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Misc. problems/defects in CED (cathodic electrodeposition) coating


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Q. Hi sir,
I am having one small doubt regarding dot contamination (like popping). This only comes at body c-zone area, that means nearby the anode location.

Note: our dip coating system.

Suresh Nataraj
NEROLAC - Bangalore, Karnataka & India
April 11, 2018

Ed. note: Please forward a photo of the problem to mooney@finishing.com for posting here.





CED coating defects

Q. Please explain the defects of CED coating.

sathish kumar
employee - India
September 5, 2018


SUGGESTED E-COATING, CED, E-PAINTING BOOKS
for Shops, Specifiers, & Engineers


../abwd/ced3_electrocoats2020
"Electrocoat: Formulation & Technology" by Bruggemann & Rach (2020)
avail from eBay, AbeBooks, or Amazon

ced4_electrophoretic_deposition2017
"Electrophoretic Deposition (EPD)" by Nathan Bass (2017)
avail from eBay, AbeBooks, or Amazon

ced1_electrocoating2010
"Electrocoating: a Guidebook for Finishers" by Electrocoat Association (2010)
avail from AbeBooks, or Amazon

ced5_epainting1980
"Electropainting: A survey of principles and practice" by Reginald Leslie Yeates (1980)
avail from eBay, AbeBooks, or Amazon

ced2_electropainting1970
"Handbook of Electropainting Technology" by W. Machu (1978)
avail from eBay, AbeBooks, or Amazon
(as an Amazon Associate & eBay Partner, we earn from qualifying purchases)

A. Hi cousin Sathish. More words please -- are you asking a previous poster to clarify the defects they reported so that you can help them? If so, thanks.

If you are looking for help yourself, you can read this thread, as well as threads 23154, 38297, 51966, and 57561. You can search the site using the term "CED defect" for many more threads on the topic.

You can also hopefully get access to the books about CED coating which we suggest ⇨
I am not aware of training courses for this subject is India, but hopefully a reader local to you will advise (please tell us your city because some areas of India probably aren't easily accessible to you).

Best of luck!

Regards,

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


A. Dear Sathish, There are lots of defects in CED coating, as it's a very broad area.
But I will explain some defects which are usefully common for all CED Coating lines.
1) Paint Bubbles or CED bubbles :-
First of all CED is a continuous process. It's a non stoppable process. Whenever your conveyor getting stop this paint bubbles will come. this is a wet on wet process i.e. after dipping in ED bath it have mist spray to keep it wet, but some location are not covered in line, which show the Paint Bubbles issue.

D. Sharma
Paint Technologist - Aligarh,U.P., India




Q. We are doing E-coating for last 6 months and since last one week we are facing problems in the quality. Some lines appear after baking, and orange peel problems. The product doesn't have smooth finish, please help.

Ramakrishnan Iyer
Ganpath Electroplaters (Bombay) - Ludhiana-Punjab, Indian
September 28, 2018

Ed. note: Please forward photo of the problem to mooney@finishing.com for posting here.

A. Dear sir
For line mark, check your phosphate bath turnover ratio /pump circulation capacity.

Ganesh sonone
Technical services - Aurangabad, India
July 2, 2021




Q. I'm using BASF ED paint. I'm facing a problem that high gloss level even I adjust the Pigment-Binder ratio.

ASHOKBABU A
- Chennai, Tamil Nadu, India
December 2, 2018




Q. Hi, my name is Harikishan. How to increase meq and conductivity of CED paint?

Hari kishan
Unique coater - Faridabad, haryana India
December 4, 2018




Q. I want to know CED coating defects and its solution.

ABHISHEK Singh
Satyam auto - Kannauj,up, India
January 11, 2019


A. Hi cousin Abhishek. Please describe a specific defect, and include a photo and data about the situation that led to it, and I'm sure the readers will be happy to try to help!

Regards,

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




CED coating adheres to sheet metal but not if zinc coated

Q. Dear Sir,

My question is on Zinc coated parts coated in CED. When we CED coat on sheet metal after maintain all process parameter then the coated parts pass SST (960 Hrs.) and Adhesion test pass; but on Zinc coated parts coated in CED then the parts do not pass the Adhesion test or SST.

