Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
-----
Introduction to electrocoating, CED, ED, electropainting.
Q&A's, Problems & Solutions
Quickstart:
Electrocoating is a painting method where components are dipped into a tank containing a paint-like material (a paint 'precursor') which becomes actual paint only when electricity is applied to it, forming a thin layer of paint on the article.
The layer of paint which forms on the article is an electrical insulator; this 'steers' the electricity away from coated areas to uncoated areas. The advantages of the method are very good & level coverage even on complicated shapes, and very thin coatings of paint not achievable by other methods. Electrocoating can be decorative and used as a final finish, but it is more often used as a primer.
'Electropainting', 'CED', and electrophoretic' are synonyms. "CED" means cathodic electrodeposition, i.e., that the articles are negatively charged rather than positively charged for the coating process.
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Tip: Readers often just skip abstract questions;
they want to learn from your actual situation.
Q. HI,
WHAT IS PROCESS OF ELECTROCOATING ON 22 KT GOLD -RED MATTE FINISH?
- delhi, new delhi, India
October 3, 2014
? Hi Ankit.
Is it, the gold or the electrocoating that is to be red? Or are you saying there is no gold, just electrocoating that is of a color close to gold but more reddish? Please take several sentences and explain your situation. Thanks :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Is there any way to check if all parts are grounded on the rack? One of my biggest failures at paint line is parts not getting painted due to them not being grounded.
Thanks
- london, ontario, canada
December 18, 2014
Q. Good afternoon.
The company I work for makes lights for towers.
The Aluminium grade is LM6.
We want to move to E-plating^e-coating and then powder coat over it to reduce costs.
Will the powder coat "stick" to the E-plating^e-coating as good or better than traditional methods?
Lighting - South Africa
January 26, 2015
A. Hi Anton. I assume you mean electrocoating with an organic material, not electroplating? What finish are you presently offering that is more expensive than electrocoating plus powder coating? With proper pretreatment, and electrocoating followed by powder coating, you should not have adhesion issues and you should have excellent corrosion resistance.
However, Mooney's Law says that "Cost reduction programs always fail because they are grounded in the hubris that the product quality is good enough or too good, and it never is" :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Good morning Ted.
Thank you for your response.
You are correct, it is electrocoating.
At present we are using a Chromate conversion and then powder coating over it.
We clean the Al with non caustic cleaner, rinse, 5% Nitric acid, rinse, then Chromate conversion, rinse.
So the process of preparation is sufficient. But the Chromate conversion is a bit costly.
Everything
Lighting - South Africa
A. Hi again. Chromate conversion coating is the correct/best pretreatment for aluminum, whether it is to be electrocoated, powder coated, both in sequence, or whatever. Be very careful about claims that other treatments are its equal, as there is often a bit of sleight-of-hand there ...
For example, I've read some reports concluding that non-chromate pretreatments were just as good as non-chromates -- but what they glossed over was that chromate based primers were used after the pretreatment. Another report concluded that chromate based primers were no better than non-chromate, but glossed over the fact that the pretreatments all included chromate :-)
I think people misread things, sometimes deliberately, when they say non-chromate is as good as chromate -- my conclusion would have been "chromate is not needed in both the pretreatment and the primer, just in one or the other" :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I want to adhere a TPU Cover material to a vehicle interior part that is e-coated aluminum. What are typical surface tension values for e-coats in mN/m?
David Forrester- Grand Blanc, Michigan, USA
February 3, 2015
Q. I am a technical service engineer in India's leading car manufacturing company and I am facing the pH increasing of Reverse osmosis stage 1 and 2, and all the rinses including CED bath's pH is being found under specification. So can someone explain to me why the pH of RO1 and 2 is found always high?
Chandan Singh- Gurgaon, Haryana, India
May 3, 2015
Q. Hello, my question has to do with the maximum operating temperature for parts/products that are E-coated. What are the factors in the E-coating process that dictates the maximum temperature?
Mike Li- st. charles Illinois
April 22, 2015
A. Mike,
The operative question would be e-coated with what? E-coating ("coat" the verb) is a method, it does not describe a single type of coating ("coat" the noun). If there is a performance question, consult the manufacturer of the specific coating product you are using.
Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois
|
Q. I want to increase cycle time from 5 to 7 min. in unloading process in CED Plant. How can I do it? Nitin Vashisht- Udaipur,Rajasthan, India March 21, 2016 ? Hi Nitin. Sorry, I don't understand the question. Are you maybe implying that you have a programmed hoist serving a CED treatment line, and you wonder if it's possible for the time-motion diagram to be rearranged to allow more time on the unloading stand with the same production rate? Please try your best to spend more time and more words on your question than you want anyone to spend on your behalf in an answer, and then I'm pretty sure that someone will be able to help. Good luck. Regards, Ted Mooney, P.E. RET Striving to live Aloha finishing.com - Pine Beach, New Jersey |
"Q: What is more expensive? E-Coat or Powder Coat?"
A. Powder Coating is a lot pricier than E-Coating in response to the OP from above. Powder isn't always thicker than E-Coat. The MIL thickness can be adjusted by simply adjusting the voltage for the E-Coat bath. Less volts = "thin coat" More volts = "Thick coat"
- Atlanta, Georgia, United States
April 8, 2016
Thanks Roy.
Yes, there is an exception to every rule. But reliable e-coatings can be applied at much lower thicknesses (0.2 mils) than the thinnest reliable powder coatings (because powder has to melt and fuse and there are limits to the thinness to which it can melt and do that); and powder coating can be done much thicker than e-coating (nylon and other thermoplastic powder coatings can be applied via fluidized bed that are 10 mils or so thick and which supply electrical resistances of tens of thousands of volts, far beyond any E-coat rectifier's capacity). So I still maintain that an advantage of e-coating is thinness, and an advantage of powder coating is thickness, even though we may be able to cite some degree of overlap in certain cases :-)
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Is it possible to e-coat carbon steel with an additive that will exhibit static dissipative or static conductive properties? That is my equipment I want to resist static charge buildup and am wondering if there is an ecoat that can accomplish this versus a more expensive powder coating with carbon additives thank you
John Taylor- Chicago, Illinois
May 3, 2016
Q. Dear Sir ,
For an e coating of 20 microns on CRC, what are the in house tests that we can do to check the quality of the e-coating?
One I know is salt spray of 480 hours; other than salt spray what are the other test that we can do in house?
Regards,
- New Delhi / India
May 4, 2016
Q. I work as a wet painter. I was informed a little about our e-coat process. I have the basics about it. It's electrolyzed with positive and negative. My question is if it's electrified and you happen to put your hand in the such and such gallon tank, can you die from being shocked?
RANDALL BOESEN- Mayville Wisconsin
June 18, 2016
Q. We are powder coating job processors for Auto Industry at Pune India.
We are putting in a plant of CED. We wish to find out whether we can use a conveyorised oven for powder coating & CED at same time?
Both colours are black. In a row on conveyor one item may be PC & next may be of CED
Is it possible?
Please comment.
Thanks,
- Pune. Maharastra. India
June 22, 2016
Q. Hi,
I'm Umesh From Pune, India, looking as a Plant Head here... Would like to know about:
1. Can the CED give its effect of resistance to corrosion on Hardened Material?
2. And what if we do not remove any scale before coating and take directly in to 12 tank process?
finishing solutions - Pune, Maharashtra, India
July 13, 2016
Hi Umesh.
1. I'm not aware of any reason that CED can't be applied to hardened steel.
2. I don't think anyone can predict whether an unspecified "12 tank process" will be able to remove unspecified "scale", but I think we can say that it's unlikely to be a really suitable process for the purpose. It's probably better to prevent the scale with an inert atmosphere, or oxygen excluding wrapping, or to blast the scale off. Just one opinion.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi Ted,
Thanks for replying quickly and appreciate the same.
So, ED coat on hardened material will remain unresolved...
finishing solutions - Pune, Maharashtra, India
July 14, 2016
Hi again Umesh. Hopefully it will "remain unresolved" only temporarily. This is a public forum, not a consultancy, and we hope you will soon be back with some answers for us on that subject :-)
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I am studying e-coat thickness on aluminum base. What is the relationship between base size and e-coat thickness? How to calculate by formula.
How to calculate the relationship of ED coating thickness by the no. of parts loaded in ED bath or in 1 hanger. Thank you.
Dors Zaide- Manila, Philippines
September 14, 2016
A. Your e-coat paint should have an electrical efficiency rating of x amps per square foot per minute per micron. Your paint supplier should be able to supply you with the rating.
Dan Mack- Horicon, Wisconsin USA
Q. Hi Guys, I would like to use E-Coating for "Paint coating", Chemical milled or acid etched; name plates, metal labels: we have purchased a small E-Coat bath and I would like some more information to assist me on this journey. Can anyone assist me with further detailed info or send me to a reliable source?
