida
James is right that the state of the art is to use solid-state "chopper" circuits to generate high frequency rather that operating at 50/60 Hz because this greatly reduces the size of the components. In the plating industry, this technology is called "switchmode" rectifiers.
Regards,
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
(You're unlikely to find this for sale ... but copies are in select libraries
byfrom AbeBooks * rarely available *or eBay * rarely available *or* rarely available *
Q. Can I do hard chromium electroplating with a A / 6 V rectifier ?
NAOUI KADOUR
SARL SODEC - Algeria
A. Yes, Naoui
Although 12 volts is more typical for rack plating, if you have anodes very close to the part (maybe an inch or two), it is possible to plate with 6 volts. In fact, Clarence Peger suggests only 4.2-4.7 volts with his reversible rack plating system. Of course, Amps will only plate parts up to perhaps 2 square foot in surface area (which counts both sides).
For general rack style plating, however, Robert Guffie says 9 volts minimum, 12 volts suggested. Please explain your situation in more detail. Thanks.
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Sir,
In chrome plating rectifier how much ripple is allowed? in 250 kw rectifier how much ripple will generate in 10,000 Amps current rating. Transformer primary wave is pure sine wave form.
Natarajan.G
Maintenance incharge - B'lore, Karnataka, India
A. Hi Natarajan. The ripple will depend on a number of things including what percentage of the rectifier's capacity you are using and what rectification technology is used, G., but the mathematical ripple in rectifying a 3-phase sine wave to DC is 5 percent. You can read a lot of detail about this, and a number of opinions in thread/topic .
One of the readers in the referenced thread offers his opinion that the shape of the disturbance is as important or more important than the actual amount of ripple. Further, opinions differ on how much ripple is allowable. But for the briefest answer, it is usually said that ripple should be held to 5 percent or less for chrome plating. Good luck.
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
RFQ: Looking for chrome rectifier min 5k 3 phase/220 north Jersey
Andrew M
[surname deleted for privacy by Editor]
broker - Newark, New Jersey, USA
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
Q. I'm currently hard chrome plating with a amp, 6 volt, water cooled, tap switch rectifier. I have trouble getting past amps max. My busing, cabling, fixturing, etc. all seem to properly sized and there is less than 4 inches between my anodes and cathodes (parts). My parts are small diameter (1/4 to 5/8"), long length (4' to 12' long) and I suspect that they are a source of significant resistance. So, I think I need higher voltage to overcome the resistance. Two other plating shops I've spoken to say they do hard chrome plating with 12 volt rectifiers. Does anyone else out there use a 6 volt rectifier for hard chrome? If not, what voltage do you recommend?
Peter Krasucki
Plating shop - Webster, New York, USA
A. Hi Peter,
6V rectifier may not be enough to support A working current, unless resistance is very small. For your case, better to switch to a higher voltage capacity rectifier or lower down working ampere by reducing total plating area.
Regards,
David
David Shiu
- Singapore
A. Hi Peter,
I think you don't need a amp rectifier to plate a 5/8" dia X 12' long job. You have an oversized rectifier. 6 volts is enough for a 4" gap, however for hard chrome application you need at least 8-12 V rectifier capacity if you plate at 1" or more anode/cathode gap just in case you get a job where area to be plated is more. Your job will not require more than amps, so if you are able to give it that much current and still stay below 6 volts you don't need to change your rectifier. If this is a production job try conforming anode(3/4" gap)- you might just plate it at 4.5-5 volts and not require more than 800- amps... you save a lot on the electricity plus the part resistance will not trouble you much. Other plater as you say might be using 12 volts rectifier as they might be plating at say 6" gap or having jobs with more surface area..ALL THE BEST
Vikram Dogra
Irusha India - Chandigarh, India
Q. Vikram - I forgot to mention that I'm plating 5 to 10 parts per load. So the total surface area for 5 bars at 1/2" x 12' is square inches. At 3 amps per square inch I would need amps. With the rectifier turned all the way up I only get about amps.
Peter Krasucki
- Webster, New York, USA
A. 3 options: Decrease the anode to cathode spacing or use a more conductive solution or use a larger power supply.
Temperature adjustment might help, but I do not like the lower temp for hard chrome as it adversely affects the distribution.
The quickest and cheapest thing is to try decreasing the spacing by 1 inch and see what happens.
