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topic 7863

Zinc Plating on 12L14 Steel (Blistering/Flaking)



2001

Q. I am a large volume zinc job shop. Periodically we experience difficulty plating certain CNC parts made from 12L14(leaded steel). The process is as follows: soak clean-electroclean-2 rinses-pickle acid 25% HCL-2 rinses-condition (first rinse after plating)-plating W/alkaline-non cyanide 1.0 oz/gal. Zinc 15 oz/gal NaOH, 3 to 6 amp. per ft2 -2 post plate rinses-sour .75%HNO3-clear, yellow or black dichromate. This customer manufactures all his parts (over 200) from 12L14, but only a very few (2) won't plate the first time through the process.We have skipped the cleaners skipped the acid and we still (may) have problems with these particular parts. We have run them once, pulled them off line, let them set 2 or 3 days and replate satisfactory. All other parts, stampings, CNC W/12L14, weldments. cold roll, hot roll, including parts from this particular CNC customer plate OK. There does not seem to be a logical explanation to the problem. WHAT AM I MISSING?

Don Penzenik
- Elkhart, Indiana


2001

A. You need fluoboric acid et al to activate the 12L14.

I believe your other parts may not have the best adhesion if all you are using is HCl.

tom pullizzi monitor
tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania 


2003

A. 1: Degrease
2: Electroclean Reverse current (rinse)
3: HCl pickle (about 10 seconds) (rinse)
4: 20% Fluoboric or sulfamic acid dip (30 sec - 1 min.) (rinse)
5: Plate

Scott J. Johnston
- Grand Rapids, Minnesota



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



2001

Q. We are zinc electroplating on machined 12L14 steel and we are experiencing blistering on the finish.

The zinc process is a rack operation, chloride zinc. When the parts are processed for the first time, the small blisters can be seen only with magnification (22X).

The parts had to be reprocessed due to the wrong chromate, and the second time these blisters are much more visible, with the naked eye. They are very small and uniform.

The chromate is yellow and we can see the blisters are grey in color. Each time we process again the parts, more blisters appear.

The 12L14 steel is known as a free-cutting carbon steel, resulfurized and rephosphorized, with the following compositions in %; Carbon 0.13 max., Manganese .85-1.15, Phosphorus .07-0.12, Sulfur 0.24-0.33 and Lead 0.15 to 0.35.

We are blaming the lead content on the steel. What is the best way to clean and process new parts? What can we do with the reprocessed parts? Are we bringing up (to the surface) the lead?

Any help will be greatly appreciated.

Enrique Segovia
- Monterrey, Mexico


2001

A. It could be the lead, but my guess is that you are etching out the large manganese sulfide inclusions that will be in the microstructure of this steel. Each time you reprocess, the inclusions are etched out to a deeper depth - thus increasing the severity of the problem.

larry hanke
Larry Hanke
Minneapolis, Minnesota


2001

Q. Larry,

Thank-you for your help. What preparation process do you recommend if this inclusions are manganese sulfide, as you mention.

Thank you again for your help,

Enrique Segovia [returning]
- Monterrey, Mexico


2001

A. Plating on 12l14 leaded steel. You can generally tell when you are dealing with it as any acid treatment to remove rust in a 50% HCl solution will cause it to gas and stink. But that treatment is held to a minimum and only as long as it takes to remove any rust. From that point I use a solution of 10% fluoboric acid for about 2 minutes to remove the oxidation from smeared lead on the surface.

Have had success plating electroless nickel direct on the surface or cyanide copper strike or plate. The plated parts pass all Quality tests including destructive testing.

Todd Huehn
- Blaine, Minnesota



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



Zinc Plate Flaking Off 12L14 Carbon Steel During Forming

2002

Q. I have a problem/question regarding zinc plate of 12L14 steel. We have a cylindrical case made of 12L14 that is zinc plated 200-400 microinches (our specifications). During the subsequent assembly process, we place a plastic cap into the case ends and roll the case ends using a pneumatic press and mandrel to capture the plastic caps. The rolling operation causes flaking of the zinc plate, which can cause electrical failures due to metallic particles inside the case. What are my alternatives to zinc plate that will not flake off during the rolling of the case ends, and what are the tradeoffs?

