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E-coating -- what is it?

Q. Anyone:

I am an estimator for a metal stamping operation in Illinois. Some of the cost I have to quote are those of plating. I understand there are several different types of finishes. I don't know what e-coating is. Can you please tell me about it, or refer to me a place/book where I can get more information about it?

Thanks,

Carlos Gdeleted
- Elk Grove Village, Illinois


 

A. Hi, Carlos.

E-coating is another name for electrocoating, electropainting, or electrophoretic lacquering. It is used to deposit a paint or lacquer coating (rather than metal, as is deposited by electroplating). It's more of an application method for paint or lacquer than a coating per se.

Parts are dipped into a vat of the lacquer or paint and are electrified in order to promote a reaction at the surface which deposits the paint. Depending on the chemistry, the workpiece can be anodic or cathodic, but these days it's usually cathodic, which has given the process still another common name "CED coating" (cathodic electrodeposition). It is used on very large parts, such as automobile bodies, to apply a primer coat that doesn't miss any spots, and it's also used on smaller parts such as lamps and jewelry to deposit a thin and durable lacquer (electrophoretic lacquer) as a decorative finish.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


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A. Yes, and no. E-coating is a process of using electricity to apply paint or lacquer, however, it is primarily used for smaller parts as a primer. I manage an e-coat facility that works parts from the size of a quarter to a rear axle on an 18 wheeler. E-coat is also a better choice over powder coat if thickness is a concern, the paint is distributed more evenly without fluctuation.

John Cdeleted
- Sterling Heights, Michigan


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Q. E-coating...is the paint a flammable or combustible?

P-coating...is the powder actually a plastic?

Chris Bdeleted
- Oxford, Michigan


February , 2006

A. E-coating is done with the parts immersed in a water-based solution. While you would need to get any relevant hazard information from the actual supplier, I've not heard of it being flammable or combustible and certainly wouldn't expect it to be.

Yes, powder coating is done with powders of thermosets or thermoplastics.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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Q. Which process is more expensive, E-Coat or Powder Coat?

Scott Ldeleted
- Evanston, Illinois


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A. That is a little difficult to answer, Scott, because there are different types of e-coats and powder coats, and some e-coats are intended only for use as a primer, and most powder coating requires some sort of pretreatment. But powder coating is generally far thicker than e-coating, involving the deposition of significantly more material, so it is probably reasonable to say that powder coating is more expensive. Perhaps a shop that offers both will confirm or refute this for me.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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Q. I want to know the process flow & the entire time for the process completion?. Time for each process & what happens after the completion of each process. I will be happy if you explain me with pictures.

Sandeep deleted
- Chennai, Tamilnadu & India


+++++++

A. Hello, Sandeep. This public forum is a good place to ask for a quick one-paragraph introduction to a technology you are unfamiliar with, and it's also a good place for answers to highly specific question. But as you get into wanting someone to prepare detailed sequences for processes, with pictures, theories, etc., your needs will probably have to be met by books on the subject. =>
But maybe one of the vendors of the process has a brochure that will help you. Good luck.

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

Handbook of Electropainting Technology


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Q. Can e-coating process be carried out on the outer surfaces of silencers. What are the characteristics of e-coating. Is it corrosion resistant?

Srikanth m.r
production supervisor - Bangalore, Karnataka, India


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A. Hi, Srikanth. Here in America, a "silencer" is a device fitted on the barrel of a pistol to reduce the noise, and yes they can be e-coated. But I think what you call a "silencer" is what we call a "muffler" -- a device to reduce exhaust noise on motorcycles and automobiles? As mentioned, the coating is thin but it is corrosion resistant. The biggest question I would immediately have would concern the operational and maximum temperature of the application. For high temperatures you usually need metals or ceramics rather than organic coatings. Good luck.

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

January 14, 2008

Q. Which one is better, e-coating or powder coating? Do they perform the same aside from powder coating being thicker? What are the advantages and disadvantages?