James Watts
- Navarre, Florida
A. Peter in that case you would def need a 12 V rectifier ORRRR...take my idea go for a conforming anode. 1/2 inch spacing would be too much to ask for for a 12' long anode so try a 5/8" or 3/4" spacing , you might just be able to plate it at 6 V with desired results.. (I mean faster plating rate / energy saving and above all cost towards a new rectifier.. go for it..)
Vikram Dogra
Irusha India - Chandigarh, India
A. 1. 6V is too small for hard chromium plating.
2. The solution plays an important role in the conductivity of this process. A properly operating solution should have a conductivity of 450-500 mS/m. Metallic impurities decrease rapidly the conductivity which means that you need more V for the same Amp.
3. Try to reduce Cr3 and iron.
4. If you are not able to get rid of the impurities then the remedy is increasing the CrO3 concentration.
Sara Michaeli
-Aviv-Yafo, Israel
Q. How to calculate the rectifier capacity in terms of amps?
How related to our job to be coated?
Abdul nazar
- coimbatore, India
A. Hi Abdul. I'm not sure if I understand your question, but you simply multiply the surface area of your job in square feet by the required current density in amps/sq.ft. (or the surface area of your job in square decimeters multiplied by the required current density in amps/sq.dm.). The current density requirement might vary depending on the workpieces you are processing and the method, but 200-250 Amps/sq.ft, 20 Amps/square decimeter is probably enough for decorative chrome plating, but hard chrome plating should probably be done at about twice that.
If you can explain the details of your situation, I think we can help you further. Good luck.
Regards,
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi I have a triple chrome plating kit from a hobby plating company and I need help with volt and amps.
I have a power supply that has a gauge for volts and goes up to 25 volts and a gauge for amps that goes to 50 amps and a dial that is for adjustment. Now, say I need 2 amps to plate my part, do I just adjust the knob till I get 2 amps on the amp gauge and don't worry about what the voltage is, or must I worry about the voltage also.
Tom Barbush
- Harrisburg Pennsylvania usa
A. Hi Tom. Voltage and amperage are locked together by Ohm's Law: V = A x R, so there is actually no way to vary them independently anyway.
The plating solution will have a resistance that you can't change except by moving the parts closer to or further from the anodes. So if you choose the amperage, you have to let the rectifier produce however many volts it needs to get there. Chrome will not plate at all until about 1 Amp per square inch, so 50 Amps would do a part of up to about a maximum of 25 square inches surface area (counting both sides). If you are doing some kind of "imitation chrome" however, it isn't actually chrome, and probably plates at about 1/4 to 1/3 that much current. Good luck.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hello and good day to everyone here around. I am a newbie and I would like to do a small experiment about chrome plating at home but I don't have enough knowledge about what basic and right equipment to purchase and use.
I am hoping that someone could help me around here regarding the basic equipment. I am planning to chrome plate about a size of a body of an electric guitar. I think it's about 20 inches in height and 14 inches in width with a 2 inches thickness . Definitely, the container of the item would be a bit bigger than the item that I am going to plate. With that size, I would like to ask what kind of rectifier I'm gonna need to buy? How many amperes? How much volts do I need to use to plate it properly? And lastly would that be all the equipment needed?
I hope I can get an answer regarding these matter. Thank you so much for taking the time reading my letter.
Benjamin Lucero jr.
- Manila, Philippines
A. Hi Benjamin. If the part is 628 square inches, you'll need a minimum of 750 Amp rectifier ( to Amps would be better) at probably 9 volts minimum. But a lot more equipment is required: please see our "Introduction to Chrome Plating". You should surely start with small scrap parts rather than with something large or important though! You will nickel-chrome plate dozens of parts before obtaining marginal success.
A scalpel and needle & thread is not the heart of surgery, a skilled surgeon is ... similarly, some people feel that they are still relatively new to chrome plating after years at it and thousands of parts successfully plated. Good luck, but please start smaller! -- and I'd suggest getting a few months experience with some other plating before trying to deal with toxic, carcinogenic, hexavalent chrome plating solution. Good luck!
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Please I need your advice. I want to start decorative chrome plating on a smaller scale. Because of the power source, which is going to be a petrol generator of about 7 kva, I want to go for a single phase rectifier. What is the type of single phase rectifier I will need that will reduce the ripple that is common with single phase rectifier in order to have good chrome plating? The input voltage range between 220 to 240 volts. I will prefer rectifier with variable voltage and current. The output will be direct current.