Mike McMonagle
- Houston, Texas


2002

A. Machinists love leaded steel. Platers hate it for exactly the problems you have. Normally, using a fluoboric acid dip will remove enough lead to give better adhesion. This is a more expensive acid and may have to be in addition to the muriatic or sulfuric the plater is using. Most tank lines do not have the capability of adding another acid tank and associated rinse tanks. Two main choices:
1. go to a NON free cutting steel or
2. go to a plater that can use the fluoboric treatment.

James Watts
- Navarre, Florida


2002

A. Maybe a more ductile plate? Try Zinc Iron... if the specification does not allow a plating change, are you getting it plated with acid or alkaline zinc? Are there cosmetic concerns for the finished assembly?

Brian Lucas
- Wolcott, Connecticut



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



2006

Q. WE HAVE A PROBLEM WITH PLATING RECENTLY, OUR PRODUCTS GET ZINC PLATE WITH YELLOW DICHROMATE THE MATERIAL IS 12L14 WE REQUEST THAT OUR PLATING THICKNESS BE .00015 TO .0003 ON ALL PARTS FOR YEARS IT WAS EXCELLENT. NOW THE PLATING BUBBLES AND SEPARATES FROM THE MATERIAL AND FLAKES OFF BY TOUCHING ESPECIALLY ON CORNERS WHY IS THIS HAPPENING THE PLATING HOUSE SAYS IT IS NOT THEIR FAULT IT IS OUR MATERIAL. WE HAVE USED THIS MATERIAL FOR 18 YEARS.

Buford Sparrowgrove
electronic and liner governors for off road use - Rockford, Illinois, US


2006

A. Steel varies from manufacturer to manufacturer and even between lot numbers from the same manufacturer. You are using leaded steel! An increase in the amount of lead from the minimum to the average amount is enough to have problems with plating. That said, the plater should be using appropriate chemicals to insure that the traces of lead are removed from the surface. If the plater took the job knowing that it is leaded steel, then it is up to them to properly plate it or prove that the amount of lead is out of specification HIGH. It is not being properly plated and the plater can not say that it is the steel unless he proves that it is out of spec. The fact that they plated it for 18 years without a problem does not negate his responsibility. If I were the plater, I would strip the parts and send them back to you with a "sorry". Basically, you will have to find a new plater or work with this one to make modifications to the line, which will mean a higher price.

James Watts
- Navarre, Florida



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



May 18, 2010

Q. Hello,
I have an ongoing problem with zinc-plated steel pipe that flakes AFTER crimping operations. Plating is not flaking before any material deformation. However, different lots of material will flake after crimping. We have reviewed the obvious culprits, like surface cleanliness before plating and plating thickness. I have noticed that higher concentrations of silicon (above 0.010%) had flaking issues, but the metallurgist doesn't think that's the issue. So, what else can I look at? The lot #'s with asterisks were the lots with adhesion issues.

Lead Sulfur Silicon
876475 .280 .310 .003 998853 .280 .340 .002
998995 .280 .350 .002
998995 .280 .350 .002 L1394H .270 .320 .011
35179108* .190 .270 .020
724006* .263 .319 .005

Dean Hustic
Quality Engineer - Solon, Ohio


simultaneous May 19, 2010

A. I will bet you a cheap cup of coffee that it is because you are using leaded steel. This needs a fluoboric acid activation step rather than HCl or sulfuric acid.
This removes some of the lead on the surface as well as activating the iron.
As for the silicon, I will guess that it is not perfectly alloyed in the steel and is existing in tiny pockets as silicon, which will not plate by conventional means.

James Watts
- Navarre, Florida


May 19, 2010

A. The smeared lead on the surface forms insoluble salts with sulfates and chlorides, you must dip in 30% fluoboric acid and enter the zinc "hot", or the very best you can do is to strike in zinc fluoborate and cover the lead, then the flaking will be minimized.

robert probert



Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
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May 20, 2010

A. It is a leaded steel.
You must have a 5% fluoboric acid dip prior to plating

sara michaeli
Sara Michaeli sara michaeli signature
chemical process supplier
Tel-Aviv, Israel



May 24, 2010

thumbs up sign Thank you so much for your responses! I know the platers "pickle" the parts, but I can't say for sure if the acid is fluoboric. Actually, I am thinking it's hydrochloric.
So, could this could also mean that different zinc bath chemistries (alkaline zinc and acid chloride) could also play a part?

Thank you so much!
Dean

Dean Hustic [returning]
- Solon, Ohio

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