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topic 32574

Misc. problems in CED (cathodic electrodeposition) coating


A discussion started in 2004 but continuing through 2019

2004

This thread covers many general CED problems, but
PINHOLES have been moved to Topic 57561, "Pin holes in CED e-coating"

Q. I am getting the problem of half-coating and no-coating in CED. Defect rate is low. I have checked the contact points and there seems no problem with that. Defect rate might be around 1 in 100.

Madhukesh Jamadagni
painting shop - Mysore, Karnataka, India


2004

A. Check CED bath parameters. Check for bath and anolyte conductivity.

Manish Dhyani
- New Delhi


2006

Q. Please send me the information of the defects of CED COATING, and provide the answers for the questions relating to the topic. I will be grateful to you.
THANKS,

MANMOHAN SINGH
- Faridabad, Haryana, India


"Electrocoating: a Guidebook for Finishers"
by Electrocoat Association
from Abe Books
or
Amazon

"Handbook of Electropainting Technology"
by W. Machu
from Abe Books
or
Amazon

A. Hi cousin Manmohan. If you are having a specific problem or problems, please try to detail your situation. We have numerous Q&A's about CED in this forum and I am confident that someone here can help you. Regarding the general issue of possible defects and solutions, at least two full books have been written on electrocoating, and we can suggest that you try to get access to one or both of these =>

Luck and Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey
We need "Aloha" now more than ever



Dissolution of CED Coating

April 11, 2014

Q. Hello, could anybody help me understanding the reason for dissolution after CED coating on wheels? It mainly happens with small wheels.
Regards,

ale luso
wheels - Bologna, italy


April 2014

A. Hi Ale. Sorry, but I don't understand what you mean by dissolution after CED coating. Where, when, and under what conditions is this happening? Can you offer a synonym or expand upon your situation, please. Thanks.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey
We need "Aloha" now more than ever


April 15, 2014

Q. Hello, I'm sorry, pictures were missing. We produce steel rims and it happens that a few rims (1 to 10% depending on the reference) leave the CED coating bath only half coated; more precisely only the first half on the rim is coated.

32574-1 32574-2 32574-3

I've attached an explicative picture. Which parameters could cause it in your opinion?
Kind regards,

ale luso [returning]
- Bologna, italy


May 12, 2014

A. Sir,
It might be helpful to
- increase bath & anolyte conductivity,
- change the loading position.

Thanks
Surya

Sp singh
- Faridabad,india



Not getting e-coating despite proper voltage

September 25, 2014

Q. WE ARE GETTING NO COATING ON THE COMPONENT (LOAD BAR). WE GETTING THE PROPER VOLTAGE BETWEEN BOTH POLES AS PER SETTING BUT THE CURRENT IS GOING ONLY 15-20 A DC. OTHER HAND IF WE WILL PROCESS ONLY 2 OR 3 PARTS, WE ARE GETTING COATING AT THE COMPONENT. LET ME KNOW THE ACTUAL PROBLEM AND ALSO IF IT CAN BE THE PROBLEM OF RECTIFIER.

OMPRAKASH YADAV
- NOIDA,UTTER PRADESH, INDIA


September 30, 2014

A. Hi,

I'm assuming that that you are using a cataphoretic resin. If it is anaphoretic then the advice still stands but swap the words "anode" and "cathode",

Your problem maybe caused by the anodes restricting the current flow. So, when you put large areas of work in the bath the cathode current density is too low to initiate deposition of resin. Suggest:

1) Increase the number of anodes
2) If you are using anode boxes make sure that that they are filled with electrolyte of the recommended conductivity.

harry_parkes
Harry Parkes
- Birmingham, UK


October 26, 2014

A. Increase anode area
Increase voltage
Increase solid in bath
Increase bath temperature
That is it.
Regards,

Dr Halim Polat
- istanbul Turkey


November 17, 2014

A. Reasons for poor CED coating:

1. Poor electrical contact to the job to be coated.
2. Low cathode-anode ratio. This will be considered in plant design itself. But this may vary if the anode gets corroded; in case of CED, check the anode condition.
3. If ramp up voltage is too high, some parts may get poor coating.

Since amps is showing very low, it means the rectifier to be checked.

Selvakumar.S, chennai
- chennai, Tamilnadu, India



Finish coat cracked due to inferior E-coat under it?

January 21, 2015

Q. Working with a shop on a repair that used an aftermarket bumper cover (non steel) and when the finish coat was applied it cracked all over as it started to cure.

32574-4 32574-4t

Shop says it's inferior E-coat used by the aftermarket supplier. Your thoughts?

Phil W [last name deleted for privacy by Editor]
insurance claims - Houston, Texas, USA


January 2015

A. Hi Phil. I would not expect a body shop to be a coatings science laboratory, fully instrumented, and able to analyze precisely why an aftermarket bumper cover was unpaintable. But I would certainly trust a body shop -- people who paint cars day in & day out -- to be able to reliably paint proper substrates, and to 'fess up if they made a mistake. Thanks for the photo, but it will surprise me if anyone is able to look at it and contradict the body shop's assertion that the bumper guard is defective (although yes, after significant testing, a coatings science laboratory might well be able to).

opinion!Why does the body shop feel it's your problem unless you told them to use aftermarket parts? If you did tell them to do so, it's on you to prove that the parts were paintable and the shop screwed it up.

All costs associated with the quality issues of inferior aftermarket parts should be 110% the responsibility of the insurance company if they specified them. Neither body shops nor insurance companies should be allowed to substitute parts which are inferior to OEM parts, and initial problems like this are just the tip of the iceberg of long-term problems the insured consumer is stuck with. Consumer Reports has written repeatedly about this problem of manifestly inferior replacement parts being specified by insurance companies, but apparently with the government not watching them, that's what they do. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey
We need "Aloha" now more than ever



Water and paint flow marks

February 17, 2015

Q. We are getting water spots and water or paint flow marks on the components after curing. We could identify the marks if we blow air after UF and before curing. How to eliminate these marks?

RAJAGOPALAN SESHADRI
CED COATING UNIT - Hosur, Tamilnadu, India



CED Painting Defect: 'Partial Coagulation'

August 1, 2015

Q. Please tell me about the CED painting defect of "partial coagulation" on child bicycle parts like swing arm, center stand and prop stand.

prince Kumar
- gurgaon, haryana, India



Anodic to cathodic cell ratio in CED electrocoating

December 16, 2015

Q. Hi sir I want to know how much ratio in anodic and cathodic cell in CED bath

Sandeep kalidas raut
CED coating - Mumbai,Maharashtra, India


March 16, 2016

Q. How to calculate the anode cell ratio in CED? Please, I am preparing for an interview and I need a clear answer.

bala subramanian M
private automobile company - chennai, tamil nadu, india



CED Bath: Why/How has Sodium Increased with no other changes?

March 31, 2016

Q. Hello sir,
There is increase in the sodium content in the CED bath while all parameters of the bath are as per specification. Please suggest.

kalyani Argade
- Pune, Maharashtra India


simultaneous April 13, 2016

A. Na content increases due to carryover of alkaline cleaners from P.T. line. Rinse parts thoroughly.
Have you added any tubular part recently in your production?
If so, check the carry over.

Avinash Vidhate
- Nasik, Maharashtra, India


April 12, 2016

A. An increase in the sodium level can be due to drag out from your alkaline cleaner. Are you using a sodium hydroxide based cleaner?

Dan Mack
- Horicon, Wisconsin USA


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