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topic 4996

Root cause for Hard Chromium plating defects

adv.     u.s chrome

(2000)

Q. I have a hard chrome plating problem. Pits are found on a half inch dia. rod (tool steel) after the plating process. The density of the pitting holes is about 1 in every mm. They are not uniformly distributed around the rod. The pitting is about 200 micron in diameter at the chrome surface and they reduces the size to about 10 micron in diameter near the steel surface.

The thickness of the plating is about 300 micron. I am not sure the pit extends to the steel substrate, but it may be close (so the shape of the pit looks like looking at tornado(or bath tub or sink water drain vortex) in cross section).

Can any one experience this type of chrome plating defect and what can be the cause?This defect is too costly to me and not listed in books that I looked.

Don Bai
- Bloomington, Indiana


(2000)

A. Dear Mr.Bai,

There are several possibilities to solve this problem, but to be able to help you I would like to know a few things.

1. What current density was used?
2. What was the pretreatment of the substrate?
3. Do you use a wetting agent in your bath?

If the problem was caused by poor grinding, there is a trick that goes like this:

Take the part out of the bath after 5 minutes plating time, rinse it and polish the part with waterproof sandpaper 240, until you feel that the part is very smooth.

Rinse again and put the part back in the bath. Wait 5 minutes to be sure the part has the same temperature as the catalyst and than start plating again by slowly increasing the current.(start at 0 V.) Good luck,

Roel Jaarsma
- Netherlands


(2000)

A. A person can not really tell without seeing the part, but it sure sounds like gas bubbles .

As you can see, there is no obvious answer, buts lots of possibilities to check.

James Watts
- Navarre, Florida


A. Robert Guffie's Hard Chromium Plating suggests poor basis metal, improper cleaning, incorrect catalyst concentration, or incorrect fume suppressant. The Canning Handbook suggests particles of grease or stop-off wax or entrapped gas bubbles. Good luck with the troubleshooting!

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


September 14, 2011

Small pitting may be because of high reverse (etching) current or duration is high. Please review etching process.

ABHAYKIRTI T PAIKRAO
- India

(2007)

Q. I am working as chemist & metallurgical assistant in DLW (Diesel locomotive works) here in a hard chrome plating unit of cylinder liner. What type of precaution should be taken for good quality of hard chrome plating.

M Z Nadeem
plating shop employee - Varanasi, U.P, INDIA


(2007)

A. If you cannot retain a consultant to guide you, see if you can get a supplier of the plating process to visit you and go over your situation, MZ. If that is not possible either, try to at least get hold of the previously mentioned books. Many people, like Guffie, spent their entire careers trying to answer your question, and it simply isn't possible to even touch on all of the things that you must do for good quality chrome plating in the paragraph or two appropriate for a public forum. :-)

But describe a specific defect that you are encountering, and the operational parameters you are employing, and we will do our best to address it.

Good luck.

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


September 14, 2011

DEAR NADEEM,

FOR INTERNAL PLATING MOST IMPORTANT TO MAINTAIN ANODE CENTRE DISTANCE FOR UNIFORM PLATING AS WELL AS TO AVOID DEFECT IN THE CHROME PLATING. SECOND THING IS TO MAINTAIN TAPER IN ANODE FOR UNIFORM CURRENT DENSITY DISTRIBUTION.

DEAR RAJESH,
PLEASE EXPLAIN WHAT TYPE OF DEFECT IN PLATING. WE THINK THAT MS PLATING IS MOST EASY PROCESS IF TAKE PROPER PRECAUTION. IF ANY PROBLEM PLEASE VERIFY BATH CONSTANT, CURRENT CARRYING FIXTURE. MOST PROBABLY IRON CONTENT OF YOUR TANK IS HIGH; PLS CHECK

ABHAYKIRTI T PAIKRAO
- MUMBAI, INDIA


September 21, 2009

Q. Dear Sir,

We have facing the problem of hard chrome plating on MS pipe.
Whether chemical composition of base material affects plating process.

We are awaiting for your reply.

Regards,

RAJESH SANGAONKAR
QA ENGINEER - KOLHAPUR


September 21, 2009

A. Yes, Rajesh, it can. But it is only one of a dozen factors that affect the plating, and I think it's unlikely that it is the principal problem. Please try to explain your situation because people here would like to help you but are rather limited until you tell us in some detail what is going on. Thanks.

Regards,

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


July 11, 2012

Q. Sir
Can we avoid etching process in hard chrome plating?
Please tell effects.

I want to know about types of hard chrome plating defects.
A guideline book if available.
We are major hard chrome user on alloy steel round parts.

Dhananjay Patil
- india,Maharashtra,Kolhapur


Hard Chromium Plating

July 11, 2012

A. Hi Dhanjay.

I do not believe it is practical to avoid the etching process in hard chrome plating because this will result in insufficient adhesion. However, you could try it, and then test the adhesion with the modified Ollard apparatus (see letter 18002).

Keep your eyes open for affordable copies of Guffie's book as it is out of print and hard to find, but it is what you asking for =>

Regards,

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



Dislodged chrome on chamfered surface

January 2, 2014

Hi,

After chrome plating a cylinder, chamfered surface shows dislodged chrome. I need advice on this?

4996-1 4996-2 4996-3 4996-4

Cheers

Kabilan Chandra
- Singapore



Avoiding pre-plating and post-plating dents and damage to chrome plated piston rods

June 7, 2014

Q. Dear sirs
Can anyone suggest how to avoid dent and damages in piston rods before & after plating process completed?
Please kindly suggest your comments.