Thanks for your assistance.
Abbey
Abiodun Jide
- Lagos, Nigeria
A. Hi Abbey,
Hexavalent chromium plating needs a very smooth (low ripple) DC supply. Ideally I would start with a 3 phase generator. The rectified DC output is suitably smooth for chrome plating without additional smoothing.
The ripple from a single phase power supply has a very high
ripple and needs a great deal of smoothing before it can be
used for hex Cr. Traditionally the smoothing circuitry
consists of inductors (chokes) and large value capacitors. For low current supplies, say up to 10 amps this is fairly easy. But when when we start to consider hundreds of amps the whole thing becomes heavy and expensive.
If single phase must be used I would look at switch mode power supplies and compare costings. They have smooth DC and can have variable voltage control. In fact I would consider switch mode for 3-phase as well.
I had a quick look for switch mode on Google. I found the following link helpful:
http://www.dynapower.com/products-switchmode.php
I'm not sure Ted will allow a commercial link. I'm certainly not trying to promote them! We have small SM units all around us for in computers, cell phones etc. but it is useful to see industrial size supplies.
Does this help? Have I missed to point of your question?
Harry
Harry Parkes
- Birmingham, UK
Thanks Harry.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I am an interested researcher in the field of composite coatings such as Ni-TiO2 and Cr-Al2O3 prepared by electrodeposition. I want to buy a rectifier for this purpose. In most articles only the amount of applied current density has been reported and there is not any information about working voltage. Is equipment with maximum current 20 A and maximum voltage 12 V proper for composite electroplating?
Please guide me to select proper rectifier for electroplating.
Ali Jam
- Isfahan, Iran
A. Hi cousin Ali. When you plate one metal with another you consume perhaps .2 to 2.0 volts for the actual reduction operation (depending on the half-voltages of the plated metal compared to the substrate). You might consume another small amount, probably not over 1 V, as resistance in the bussing system. The biggest voltage drop is due to the resistance of the plating solution, and is proportional to the anode-to-cathode spacing. As you will know, amperage and voltage are related by Ohm's Law of A = V / R
Practically, this means that if you want to control the amperage -- which you do -- you don't get to choose the voltage: it's just whatever voltage is required to deliver the desired amperage. Practically speaking a 12 V rectifier will be adequate for most plating operations except where you are processing large parts which demand a big anode-to-cathode spacing and therefore have a high solution resistance ... and with a 20 A rectifier you won't be doing big parts. I think you'll be fine.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Thanks for your reply.
Based on your answer 12 A and 12 V is enough for electrodeposition of composite coatings on small parts, e.g., with less than 20 cm2 surface area. Again it is emphasized that the goal is co-deposition of composite coatings including a metallic matrix and ceramic particles as reinforcement. For example in Ni-TiO2 coating in addition of reduction of existing Ni2+ ions in the bath, TiO2 particles (added in the bath) also should incorporate in the coating.
In this condition, is it enough 12 V or not?
Yours Sincerely
Ali Jam
Ali Jam
- Isfahan, Iran
A. Hi again, Ali. Co-deposition of this sort involves occlusion. The particles are not electrically attracted to the cathode; rather, if they are in the vicinity of the cathode as the nickel or chromium is reduced onto the cathode, they become entrapped in the deposit.
This is not meant to imply that composite coating is as easy as pie -- it's quite difficult; some companies have been in business for decades by licensing their knowledge and technology. But as far as I know, the particles do not add enough resistance to the passage of current through the solution as to require higher voltage rectifiers. Good luck.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi all,
I have to select 20,000 amps 12 V rectifier for hard chrome plating. Which one will be good IGBT modular technology or SCR?
Thanks
Ramesh
Ramesh Yadav
- Brisbane, Queensland, Australia
Q. My situation: Hi I am looking to buy electroplating rectifiers of - amperes for copper and have been given a choice of both IGBT rectifiers and Diode rectifiers.
I can't make up my mind as to which one will be the best and what advantages one have over the other. Kindly shed some light on the above please.
Thanks and Regards,
Arihant Agarwal
If you are looking for more details, kindly visit electroplating rectifier for sale.