Kind Regards
Peter
- Adelaide, S.A. Australia
September 24, 2016
Q. Is there any food grade coating available by this method?
mahesh parabVarie Valves pvt ltd - Mumbai, Maharashtra , India
September 29, 2016
Q. I have a question regarding E-coating life on welding joints... Also have concerns if any impurities because of welding to any component may lead to the ED life ... How can we improve SST life on welding joint?
Umesh Deshpande- Pune, Maharashtra, India
October 7, 2016
? Sorry, Umesh, I don't understand your question and would probably only add to the confusion by any attempt to answer. Please describe with several paragraphs exactly what steps you are actually doing. Thanks.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I am using a spring that has been electroplated. We are experiencing a high failure rate due to hydrogen embrittlement. The spring is used in an outdoor environment and needs rust protection. If I e-coat instead of plating, will this prevent hydrogen embrittlement?
Steve Head- Mesa, Arizona, USA
October 27, 2016
A. Hi Steve. I doubt that e-coating alone will provide sufficient corrosion resistance for outdoor use. Hydrogen embrittlement can be caused by cathodic electrocleaning, or the acids required in the pretreatment, as well as the plating steps. Are the springs baked for embrittlement relief immediately after plating? Are we talking leaf springs used in earth-moving equipment or little coil springs like in ballpoint pens -- because appropriate solutions will depend on the size and the environment. Thanks.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. The springs are 28 mm OD 61 mm long and 4.5 mm thick, made from 1055 steel, hardened to 50-55Rc then stress relieved. Plating has been black zinc. I don't believe they have been baked after plating. Our failure rate is about 7%.
Steve Head [returning]MFG Direct - Mesa, Arizona, USA
A. Hi again. The plating shop definitely should be baking these parts for hydrogen embrittlement relief as soon as practical after plating (preferably immediately, and certainly within a couple of hours).
Make sure you are dealing with a plating shop who knows their way around such issues because, unfortunately, the black chromate cannot be baked, which complicates the process and makes it: plate, bake, re-activate, chromate, dry. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. We tried Ed coating for one powder metallurgy( sintered) part which is having porosity by process nature.This process suitable for this type part. After coating we found red patch mark on part surface.The following process sequence we tried.
Cleaning-Rinsing-Phosphating-Rinsing-Ed coating-Rinsing-Air cleaning- Baking.
Sintered - Tamilnadu, India
November 3, 2016
! Trying to tell someone that e coating will not properly coat the inside of a box frame. He believes it will because the solution can get inside. From what I have read it's not going to work properly except near the ends. Look in comments of www.youtube.com/watch?v=EDVCV0ekjKQ
Tony Eggel- Ferndale California usa
November 25, 2016
Hi Tony. Even though the deposition is insulative and thereby tends to steer electricity to the uncoated areas, I think you're probably right that there will be little if any deposition in the middle of a box frame. This analysis by the Auto/Steel Partnership says as much, but notes that drilling holes can help .
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
E-coat finish and ground straps
Q. I am intending to mount communications equipment on a steel plate coated with e-coat and will need to attach a ground strap to the plate. Does e-coat produce a resistive surface. Can anyone provide me with a conductivity characteristics please.
Andrew McKeeCablex Pty Ltd - Bentleigh East, Victoria, Australia
March 17, 2017
A. Hi Andrew. Although I don't have the quantitative data you want, I can tell you two things to put the situation in perspective:
First, the e-coat finish is essentially paint, not metal, so it's going to be resistive. Second, something that gives the process an advantage over other ways to apply paint is that the coatings are consistent in thickness everywhere, and the reason is that, as the ions deposit on an area and are converted to insulative paint, the current stops flowing to that area. In short, it is not going to be a satisfactory finish for a ground strap attachment.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
E-coat Adhesion Concern
Q. Hi There,
What a wonderful site You've got here! I'm new on the finishing industry and in regards of e-coat, On the line where I run E-coat, I usually produce several customer's products during the same day under the same parameters, still, there is one customer that is often reporting a "Chip" condition after He does some riveting on the e-coated part, what gets my attention is that this is the only customer We're having problems with even when the others do similar processes after our paint.
The part has a zinc phosphate pretreatment done on the steel roll prior to the stamping process from my customer, and We think probably that is causing the adhesion failure, as the problem comes and goes on different lots.
We have done the quench testing on the part prior e-coat and part meets the spec, We have done the tape adhesion and the ethanol rubbing test and part meets the spec after e-coat.
We certainly don't know what else to do on the part to prove customer that paint is not an issue, any suggestions will be appreciated.