Leonardo Antonio
- Winnipeg, MB, Canada


January 14, 2008

A. Hi Leonardo. We've mentioned some general advantages of e-coating -- complete coverage and very thin coatings being the principal ones. But "better" is only meaningful in terms of compliance with a detailed list of desired properties. If you tell us exactly what application you have in mind, I think people will be able to list advantages/disadvantages for that situation/ circumstance, and help you make an informed choice between the two, or to use the two coatings sequentially, which is also often done.

Attempting to suggest which one is "better", independent of the application, rarely works ... it's like trying to suggest the advantages & disadvantages of travel by ship vs. travel by rail -- it is wasted effort and very misleading until we know whether the planned trip is from Los Angeles to Las Vegas, or Los Angeles to Hawaii.

Good luck.

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

February 14, 2008

Q. Hello everybody! What is the best method for treatment of a new replacement vehicle frame for a 59 Chevy. E-coating, powder coating - or a combination? What would You suggest? Thank You! Al

Alfons Wolff
- Haimhausen, Bavaria, Germany

February 14, 2008

A. Hello Alfons. Powder coating will not be able to cover all areas of the frame, whereas e-coating will -- and it is done by all OEMs. But both in sequence would actually be best. Good luck.

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

September 30, 2008

! Mine is not a question but a comment about powder coating. I run a small job shop specialty coating service and use a Gema gun. The commercial guns have KV's ranging from 10-100 with the normal application amp set at 45 for powder attraction. I use a batch method with carts to handle large parts and racks for small parts. I think the application thickness would depend on the application KV's applied to the part for powder attraction, don't you?
Say for instance a tank holding 50 lbs of powder using an air mix and low KV's, I think with air blowing the powder around the tank as the parts passed through would flock the powder very proportionally and with low KV's the thickness could be adjusted.
Permits for E-coat and chemicals are very costly and a start up operation could start around $ 500,000.00 so I am told by suppliers.

Jimmy Cherry
owner of coating shop - Washington, North Carolina



Hi Jimmy. Yes, there are clearly advantages to powder coating over e-coating, usually including lower capital cost as you mentioned, and also thicker coatings, the versatility to easily go from one color to another, and one type to another, apply multiple coats, etc.

But although you can vary the thickness of powder coating, no matter how thinly you apply it, you won't get it to melt and flow and cover at anything approaching the thinness and consistency of a e-coating with no missed spots in crimped areas, under spot welds, etc. 1 to 2 mils would be a common powder coating thickness whereas 2 tenths of a mil would be a common e-coating thickness.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

October 12, 2008

Q. What type of e-coating should I request so that I can spray epoxy primer over top of it with no adhesion or reaction problems?

Shawn G Lavene
- Dayton, Ohio


August 17, 2009

Q. I'm working on a stamping part for Caterpillar. They ask E-coating with 600 hours salt spray test.
Which kind of E-coating do I need to use?
Thanks!

Frank Wang
die & mold making - Shanghai, China


February 3, 2010

Q. My company currently powder coats the components of the bike racks it manufactures. These bike racks go on the back of vehicles. Is E-Coat a replacement for powder coating. Is it as durable as a powder coat finish for exterior applications.

What are the advantages and disadvantages of E-Coat vs. Powder Coat.

Thank you.

Richard Noddin
manufacturer - Alna, Maine


February 4, 2010

A. Hi, Richard. The vehicles you mention would be first e-coated, then powder coated or wet spray painted. Obviously, the vehicle manufacturers do not think of e-coating as a replacement technology, but as a supplementary technology.

If your bike racks have tight interior corners or a bit of weld splatter, etc., e-coating can get you complete coverage whereas powder will not. But powder is thicker and probably more corrosion resistant and attractive. I think the powder coating is more durable. To do it best, apply e-coat and powder coat in sequence.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

April 12, 2010

Q. We have been e-coating a small magnesium (AZ-91D) part in a black e-coat with minor issues (some occasional small chipping).

I am now proposing a larger part (AZ-91D front housing for a handheld computer with scanner) that would be e-coated in a metallic finish.

Are the metallic finishes as/more/less durable than the solid coats and is there a secondary process that improves durability without sacrificing wall consistency?