- Delhi/India
A. Hi Arihant. While I spent a lot of time on the road visiting & servicing plating shops over the years, and would have been willing to express my opinion on such subjects in the old days, I have been largely away from plant visits for a while and don't have much actual experience with switchmode and IGBT rectifiers in use; and there is obviously not a lot of very long term reliability history yet.
opinion! But my belief is that in principle they are superior technology to diodes, just as transistors are superior to vacuum tubes, and LEDs are superior to incandescents for most lighting applications.
Transformers operating at high frequency rather than 50-60 Hz line current has made engineering sense ever since they were popularized by the personal computer business back in the late 's. You probably need to speak with some users of IGBT and determine whether with regard to large IGBT power supplies we are still in the early days, similar to the early days of transistor and LED unreliability; but my guess is that we are not.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Thanks a lot Ted. Will highly appreciate if others can shed some more light on the above.
Arihant Agarwal
[returning]
- Delhi, India
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Ed. note: They are very welcome to as long as brand names & suppliers aren't discussed (why?).
Q. I have two hard chrome plate rectifiers, both are (+) Amps and linked with tank. If I have small job work I use Amps if I get big job I join them together like Amps. At present my Output voltage 18V, if I use 24V is there any reflection on my job, and what is the result will come up if I use more than this?
Razack Syed
Industry - Chennai, Tamilnadu
A. Hi,
12 voltage is enough for rectifier. To have more amperage you will destroy the rectifier, because a rectifier should be working at the high amperage that it's built for.
I have seen many connections from the rectifier to the chrome bath which are wrong connections. With wrong connection the rectifier loses so much of the power (amperage) through the cable. The + and -cable to the solution should be twisted from rectifier to the chrome tank.
Regards,
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
Ed. note: With regard to combining multiple rectifiers, readers might like to review topic a, "Clubbing / coupling / connecting multiple rectifiers to one plating tank"
Q. How long to run rectifier after putting in new anodes in chrome plating?
Casey Cashwell
- Spartanburg, South Carolina
Q. I have an offer from a rectifier company for Dual rectifier that could work separately like two rectifiers to two different tanks with separate control for voltage and current. I want to know the disadvantages of dual rectifiers, and should I have single output rectifiers instead or not?
Aly ismail
electroplating factory - Egypt
Hi Aly. I have not seen such dual rectifiers for production plating myself, although I have seen small bench-top power supplies with dual outputs, and it has been commonplace for decades to build electronic power supplies which offer both 5V and 12V from one core.
So I can't personally recommend either using them or avoiding them, but I assume the situation is very much like any other case where two devices are combined into one: you save money & space at the cost of a certain loss of flexibility and reliability. If you anticipate no production changes that would require changing either of the two output capacities, and it saves money, it sounds like a reasonable approach.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Current drop from rectifier during hard chrome plating. What causes related to rectifier because rectifier gives alarm current drop. We have IGBT rectifiers.
Sudhakar chavan
pace auto parts - pune Maharashtra India
A. Hi sudhakar. I would agree with you that this is probably not a process problem (assuming the parts are racked firmly enough that there is no chance of contact break) but a rectifier problem. Unfortunately, it's probably very difficult to guess exactly where in the rectifier circuit the defect is occurring.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Dear Sir,
What does the standard say about the maximum voltage to be used if we are looking at 100 A/sq.ft. of current flow.
We are seeking a Amps Rectifier, however; not certain on what should be the voltage we need?
Note: We are into copper plating on mild steel. Plating bath is acidic in nature. The anode to cathode distance is 5 inch.
Tirath Nagda
- Vadodar, India
A. Hi Tirath. A complete analysis of voltage losses is a bit complex, but the solution resistance is the lion's share of it. Solution resistance can be measured as described in papers such as
http://www.ejournal.unam.mx/rmf/no495/RMF.pdf
or if you look hard on scholar.google.com or surfacequery.com, you may find published charts of the solution resistance of typical plating solutions (Charles Faust published a great chart for ASM International which I unfortunately lost to Superstorm Sandy).
But there is an old saying popularized by players of the card game "Bridge": A peak is worth a thousand finesses. It means, of course, that basing a strategy on theory & statistics should be forgone if you have actual knowledge which trumps it :-)
You've been operating this copper plating line for years now according to the long dialog in topic , so you already have a great deal of info as a starting point -- what have been your typical voltage vs. amperage readings?