Regards,

Asvin kumar
- Chennai, India


June 2014

Hi Asvin. Please give us some hints about your situation. For us to just conjecture the many ways that the piston rods of the world, ranging from tiny to freight car size might be damaged or dented before or after plating, and suggest tactics to avoid it doesn't sound useful to you, or practical. Let's start with how they get damaged in your case rather than listing each theoretical way. Please get back to us on that.

Still, one thing I would say is that parts that are damaged or dented before they get to the plating step obviously should not be plated. So if you are seeing damaged parts being plated you need pre-plating inspection closer to the plating step. Good luck.

Regards,

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



Is this defect from chrome plating or from casting/heat treatment?

August 8, 2014

Q. We are seeing a defect returned from our plater as "customer defect". These parts are cast low alloy steel and receive a quench and temper. We run these parts in large lot sizes and have a great level of control in the foundry. Each lot is heat treated by itself, in house. I am wondering if anyone has seen this type of defect before and if you could point me in a direction to nail the root cause. At the plater they see a 3 hour acid vibe before hard chrome plating. We have not changed the process on the casting side since last year and run a couple thousand a year. This issue seems to be affecting only a percentage of the lots - but not every lot. This is leading me to believe that it may be occurring during plating - which runs in smaller lot sizes than what we produce them in. The parts are racked for plating on two holes - one on either side of the picture just outside the frame - we do not generally see the defects in this area.

4996-1thumb 4996-2thumb 4996-3_20Xthumb 4996-4_20Xthumb 4996-5_50Xthumb
(Click on thumbnails to see high resolution photos)

The last pictures are after the the parts have been stripped and polished and under magnification.

Sean Marek
Process Engineer - Wisconsin, USA


August 10, 2014

A. First things first, let me qualify what I'm about to type here before I get started. I am not a metal caster, nor am I a chrome plater. I'm an anodizer with almost 30 years of experience. With that being said, from the pictures it does look like a substrate issue.

The reason I'm replying in this unfamiliar section is something that you typed in your question:

"We have not changed the process"

If I were a part of a set of triplets, all 3 of us together would not have enough fingers and toes to count up the amount of times I've heard this phrase. Hell, I've even used it myself.

Sure, it very may well be that you have not changed the process, but what you need to be asking/saying to your self, has something IN my process changed? And you answer that question by starting at step one, and verifying all of the parameters that you process by, are indeed meeting your internal specifications, all the way through the last step. During this step by step trouble shooting process you may find that yes, you are operating within parameters, but for some reason, perhaps one of your steps is operating at the higher, or lower limit of your process parameters..and you will learn a lesson that your specs need to be tightened up.

Unfortunately there is a lot of this (finger pointing) that will go on between coaters, and manufacturers. And you will hear the phrase I quoted quite often. It's a shame, as both of you have the same end goal....a quality product. If both sides sit down and take a hard, detailed look at their process, a reason for the process shift/defect can normally be found.

Diatribe complete, thank you for your time. Now, perhaps someone in this forum with experience in casting and/or chrome plating may be able to point you toward a cause of the defect you are seeing. :)

Marc Green
Marc Green
anodizer - Boise, Idaho


August 12, 2014

Q. I say we have not changed the process because the first question asked otherwise is:"If this hasn't happened in any of the previous lots then what changed in the processing of this lot?" I have access to a large amount of data throughout the processing of the part on my end, I have spent hours sifting through the information I have, observing microstructure, and digging into anything we believe may have resulted in this defect. Nothing stands out. That said, I have taken the time to go to my supplier and sit down with them. The end goal for both of us is getting quality parts out of the door, but we need to figure out the root cause of this defect. Has anyone seen anything similar to this?

Thanks in advance.

Sean Marek [returning]
- Milwaukee, Wisconsin, USA


September 2, 2014

A. I'm not sure if 3 hour acid vibe is a typo or not. I've never heard that term.

However, looking at the pictures, it almost looks like you have inter granular attack occurring on the surface. Chrome plating is a negative leveler so the more chrome that is plated onto the surface, the more pronounced your defect will be.

If a 3 hour acid vibe is actually a 3 hour acid soak, the acid may be too strong or not inhibited and is causing an attack on the surface material.

Justin Brooks
- Rock Island, Illinois



August 25, 2015

Q. Dear sir,
I'm working in hard chrome coating for solid rolls and hollow rolls that is used in Steel Line (CGL, CRM). Now we are facing so many problems during coating: like rust after chrome coating; coating speed as compared to previous speed is 50% down; some portions cannot be coated on work piece.

Please give me valuable result for this problem.

ACRONYMS:

CGL = continuous galvanizing line
CRM = cold rolling mill

VISHAL PATIL
STEEL - Maharashtra, INDIA


Trouble in Your Tank
by Larry Durney

August 2015

A. Hi Vishal. The Hitchhiker's Guide to the Galaxy says "Don't Panic" ... and that's the "First Rule" of the twelve rules in Larry Durney's "Trouble in Your Tank: Handbook for Solving Plating Problems". The implication is: don't flail about, wildly changing everything, because you'll surely just make it worse.

When there are a whole host of problems, experience counts and I would strongly urge you to locate a chrome plating consultant in your area. Often a few minutes of his/her walking the line to spot what is obviously wrong, and doing a couple of quick titrations, can quickly solve the problem. But if you want to try to fight you way through it, all of the problems you mention could be related to a simple solution imbalance ... so tell us what you can about the solution analysis. Thanks.

Regards,

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



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