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"Misc. problems in CED (cathodic electrodeposition) coating"



This thread covers many CED problems, but --

• Pinhole problems have been moved to Topic 57561

Current questions:

<= Ed. note: Please!
No abstract questions.
Huh?

September 6, 2021

What is the function of anode cell. Someone tell me.

Ajay Verma
Line supervisor - Faridabad, India
^


September 18, 2021

A. Dear Ajay Varma,
Greetings,

Its Functions are to act as an opposing electrode to the product being painted and to remove the acid continuously released by the paint during the deposition process.

Shivam Pandey
Process incharge - Fharidabad [India]
^



September 26, 2021

Q. My name is ashuyashu. I have a doubt in our CED process:
1) sheet metal comes problem patches issue
2) after phosphating part is dry and rust observed

These two problems lasting 6 months. Please help me.

Ashu yashu
Student - Karnataka
^




Previous Closely related historical postings, oldest first:

2004

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

(affil. link)





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

(affil. link)

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
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^



Dirt in Coating

2007

Q. We are facing dirt/impurities problem on parts after CED coating.

Kalidas Suryawanshi
- Pune, India
^


2007

? Hello, cousin Kalidas. if you can give us some info, I think our readers can help! Send some pictures, and tell us what you can. If you lack sufficient data, the paint vendor, system vendor, or an e-coating consultant may be able to help. Good luck!

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


2007

A. Dirt can come due to improper cleaning in the pre treatment line. It can be due to dirt in the E-coat tank. It could be due to dirt in the rinse tanks after E-coat. It could be due to dirt being blown around in the oven with the forced circulation. It could be because of one or more than one of the reasons above. And the reasons above could also be due to improper housekeeping or ingress of dirt and dust in your E-coat shop.

Test each and eliminate. I assure you this does not require NASA technology.

Gurvin Singh
Coatec India
supporting advertiser
Mohali, Punjab, India

coatec india
^


January 14, 2018

A. Check for sludge material in phosphate bath ... if it is high, then desludge it immediately. This will solve your problem.

baljeet_babli_singh
Baljeet Singh
- Ludhiana, punjab, India
^


August 31, 2021

A. Dear kalidas
Reason of dust..
1- not proper manual cleaning
2- kod/degreasing FAL pointage down
3- contaminated rinse
4- sludge increase in phosphate tank
5- contaminated DI water..

Shivam Pandey
Process incharge - Fharidabad Haryana
^


September 21, 2021

A. 1. Kindly install filter housing just before CED tank.
2. Use 10 micron filter in CED bath for 10 days and plan to use 10 micron bag filter once in three month.

3. Check CED bath circulation :- it should be properly work, causes of poor circulation paint settling started in bath then generate dust when settling burst.
4. Check incoming material quality first :- it should be dirt free , need & clean material required for ced.
5. Add Solvent as per spec. Less solvent also create dirt or improper finish.

Dhirender Pratap Singh
Senior Executive - Looking Paint Process - Haryana, India
^



Ra value of CED coating

May 20, 2009

Q. PLEASE TELL ME HOW TO CHECK THE Ra VALUE OF CED COATING.
WHAT IS THE RANGE FOR OEM VEHICLES?
WHAT ARE/IS THE INSTRUMENT USED FOR CHECKING RA VALUE?

KAPIL VASHIST
ENGINEER - INDIA
^


June 2, 2009

A. Ra is checked by roughness gauge.
Better you ask your paint supplier for Ra Parameters.

Thanks
SURYA

SURYAPAL _
- DELHI, INDIA
^


July 23, 2009

A. Hi,

Normally Ra value can be checked with use of Perthometer. try it.

Anand.

V. Anandaraj
- Chennai, India
^



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
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


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
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^



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
^


September 18, 2021

Dear sir
Greetings
Anode and cathode ratio-1:14

Thanks

Shivam Pandey
Process incharge - Faridabad [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 mani
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
^



June 27, 2016

Q. Hi
What is maximum oven temperature for CED jobs?
Can we put CED & Power Coated jobs into one batch for Curing the coatings?

Please give details.
Thanks & Regards

Vivek Nirgudkar
powder coating & CED coatings - Pune, Maharastra, India
^


July 7, 2016

A. Generally CED Paint cures at 150 °C / 20 minutes or 160 °C / 10 minutes Effective Metal Temperature. Oven Air temperature can be set depending on the Material thickness (Component) and time available for Oven curing.

If it is thin material may be 170 °C, 30-40 minutes more than sufficient to cure. In case of thick material like Forging or Casting we may go ahead up to 200 - 220 °C.

Logically we can bake both Powder and E.Coat in the same oven and there will be not any issue in the baking as long as if we meet the baking window criteria.

However E.Coating is a 'wet' process and it is cured in an oven to promote cross-linking. Solvent and Moisture evaporation takes place. Whereas in Powder, Curing causes the particles to melt and also serves as the catalyst for a chemical reaction that produces the desired finish. Both are different process.

During the Hot air circulation sometime loose powder particles deposits on the E.Coat surface before curing causes finish problem. Hence I would not advise Technically. Let us wait for some expert comment please.

Saravanan P.M
- Chennai, Tamilnadu, India
^


July 2016

thumbs up signHi. That sounded like "expert comment" to me. Thanks!

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^



March 24, 2017

Q. How can we control roughness after CED coating? It is varying a lot. I want to maintain it to its standard.

monu mittal
- gurgaon, haryana, india
^


June 14, 2017

A. CHECK EARTHING.

PRASHANT KUMAR
CEPL - PUNE,MAHARSHTRA,INDIA
^



Anode Cell Area Calculation

October 7, 2017

Q. Can anyone please help me how to calculate the Anode cell area/ no. of Anode cells required in ED Coating process according to Area of Component or Tank size?

Also how to select the range of Rectifier?

Arunprabhu A R
Designer - India
^


November 27, 2017

Q. Can anyone please help me how to calculate the Anode cell area/ no. of Anode cells required in ED Coating process according to Area of Component or Tank size? How do we know what is the capacity of anode in relation to surface area? How much surface area is covered by one anode?

We manufacture wheel rims; when we hang these on a basket after CED coating some area is unpainted where they are touching each other. What is the real cause of this

Rohit Kumar
- Faridabad haryana ,india
^



Masking for CED Coating

January 22, 2018

Q. Hi
We'd like to mask the wheel rim knurling during CED process.
Please suggest any masking.

Felix prasad
- Chennai, India
^


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