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Dear all,
Good Day!!
I am new to electroplating world, I need to calculate the power consumption, efficiency and all relevant information regarding Amp 6 VDC Rectifiers, about its working and designing.
I will be grateful if any of you can provide me the check sheets for predictive maintenance of Rectifiers. Also if anyone of you could proved me the link of book.
Thank you.
Regards,
Waqas Badar
- Karachi, Pakistan
Q. Hello,
I'm considering doing some copper, nickel, and chrome plating on die cast. The type of parts are vintage car parts ... like trim and dash components.
My question is very general to start with:
1- Can I be able to use 220-240 single phase power?
If it's better for three phase can I use a rotary phase converter to supply power to the rectifier?
2- How many input amps do I need to a rectifier ?
3- Can you with this very limited information suggest the size and type of rectifier ?
thanks, Jaan
Jaan Ojala
- Bend, Oregon usa
A. Hi Jann.
&#; Yes you can use single-phase rectifiers for small parts.
&#; Decorative chrome plating will require an absolute minimum of 1 Amp per square inch of surface area, but 2 Amps per square inch is probably more realistic. You can take that amperage, multiply by 9 volts and get the output Watts required. Assume the rectifier is about 60% efficient and you'll have the input Watts required ... from which you can figure the input Amps.
&#; Rectifiers of that amperage and 9 volts should be okay. Copper and nickel plating needs about 1/4 Amp per square inch; but it may not be realistic to plan on using the same rectifier for nickel as for chrome, not only because of sizing but because the nickel plating may go passive while you are setting up for chrome.
We are always very happy to try to answer any & all questions that we can. But people of all experience ranges visit these pages: from grammar schoolers for their science projects to post-doctoral researchers wanting confirmation of highly obtuse theories by people with decades of plating research experience; from people who have been supervising $6 million copper-nickel-chrome plating installations for 30 years to people who have not yet attempted to plate a dime with copper or a penny with zinc, yet want to take on the replating of heirlooms :-)
What we try hard to do is not to accidentally lead people down the garden path spending lots of money and generating wastes which are very expensive to dispose of, with little hope of success. Have you read our "Intro to Chrome Plating" so we're on the same wavelength? Do you realize that replating of vintage diecast auto parts will start with filling of the inevitable pits, a job demanding considerable acquired skill? Do you realize that you can't do chrome plating in a basement or garage, only a plant designed for this toxic, carcinogenic, material?
You may well be more than capable of doing copper-nickel-chrome plating of vintage diecastings, you may well know a lot more about it than me -- but I don't know you, you haven't told us your experience, and we don't want our answers to impel anyone towards buying expensive plating equipment if they're not ready.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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Q. Hi,
I am a jewelry student and to make a little extra money have been making copper chain (i.e., bracelets, anklets, and keychains). The clasp I would like to use for my bracelets is not copper and I would like to be able to electroplate them, but do not have access to a rectifier. If anyone could give me instructions on how to turn a battery charger &#;this on eBay or Amazon [affil links] into a working rectifier or even to build one from scratch it would be much appreciated. (I have worked with electronics before and feel comfortable soldering)
Thank you!
Adam Mendel
student - Atlanta, Georgia, USA
On the other hand, copper electroplating for non critical applications can be very forgiving of ripple in the DC power supply, as long as the voltage never goes negative. (In that case you would be experimenting at the cutting edge of electroplating technology - pulse reverse plating *L*.) Have you tried plating with the battery charger as-is ? You may get acceptable results without any modifications. As with any plating process, you will need to adjust current to prevent too high a current density which will give poor appearance or burning. With a non adjustable power supply like a battery charger (or you can even use a car battery if the charger gives too much ripple) you adjust the current by setting the distance between the part and the anode. Further apart means less current, slower plating, and generally a more uniform result.
If you intend to sell anything you electroplate, better look into EPA 40CFR 433 because electroplating was the nation's first categorically regulated industry; and while the EPA is unlikely to find and hassle a hobbyist, if a neighbor complains you'd be in trouble if you are selling electroplating services or electroplated items.
A. There's more to plating and to rectifiers than most people think, Adam, but for you to to turn a battery charger into a fixed voltage rectifier you should connect it to a 6-volt battery to dampen out the ripple.