Plating Shop Employee - Mexico
May 31, 2017
Can't find electrophoretic lacquering services
-- this entry appended to this thread by editor in lieu of spawning a duplicative threadRFQ: Hello, Ted Mooney posted that there was a coating called electrophoretic lacquering, I tried to look it up and all I got was companies across the seas. Is there anyone here in the US that handles this and the process it takes? I work for a small welding/fabrication shop and I was thinking of trying this if it was not too costly to start up.
Thank you for your response.
North Idaho Ironworks - Spokane, Washington, USA
April 6, 2018
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?)
A. Hi Jeffrey. We added your question to a thread which should help clarify the situation. "Electrophoretic lacquering" has numerous synonyms, which is probably what is making it hard for you to find suppliers. It also goes by the names e-painting, e-coating, electropainting, electrocoating, and electrophoretic coating. In the old days, the work was usually anodic but the great majority of it today is done with the work being cathodic, leading to yet another name -- and possibly the most common -- CED coating (cathodic electro-deposition).
Most of the time electrocoating is done as a primer coating (all automobile and truck bodies are electrocoated to my knowledge). When it is done as a final decorative coating rather than as a primer, I and others sometimes call it "electrophoretic lacquering" to sort of imply that in this application we want it to be decorative. If you use the list of synonyms you will find dozens of threads on that topic on this site, and if you google for the synonyms you can probably find suppliers. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Looking to replace a 1964 Pontiac Steering Center. They offer e-coat, then a more expensive option for NON e-coating ... Seems like e-coating would be superior (thus more expensive) to no coating at all. Why would non e-coating be more expensive?
Pat Wood- Dallas, Texas, USA
April 18, 2018
Q. Does black e-paint on a stainless steel 3XX piece outgas? I want to apply to a piece that is next to optics.
Kostas Zafiriou- Somerville, Massachusetts USA
June 12, 2018
Q. We are using Electrophoretic Lacquer on brass chains, we need to increase the life of plating up to 6 months. Please suggest any method to increase the resistance to human perspiration.
Mayank SaraswatImitation jewellery Electroplating - Agra, Uttar Pradesh, India
February 20, 2020
A. Hi Mayank. It's a tall order to suggest what you should do starting with no information except that you're e-coating and not getting enough life. One approach is to polyurethane the chains after the electrophoretic lacquer. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
E-coating solvent: butyl glycol?
Q. Hey;
Can we use the Butyl glycol As Solvent for E-coating polyurethane lacquer?
Thanks in advance.
- Cairo, egypt
March 3, 2020
Q. Book or notes for PT CED - zero level to high level?
Dear sir ,
I have only 2 months experience and i really want to learn a lot about PT CED.
But sir as you know very well that support not available for freshers .
So i am requesting you please suggest me that how can I learn about this by myself.
Thank you sir, I hope you will definitely help me .
- Jaipur Rajasthan
February 2, 2021
A. Hi Jaipur. I believe that by "PT CED" you mean "Pretreatment" & "Cathodic Electrodeposition".
Pretreatment: any time you are applying any paint or organic coating you must first pretreat the surfaces to be coated. The pretreatment consists of cleaning, often followed by an acid dip, often followed by some form of phosphatization or phosphate coating. The pretreatment can be as simple as three stages (viz., a combined cleaning and iron phosphate, followed by two rinses, the last of which may contain a chromate or other chemical post treatment) or as complicated as seven to nine stages (separate cleaning, rinsing, acid dip, rinsing, possible grain refinement pretreatment, zinc phosphate, and several rinses, again the last of which may contain a chemical post treatment). These processes are not usually formulated from raw commodity chemicals by the user, but are usually purchased as a system from specialized suppliers.
Cathodic Electrodeposition: You will often see synonyms for this including e-coating, electrocoating, electropainting, electrophoretic lacquering, etc. I do not have deep knowledge of electrocoating, but I believe that when the technology was first introduced the approach was for the workpiece to be anodic, and thus AED or "Anodic Electrodeposition" was the predominant technology. I believe that almost all electrodeposition these days is done with the workpiece cathodic, thus CED. Sometimes electrocoating is the final finish as in "electrophoretic lacquering", and sometimes it is just a primer as is used on all automobiles frames/chassis these days.
sometimes on
AbeBooks or Amazon
(affil links)
free pdf is currently available from academia.edu
An excellent starting point for your study is "The Metal Finishing Guidebook" which is on-line for free and lightly covers virtually every finishing technology. After that you can google using the keywords mentioned here.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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