Bob Bruffey
- Norcross, Georgia


April 22, 2010

A. Hi, Bob. finishing.com just completed a major study of corrosion resistant coatings for zinc die-castings for the International Zinc Association, and we found the metallic colors about equal to the solid colors in corrosion resistance. Polyurethane top-coating does significantly improve the corrosion resistance, but it adds significant thickness.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

December 2, 2010

Q. Hi,
I have a product which is polyurethane E-coated.
It is clear and it will give good exterior resistance.
One thing I want to discuss: solid coats are more powerful than the metal coat because of their physical structure? Or the solid coat arranges in plate-like structure so it helps to inhibit the corrosion.

chandresh varsani
- Rajkot, Gujarat, India


A. Hi Chandresh. As mentioned immediately above, finishing.com's testing for IZA did not show evidence of your hypothesis leaning either way, although I can't rule them out since the amount of data we collected on that particular subset is scant.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

August 17, 2011

Q. Hi.
I want to know about the material used and process used in E coating, I want to do this coating on molds which are used to produce ABS plastic products which are injected at very high temperature about 150-200 °C, which would be better option for non sticky coating.
thanx in advance.

DEV SHARMA
- New Delhi India

August 17, 2011

A. Hi, Dev.

Sorry, I've never heard of using e-coating on molds. It's not that I claim to have heard of everything, just that I can't help.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

October 5, 2011

Q. I am considering a process where I e-coat a cast iron ring then mold rubber to the ID..
My question is if the e-coated ring is exposed to a 150 °C/300 second heat cycle (rubber molding cycle) will it damage the performance of the e-coat??
Thanks for your help in advance..

Dave Ford
- canton, Michigan

March 26, 2012

Q. Hi. I work for product development at Ford. We were asked to "glue" a stamped steel bracket to a piece of aluminum and then E-Coat it. I need to know what the highest temperatures these parts go through so I can find a suitable epoxy to use. Can you answer this question?

Thank you.

Mills, Tracey
- Dearborn, Michigan, USA


March 27, 2012

A. Hi Tracey.

To my limited knowledge the e-coat tank itself operates at about ambient temperature. But curing is usually required. The normal temperature for this is about 375° F, but there are low-temperature curing paints available that can be cured at 180 °F. It is also my understanding that there are UV curable e-coats.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

March 29, 2012

Thank you, that'll help tremendously!

Tracey Mills
- Dearborn, Michigan, USA


March 30, 2012

Q. I have a question in regards to e-coating and how it relates to automotive body repair and refinish of plastic parts. It's recently been suggested to me that if the e-coat on a plastic painted component (such as moldings, bumpers, finish panels, etc.) has been disrupted by collision damage or as a result of repairs, subsequent sanding, priming and refinish will be rendered null and void as the base coat will merely blister and peel as a result of the damage to the e-coat. This would essentially require part replacement. Can you provide thoughts on this?

Wayne Hunt
- Greensboro, North Carolina


March 30, 2012

A. Hi, Wayne.

That one is probably better directed to auto body shops, who will be much more familiar and knowledgeable than we are with what is required to effect a robust repair. But I do note that I've never heard of e-coating being applied to a plastic component because it is an electrolytic process that can only be performed on a conductive surface, so the story sounds fishy to me.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

April 24, 2012

Q. Hi, I am purchasing a bumper for my Jeep Wrangler and I see most manufacturers use powdercoating and a few use the e-coating? Can you tell me which would be more durable and which would be more resistant to rust? Thank you.

Jerry Megs
- Nassau, New York


April 25, 2012

A. Hi, Jerry.

Regrettably, a manufacturer's sales spiel almost never reveals anything important about the finish because it is not intended to educate you, but to induce you to buy :-(

I doubt that any bumper is only electrocoated, unless it is intended for repainting by the buyer, and the electrocoating is meant as only a primer. To the extent possible, please investigate customer satisfaction with the various brands and make your decision based on that.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

Bumper for Wrangler


August 13, 2012

Q. What factors affect the choice of an e-coating for gray iron pipe fittings?

morris_key
Morris Key
Chemical consulting - Van Alstyne, Texas, US



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October 24, 2012

Q. This question is related to aluminum die cast parts that are used on fencing, primarily the die cast components are decorative ( finials and post caps ) the biggest problem is the industry typically powder coats the parts, yet within the year we see several parts peeling and corroding. Clients are now requesting to have the parts e-coated and then powder coated. My question is will we see an improvement or is this just a problem due to adhesion.
Your help would be extremely helpful.