Multiple threads merged: please forgive chronology errors :-)
Q. I am interested in setting up a home copperforming bath. To avoid the cost of a rectifier, can I use a 6-volt 1.25 amp or 6-volt .75 amp motorcycle battery charger? I have also seen inexpensive car battery chargers [battery charger &#;this on
eBay or
Amazon [affil links]
] that have multiple settings (6/4/2 amps). I am just trying to keep my costs down and I would like to avoid the expense of a rectifier.
Thanks,
Daniela Pal
student/hobbyist - Phoenix, Arizona, USA
A. Six volts is high for copper plating and extremely high for electroforming, so I do not think that you will have much luck with taking the low budget way out. With extreme agitation, it might work.
James Watts
- Navarre, Florida
on AbeBooks or Amazon
A. Yes you can use it. Plating rectifiers are much better but expensive. You can even work with short connected chemical battery (that is original 19th century method). Some very good old books (Pfanhauser, Langbein, Gore, Urqhardt, Watt) on electroforming can be downloaded (free) from internet archive website.
According to R. von Neumann's book on jewelry making and design/electroforming chapter/ .
you must add variable rheostat (22 Ohm is ok) and ammeter/but you can work without it (ammeter!) -- just somewhat more complicated way. Copper sheet can be used as anode. Hope it helps (little bit more) and good luck!
Goran Budija
- Cerovski vrh Croatia
A. You can use a battery, but you need to control the current applied to the workpiece (cathode). You will need a rheostat and an ammeter to control and measure the current. Although electroforming sounds very easy, in reality it is quite difficult; you will probably get good results when you first start, but as you use the copper solution, the quality of the deposit will deteriorate because you will not be controlling the electrolyte composition. I would recommend you look at the references given above and in other replies to similar questions on this site and find out how to measure and control the bath composition. You may want to set up a simple chemical analysis facility to ensure your solution is the correct composition.
It would also be a good idea if you had your battery on charge whilst you are doing your electroforming, then the battery will be acting as a power "stabiliser" and you will be more likely to get a constant current once you have set your rheostat to the required take-off current.
Remember that electroforming is not only about depositing metal, it also includes ensuring your mandrel/template is adequately pretreated to ensure you get good and consistent deposition.
Regarding the anode, copper sheet will be OK, but you should at least bag it to prevent any undissolved particles escaping into the electrolyte - if they do, you will get a rough deposit on your cathode.
You will also need to agitate either the workpiece or the electrolyte to make sure you get good solution movement.
Finally, you need to ensure you can dispose of your waste solutions. This includes both your cleaners and copper electrolyte. You MUST NOT tip them down the drain because they will be harmful to the environment and anyone who is unfortunate enough to come into contact with your waste stream. Such legal disposals can be quite expensive to arrange, but to do it illegally can (and should) result in much heavier fines and possible imprisonment (at least in the UK!).
Once you have got a good setup and complied with your local waste regulations, good luck with your electroforming and long may you have fun doing it.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
Q. I am building a new copper electroforming tank and want to make sure I get the correct rectifier/plating machine. I built an 8 gallon tank using a 10 amp precision control rectifier a while ago for jewelry and small sculptural objects and it has worked like a charm. I am now looking at taking my work to a larger scale. The new larger tank holds 45 gallons of electrolytic solution and 6 monster copper anodes. I assume that a tank of this scale will require a significantly larger electric load. Does anyone have any suggestions on what size rectifier I will need to be able to control the voltage and amperage on the low end that the electroforming process requires?
Michael Parrett
Artist - Saint Louis, Missouri, USA
byon AbeBooks or eBay or
A. Hi, Michael. The surface area of the parts that you will be plating determines the rectifier size. If you are planning to put 6 times as many parts in your 45-gallon tank as in your 8-gallon tanks, the required amperage will be 6 times as high. If you were actually drawing the full 10 amps previously, you will now be drawing 60 Amps (although that sounds high). The voltage will be essentially the same as before, and I imagine it was less than 6 volts. Good luck.
Regards,
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
To whom it may concern, I am interested in electroforming nature. I recently purchased a plating station - specifications are:
Power Supply 230 Vac
Amperage 2.2 A
Watt 500 Watt
Plating lines 2
Plating line parameters 0-12 Vdc / 0-10 Adc-7V
Heater 200 Watt / 230 Vac
Air pump 72 L/Hour
CRS 1
CRS speed (RPM) 2-4
Horizontal tank 3 (150 W x 70 D x 70 H mm)
Vertical tank 3 (95 W x 80 D x 205 mm)
Dimensions of station (mm) 315 W x 335 D x 280
It allows plating/forming of gold, rhodium, copper, nickel, silver, bismuth, and others.
