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Ted Mooney, P.E. RET
Pine Beach, NJ
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Repair of hard chromium plated parts
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Q. Q. Received one roller with Dia of 250 mm, it's too much got idea to do turning that will cause 2 mm downsize , my question is any other solution?
Ammar Mohamed Elamin Mukhtar- Saudi Arabia Jeddah
December 11, 2023
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Q. Looking for chrome spot plating procedures and equipment for repair of defects (pits, voids, pin holes, etc) in chromium plating deposits.
J.F. Tucker1998
A. Defects in Hard Chromium Deposits, by Chessin, Knill and Seyb, of M&T Chemicals now Atotech, presented June 30th, 1981 during Sur/Fin '81, has welding, plugging, detection and inspection, polishing, etc. a 30 page booklet. Atotech continues their work on hard chrome so there may be new papers.
Contact AESF or Atotech USA for reprints of the paper.
Tom Pullizzi
Falls Township, Pennsylvania
Ed. note: This paper is presently on line courtesy of Products Finishing magazine: Part 1, Part 2
Hard chrome to rebuild internal dia. of cast iron housing?
Electrochemical Metallizing by Marv Rubinstein
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Q. We are a machining unit; we need advise in case ci/sg iron bearing housing's id need to be reworked. During machining one of our batch has been rejected by id going oversize by 15 micron (approx. dia. 230 mm material sg iron grade 500/7). Is it possible to hard chrome it and regrind id ? What is maximum coating of hard chrome that can be deposited on id? Is it effective in casting in same way as is steel? Is some other technology available for these type of problems?
regards,
machine shop head - Chandigarh, India
March 11, 2009
A. That is actually a bit thin. In the aerospace industry, 45 microns is a common minimum per side for chrome. Thinner leads to peeling problems. The grinding setup has to be nearly perfectly the same as the original grind so as to not have a very thin side and a thick side.
James Watts- Navarre, Florida
A. In light of James' comment, perhaps you should machine it out a bit more oversize, so as to allow the preferred minimum thickness of chrome to be used.
Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
A. Brush plating may be another option. The process is portable and is frequently used without post machining or grinding operations since the equipment and chemicals are designed to accurately control the required plate thickness. Get in touch with a reputed supplier or a good service shop that offers this process. Some of them advertise here.
Guillermo MarrufoMonterrey, NL, Mexico
Brush plating of chrome is only used for a cap coat as you can not apply it in a thick layer. This can be put on over a hard nickel layer that you can use for build up.
Also quality brush plating is highly dependent on the operator and the speed that you can swap "brushes".
- Navarre, Florida
Jim,
I agree with your statement, but I never mentioned chrome. The guy is talking about mis-machined nodular iron parts. Brush plated neutral or slightly acid nickel would be my choices. Fifteen microns? No problem, piece of cake, plated to size.
Best regards,
Monterrey, NL, Mexico
I agree with brush plating it with nickel. The original post said chrome and I assumed that is was for a reason.
As far as a piece of cake, That remains to be seen. If the part can be rotated and a continuous flow rig is used, I will agree. I assume that since it is a bearing housing that it has at least one flange to get in the road. I have seen some really bad brush plating by people that thought that they were good. I also have seen some extremely difficult bearing housings on large parts.
With proper training and good equipment, brush plating is a great way to go in many cases.
- Navarre, Florida
March 24, 2009
A. We have salvaged items like yours by doing ENP, wherein you can control the size
Prashant Soman- Dist. Thane, India
March 22, 2009
Spot Repair of Continuous Casting Molds
(We have many other threads about Continuous Casting Molds -- Please search the site
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Continuous Casting by Wolfgang Schneider (2000)
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Continuous Casting:A Revolution In Steel by A. Heinrich Tanner (1998)
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Continuous Casting of Steel by W.R. Irving (1993)
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Continuous Casting -- 5 Volume Set by A.I.M.E. (1983-1988) avail from eBay,
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Q. We have a continuous steel casting industry and use a water cooled copper mold tube that was chromium plated a few years ago; but its coating has failed at a few points now. Can you help us for repair of this mold? Should we remove that coating completely or can we repair that coating locally?
product designer - Isfahan, Azadi, Iran
January 24, 2011
A. Hi dear
you must remove old plate and plate that again .
- Lagan, France
A. Hi Fardin,
First check with your customer that you are allowed to carry out local repairs. If it is allowable then I would suggest you contact one of the suppliers of brush plating solutions and equipment such as Sifco or Metadalic and seek their advice about an acceptable repair scheme. They will be able to tell you what preparatory steps are necessary and what the best plating solutions are. They may well come on site (if it is at all possible) to assess what needs to be done.
Alternatively seek out a treatment company that offers the service of brush plating and see what they can do for you.
Aerospace - Yeovil, Somerset, UK
A. Chrome plating by brush is difficult and is thin. This means that most of the hole must be filled with nickel or cobalt or similar. Now it must be ground back so that you can get the thickness of chrome on it and not have it removed when you polish the mold back out.
I have seen a rig for spot chrome application, but it is fussy and messy. Most companies will not allow it to be repaired.
Strip and replate or strip and go to an appropriate high energy thermal spray is probably the simplest route.
- Navarre, Florida
January 31, 2011
A. Hi Fardin,
It would be more practical to remove these copper molds, grind it and redo the Hard Chrome Plate. Yes, selective plating can be applied but there occurs a mismatch of Old and New plating and brush plating is very thin. Choice is yours. Good Luck.
ELECTROPLATERS - BELGAUM KARNATAKA INDIA
A. I agree with Mahendra that replating is a better idea. There are few plating problems which can involve as costly a mess as a defective plating job on continuous casting molds :-)
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Please see also --
• Topic 5399 "Brush Plating vs.Tank Plating of Decorative Chrome"
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