Alok

Alok Ranjan Pal
- Ghaziabad, Uttar pradesh, India
February 6, 2019


? Hi Alok. When you say "zinc coated" do you mean hot dip galvanized? Such parts must be properly zinc phosphatized after the galvanizing in order to be paintable.

Regards,

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


A. Hi, I feel the zinc coated part coating thickness is also contributing in this. Please check how much GSM it should be.

V Ganeshkumar
Engineer - Chennai, India
May 23, 2022




Q. Hello sir,
We are struggling the problems on Pretreatment and Electrode deposition process. After completing this process we are facing so many problems like lints, air packs, E.D. drifts, flow marks, ash marks, etc. So anyone can please give me any solution for this problem. And give some parameters on E.D. paint.

Manikumar Surisetty
Paint shop - Andhra pradesh, India
March 26, 2019




Q. Dear sir, after giving the coating in our bath, the coating is coming on half the tank. Conductivity of our anolyte is 1.500 and ED tank temperature .38

Himanshu Srivastav
- Fridabad harayanan India
September 14, 2019

A. Hi Fridabad. More words please. I'm not sure if you are saying that the vat which is holding your bath contents is getting paint deposited onto half of it or whether the product you are coating is a motorcycle fuel tank or similar which is being left half bare. Thanks!

Regards,

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




CED e-coating bubbles/holes? Defect problem on chrome plated surface

Q. Hello Dear,

I'm custom finish coater.
I'm also trying to do some cathodic electrophoresis process (applied over nickel and chrome plated small objects like door handles, etc.).

I'm facing problem as in images, during epd coating (in epd tank) I get finish that has many Little little bubbles like inside it. Those micro bubbles are like in surface.

My process:
Degrease alkali
DI Rinse 2x
Acid pickle
DI Rinse 2x
Epd tank
DI Rinse 2x
Cure

I believe my substrate is okay because nothing happens in powder coating process so I believe nothing should happen in e-coat either.

Rafal Kolbu
- Brwinow, poland
January 18, 2020


A. Hi Rafal. We did not receive the images/photos; please e-mail them to mooney@finishing.com.

D. Sharma suggests above that a line stoppage is a common cause of this problem. Can you tell us whether the defect happens all the time or only some of the time? Chrome plating is not meant to be e-coated to my knowledge. Are you sure that you have good, functional, adhesion on the chrome?

Regards,

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


Q. Hello,

That happens all time

I got detail movement in-tank. Chrome looks Good, also I tried stress relief before e-coat too and that did not work.

Have no idea what is that, because it looks like something tiny air inside or maybe it's something else.

I tried different temp, voltage snd time setting.

I tried also powder coating same detail - for that everything is okay. Only e-coat goes bad.

On raw aluminium plate I also get that strange effect.
In touch that surface is smooth but has that small dot everywhere appearance

I wonder what steps should I take to find out problem?

I'm sending defects photos to my post.

32574-5a   32574-5c   32574-5b  

Thank You

Best Regards,
Rafal

Rafal Kolbu [returning]
- Brwinow, poland


? Does this happen when you paint un-plated steel? I have seen where certain plated parts will outgas when e-coated.

Dan Mack
- Horicon, Wisconsin


Q. It happens on raw steel too.

Rafal kolbu [returning]
- Brwinow poland




Q. We are having Patches in CED Coating. Please suggest some remedy.

32574-6

Upinder Singh
- Ludhiana Punjab
August 1, 2020


thumbs up sign Hi Upinder. Thanks for the photo, but readers will probably need more data ... we'll see.

Luck & Regards,

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


A. Dear Upinder Singh,
It seems that your parts are "RUSTY" before coating & you have to clean the rust.

Avinash Vidhate
- Nashik, Mahatashtra, INDIA


A. The part was not cleaned properly, due to which such a problem has come, clean it and load it.

Ajay Verma
Line supervisor - Faridabad, India
September 11, 2021





Tip: Readers love to learn from others' situations!
Our experience since 1989 is that they tend to reply to actual situations but rarely respond to abstract questions.