My question is as follows:
How can I control the amps on my unit to do electroforming at 1/10 amp per sq inch? I saw a 'fine tuner' that plugged into the 'positive' anode of the rectifier, then you attached your anode into this unit; but could not afford to buy it from America as the shipping was $180 USD! Please tell me what this unit is called and where I can buy one. I am based in Greece.
Thanking you in advance.
Marianna Papageorge
Hobbyist - Mitilini, Lesvos, Greece
A. Hi, Marianna.
Please google "plating rheostat" -- I think this is what you are envisioning. Good luck.
Regards,
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I have a fairly basic question about the power supply we'll be using for electroforming. We have a 5V 200A DC powertec supply, and would like to know two things: 1] what's the best way to meter the amps, and 2] is it possible to adjust the amps on this particular supply. I know this is a little off the electroplating/forming track, but if you are able to shed any light on either question it'd be greatly appreciated.
I've pasted a few pictures of our unit below - as one of them shows, there is a "V adjust" dial - do you happen to know if adjusting the volts affect the amps as well? Or is there a device that connects to the molex 9-pin plug that allows you to meter and adjust the output?
Otherwise, if you have any suggestions you think we should consider, please feel free to let me know.
Gaelen Armstrong
- Fairfield, Iowa, USA
A. Hi Gaelen. If you have no instructions or schematic for this power supply it will be very hard to get it to do anything. We can see the connection posts for the 200 Amp output and two of the three 10 Amp outputs (the other one might be cropped off the left side of your top photo?) but we have no information at all about how those outputs are controlled -- just the assumption that if you connect something to the 9-pin and 6-pin molex connectors, something will happen. There might be pins for a voltmeter and an ammeter in each of the outputs, and additional pins for feedback of some sort but it's hard to guess.
But you cannot independently control voltage and amperage anyway. Ohm's Law tells us that the current will be V/R, or the voltage will be IR.
Regards,
Ted Mooney
, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi,
I'm looking to electroplate brass rings with gems glued on top of then (though I believe this is then electroforming as the copper builds on the glue and around the ring and gem?). What I'd like to know is:
What amp and volt size rectifier would be best? Some say 3 amp is enough for small scale Jewelry others insist on going up to 25 to 30amp. I can get a 3 amp 20 volt online for relatively cheap.
They have other smaller rectifiers, all have US plugs but do not state the plug voltage. I live in Australia and need to be sure I can use an adaptor (not a converter) to plug into a 220v outlet.
If I use brass rings do I need to paint then first with a copper conductive paint? What if I want to eventually do silver plating? Would brass be okay? I know I would need a different bath for that though just thinking of possibilities for the future.
Instead of using a copper conductive paint could I instead make my bath with copper sulphate, absorbing acid and distiled water mixed together? I have read that this works as a copper conductive paint when mixed with a watercolor medium but could I just use it as the bath instead?
Lastly, do I need to agitate the bath continually? I wouldn't mind a slightly organic look and have read that without agitation this will happen but I do not know to what extent.
Many thanks!
Rachel
Rachel Rose
- Southport, QLD, Australia
A. Hi Rachel,
The size of rectifier, in terms of current, depends on the area the work to be plated and the current density required. The current density is measured in amps per unit area. I know the in Oz, you have chosen the metric system so I'll use amps per square decimetre. Typical plating CDs are 1 - 4 amp/dm2. So you need work out the area to be plated and find the optimum CD of your plating process. Then workout the current that you need. As an example:
CD 2 amp/dm2
Area 3 dm2
Current 2 x 3 = 6 amps
Voltage is important too. You must be able to vary the voltage to set the current to the wanted value. Only a few volts will be required: a fixed voltage of 20 volts would be far, far too high.
It is vital for safety reasons to use the correct mains input to the power supply. Some small power supplies accept a wide range of voltage inputs but most do not. I am a little surprised that the input voltage is not marked on the unit.
The brass rings will not need a conductive paint but will be ready to be copper plated after cleaning. Likewise silver plating. One caution regarding silver. Thin coatings will migrate into copper or brass causing severe discolouration. You either need about 25 microns or a "barrier layer" of a suitable metal to prevent migration. There is a lot information on the subject on this site.