Regards

Henry Mercieca
- Richmond Hill, Ontario, Canada


October 24, 2012

A. Hi Henry. While every extra layer of coating has the potential to reduce corrosion, lack of e-coating is probably not the key issue.

opinion!   Although it's not possible to do a failure analysis based on such limited information, my bet is that the aluminum components used to be properly chromate conversion coated and no longer are. It is unfortunately very common these days to allow government regulators and wet-behind-the-ears environmental engineers in swivel chairs steer industry toward implementing well-intentioned but foolish & wasteful substitutes for time-proven finishes in the erroneous belief that we are "helping" the environment by saving an ounce of chromate ... while sending a ton of fabricated product to the junkyard.

Step 1 is to find out if the parts are still chromate conversion coated, and fix it if they're not.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

October 25, 2012

A. I suspect the chromate was too heavy, in which case the powder coat will peel off. Under powdercoat (or any organic finish) the chromate must be very thin, slightly iridescent, not bright gold.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

Editor's note:    
   Mr. Probert is the
   author of


January 30, 2013

Q. What pH should be maintained in the 7 tank process for rinse water?

What is ED process?
What should be recommended DFT of ED paint?

Praveen Khairnar
- Pune, Maharastra, India


February 2, 2013

A. Hi Praveen. In my opinion rinse tanks are for rinsing, they are not process tanks. Therefore, you should not add anything to them to control pH but should merely run an optimal amount of water through them, i.e., enough to guarantee quality without wasting water. Anything you add constitutes something that you are not rinsing off.

It is probably risky to take a 2-letter acronym like ED and try to insist on what it means, because it's a big world with a lot more than 676 things in it (26 x 26). But in this context it presumably means "electrodeposition" and additionally probably implies electrodeposition of paint rather than electrodeposition of metal (electroplating). Thus ED probably means the same thing as e-coating, electrocoating, electropainting, electrophoretic lacquering, etc.

Typical e-coating thicknesses are probably a few ten-thousandths of an inch. Good luck.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

March 24, 2013

Q. I have an ED coating plant for General Motor India. One metro train manufacturing wants to make ED coating and PT on aluminum cast parts. Is it possible to use steel ED coating line for aluminium cast parts? Or what do I need to put in additional in same line.

Pravin Chaudhary
Development manager - Baroda, Gujarat, India
  ^- Privately contact this inquirer -^


July 29, 2013

A. Yes, you can process Aluminium parts in the same line. You have to be careful with the degreasing and phosphating baths. They will require additional controls.

Gurvin Singh
Coatec India -

Mohali, Punjab, India



December 5, 2013

Q. I want to achieve C5-M corrosion protection as per ISO 12944-5 [link is to spec at TechStreet] which could last longer i.e. more than 20 years. How much coating thickness it should have with CED coating on mild steel? What are the tests should be specified?

Ashvin Ambaliya
- Pune, Maharashtra, India
  ^- Privately contact this inquirer -^


December 6, 2013

A. Hi Ashvin. Although it is possible to somewhat adjust the thickness of CED coatings, they are insulating, which inherently slows down the process at a rather low thickness (maybe 35 microns or so). I think CED coating is an ideal BASE for a 20-year coating system, but not an ideal topmost layer.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

September 12, 2014

Q. Hi. Great forum.

We import aluminum components from a source in China. Most have chrome/nickel plating, but some have a new e-coating. Can an e-coating be expected to have the same adhesion strength as the metal coatings? What are some possible causes of blistering/peeling of the e-coat?

Thank you.

Bob Kasberger
- Sheboygan Falls, Wisconsin


October 2014

A. Hi Bob. E-coating is paint, not metal. It does not have the adhesion, hardness, or scratch resistance of metal. Poor pretreatment is the cause of most adhesion issues, i.e., the aluminum was probably not properly cleaned and chromated before e-coating.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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