Q. We are experiencing difficulties in CED coating of inside of square steel tubing. Is this common problem with CED and what is causing it?

Bogdan K.
- WINNIPEG, Manitoba, Canada
September 28, 2020


A. Hi Bogdan. It could be as simple as air in the tubing, or no solution transfer (meaning that yhe small amount of chemical in the tube gets exhausted, or they could just be too long. Can you provide dimensions? Thanks.

Luck & Regards,

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




CED part Quality Defect

Q. After CED Coating, have kept at oven around 175 degrees, when comes to Quality check we have found some paint dents, craters.

Its a Zinc plated part but no Passivation. Running the plan with the NVM of 14%, conductivity of 985.

CED coating has fisheyes 32574-7c CED coating has fisheyes 32574-7a CED coating has dents 32574-7b

Kindly suggest what's best to be done over the issue.

Sundaravanan Meganathan
- Chennai TAMIL NADU, India
October 28, 2020


A. Dear Sundaravanan Meganathan,
This seems to be FISH EYE problem. Go through fish eye problem on internet and you will find the answer.

Avinash Vidhate
- Nashik Maharashtra India




Q. Dear Sir

We are having a problem with CED coating. Our coating supplier always said the problem is coming from the material. However, it is not happening for 1 type of material but it happened in different material such as S55C and SPFH. We also unable to identify the actual defect on this CED coating. I am involving in metal stamping for automotive part. Hopefully, any expert in this finishing industry can help me to solve this problem. This defect really affects my production productivity.

32574-8a   32574-8b

32574-8d   32574-8c

32574-8e

Sulaini A. Rahman
- Selangor, Malaysia
December 28, 2020


A. Is this defect seen right after coating or after baking?
It might be due to temperature if it's after baking.

Amar Joshi
- noida India
March 5, 2021


A. Hi,
Sulaini A. Rahman: This problem occurred due to sheet surface defects called "pitting"; complain to your Raw material supplier and definitely it will resolve.
Thanks.

Dhirender Pratap Singh
Paintshop - Jaipur
April 29, 2022




Q. Hello I am Amar I am currently doing Cathodic electro coating (Ecoat)
Clear and Coloured one for jewelry and other mid sized items but the issue is I am getting wire marks on the product which seems to get rejected by the customer even though it's a small line
Currently using 0.3mm wire with typical coating spec 30 V 60 SEC 150 ° oven (have change a few specs but no positive so far) . Would really appreciate some advice on how to not get the mark.
Thank you

Amar joshi
- Noida India
March 5, 2021




Q. We are facing problem of shade variation in electrocolour (black colour). A little brownish colour obtained in every lot at same place (bottom side of bath) every time. what are possible reasons and solutions?

sandesh Raj
- aurangabad Maharashtra India
March 6, 2021


A. Dear sandesh
check DFT on both surface. Brownish shade will give less DFT.
Shade variation depends on:
1. Non volAtile material concentration. add Resin & pigment as per ratio. Ask supplier for ratio.
2. Set Voltage- Increase voltage & observe current.
3. Number of Parts loading, shape & loading position - change loading position ,if more parts loaded then Decrease parts quantity.
4. Number of anode working. Confirm anolyte circulation.
5. Ensure properly burned jigs used for good contact.

vishal ghawate
- Pune , India




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

Ajay Verma
Line supervisor - Faridabad, India
September 6, 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]




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
September 26, 2021




Q. In ED painting voltage dropping
Example: 180V we set but actual 80V.

suseendran mani
employee - Chennai, India
March 2, 2022




Q. Dear all, I am facing an ash mark issue on parts.

The part after CED and rinsing is found to be powdery after clearing off the water with air sprayer. The sensation of the surface of part is similar to touching powdered chalk.

32574-9b 32574-9c 32574-9a

We faced this issue just before the chiller was malfunctioning, causing the temperature of CED tank dropped to 20-22 °C for about 8 hours. I wonder if this event will cause irreversible damage to the CED tank?