I don't know why you need a conductive paint and have no idea if the mixture you propose would work. Don't know what "absorbing acid" is. Should it read "ascorbic acid"?
It is usually desirable to have agitation. It is necessary to replace the metal plated at the cathode. Agitation greatly helps. If fresh metal is not brought to the surface we get a coarse, powdery deposit called "burning". I wouldn't call it a "slightly organic look"!
Is this of any help?
Harry
Harry Parkes
- Birmingham, UK
A. Hi Rachael
H hope you realise that almost all silver plating is done from a cyanide solution.
There are non-cyanide processes but they require close chemical control and may not be any less toxic.
You may not even be able to buy cyanides, but if you do, you will need an antidote kit, training to use it and never work alone.
Lots of other considerations; safe storage, disposal, local legislation etc.
Not trying to scare you but these are serious chemicals
Geoff Smith
Hampshire, England
Q. I have a BK precision model dc power supply; it has a meter range where you can choose 0-50 V and 0-25 Vand it looks like it's only a 2 amp system. I want to make a 3 gallon bath for copper plating, putting at least 6 pendants 3 inches by 3 inches down the bar.
When trying to calculate what I would need in a rectifier it came out to 50 amp system for a 36 sq inches of area to cover with the 3 gal. bath.
my question is this bk is not powerful enough for what I need is it? what size rectifier would I need to be able to plate several large pendants at one time?
Josette redwolf
- key largo, Florida
A. Hi Josette. Are you plating only one side of the pendants and, despite being about 3" x 3", their surface area is only actually 6 square inches each? (If there were 6 pendants of 2 sides at 3" x 3", that would be 108 square inches, rather than 36 square inches.)
Even still, a 2-amp power supply would give you 2.67 ASF which just might be barely enough. If the area is correctly 36 square inches, you could do 8 ASF, which should be more than enough. If the area is 72 square inches (if you forgot the back side in your calculation but will be plating it), you would be at 4 ASF and I think that should do it. I don't know how you calculated 50 Amps, but it wasn't right :-)
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi,
Can someone explain what to look for when buying a rectifier?
I will be using it strictly for electro plating copper.
Thanks
Scott Richard
- Tampa, Florida, US
A. Hi Scott. Copper plating rectifiers can range from very inexpensive hobbyist units to industrial ones costing tens of thousands of dollars each. What is probably most important for a hobbyist is that the size (voltage and amperage) is right and that it actually be designed for use as a plating rectifier.
Regarding the size, it depends on whether you will be doing electroforming or decorative electroplating. If electroforming, you probably will be using something like 2 Amps per square foot of surface area of your components; if you are doing decorative electroplating, probably 10X that current. For hobbyist electroplating it's hard to imagine a need for more than 6 volts. The rectifier should allow you to choose between voltage control and amperage control; that is, you should be able to choose any voltage you wish or to flip a switch and be able to choose any amperage you wish.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q
Ted,
Thanks for your quick response. This is only for plating, specifically barrel plating. That being said would the same rule of thumb (approx. 20 Amps per 1 sq. ft of surface area) from your post still apply? Or does barrel plating amperage differ from direct connection amperage?
Thanks
Scott Richard
- Tampa, Florida, US
Usually available on eBay ; sometimeson AbeBooks or Amazon free pdf is currently available from academia.edu
Hi Scott. Please detail your actual situation: Are you a production plating shop, or a hobbyist, or a captive machine shop venturing into plating, or other? Is the plating line already existing and you want to add a copper plating station to it? How big of a plating barrel are you planning to use? Do you know the load size (weight and/or surface area)? What copper plating process: cyanide, bright acid copper, copper pyrophosphate? Will you be using a proprietary plating process? (Usually the supply company offers a technical data sheet that tells you typical rack plating and barrel plating current density).
The short answer is that barrel plating generally employs much lower current density than rack plating, but higher voltages. The longer answer is that plating barrels can range from 2" dia x 4" long to almost 2' dia x 4' long, and Q & A forums like this can often answer very specific questions or refer you to books or articles for more general answers, but due to time & space constraints they usually cannot directly answer generalized questions without specific details. Thanks and good luck.
Regards,
Ted Mooney
, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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