Or this defect is more likely to be caused by pre-treatment line like impurities in acid etching and zinc phosphate tank?

Jayson Ooi
- Skudai Johor, Malaysia
May 28, 2022




Q. In Aluminum Casted and Machined components CED coated surface is not smooth and has dull finish. While doing reworking after coating removal some of the components become military green and after re-coating aesthetically not okay, others which gives natural aluminum finish becomes okay after coating.

32774-10

Please suggest suitable remedy.

Vishwa Deep
Quality Manager - Noida UP India
July 11, 2023


A. Hi Vishwa. Are you sure they were not 'military green' before you started (from chromate conversion coating)? Are the components different grades of aluminum? What are they stripped with? Is the main problem just the reworks not working well, or do you have a substantial number of rejects the first time around?

What is your pretreatment sequence? After stripping will the components be pretreated again or are you CED coating raw non-pretreated aluminum?

I am afraid that there may not be enough information in your posting yet :-(
Luck & Regards,

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




Q. Hi all, I am a newbie in CED coating. I am getting some problems with it. I pretreat aluminium profile bar with concentrated caustic soda solution, so that the solution attacked onto the Al surface and created some tiny holes on it. Please instruct me how to level these holes or cover it after CED coating without defects remaining in appearance.

Jame Pie
shop employee - Vietnam
August 3, 2023


A. Hi Jame,
I might be misunderstanding you, but it sounds like you are saying that the caustic soda causes some little dots of caustic, or reaction products, or such that are adhering to the surface and spoiling its smoothness. You will not be able to satisfactorily cover them; rather, you need to stop such garbage from adhering. Please talk to a supplier about a proprietary etch which will include chemicals such as gluconates designed to reduce such problems, and then try to improve your rinsing.
Luck & Regards,

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




Q. After baking paint brightness appearance is dull.
Also temp. is under specification.

Goutam prasad
- Jounpur, up, India
September 14, 2023


A. Hi Goutam,
Sorry but I can't understand your brief question. More words please regarding what you mean by "temp. is under specification".
Luck & Regards,

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




SUGGESTED E-COATING, CED, E-PAINTING BOOKS
for Shops, Specifiers, & Engineers


../abwd/ced3_electrocoats2020
"Electrocoat: Formulation & Technology" by Bruggemann & Rach (2020)
avail from eBay, AbeBooks, or Amazon

ced4_electrophoretic_deposition2017
"Electrophoretic Deposition (EPD)" by Nathan Bass (2017)
avail from eBay, AbeBooks, or Amazon

ced1_electrocoating2010
"Electrocoating: a Guidebook for Finishers" by Electrocoat Association (2010)
avail from AbeBooks, or Amazon

ced5_epainting1980
"Electropainting: A survey of principles and practice" by Reginald Leslie Yeates (1980)
avail from eBay, AbeBooks, or Amazon

ced2_electropainting1970
"Handbook of Electropainting Technology" by W. Machu (1978)
avail from eBay, AbeBooks, or Amazon
(as an Amazon Associate & eBay Partner, we earn from qualifying purchases)

Q. Hello everyone, kindly I would like to ask if you have ever experienced with CED and problem about rusty anodes?

We face a problem that our anolyte is totally rusty, containing 100-800 mg/l iron and it creates foam in the anolyte box. During summer maintenance we replaced totally rusty anodes but the iron still comes out, so we have to change anolyte weekly. What can be the cause of this? And why does it foam? The foam is very light and flies easily, can it be hydrogen foam ?

Elena Sedliaková
- Slovakia
September 24, 2023




Q. Dear sir,

I am new for CED coating process, I want to learn troubleshooting. Can you suggest?

Sathish kumar
- Hosur TN, India
November 10, 2023




Q. Hi, lately I am assigned to do research and development on CED. And lately my result is something like this picture.

32574-10

There are many dots in the surface of the working object. Maybe anyone here can help me what might be the cause of the dots?

Thank you

Josafat Malau
Employee - Indonesia, Jawa Timur
January 12, 2024





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