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Anti-galling coatings. Can plating solve our galling problem?



Q. I am with the University of Texas, Center for Electromechanics, and I was hoping that you could help me with some information. We have a problem with two shrink fitted parts (a hub onto a shaft) galling on us when we take them apart. We thought that a plating of some sort would help with this problem. The plating will need to be able to withstand 50 ksi compression, and the parts are made of AISI 4340 steel, HRC 46. We are also needing to have a friction coefficient of about 0.15 between the parts, and the plating must be able to withstand temperatures up to 700 °F. Is this possible, and do you have any general information on compression strengths and/or threshold galling stresses, operating temperatures, and friction coefficients of platings, or any other suggestions? Thank you very much.

Michael Lewis
- University of Texas at Austin-Center for Electromechanics - Austin, Texas
1998


A. I do not have numbers, but adding electroless nickel to ONE of the two parts will virtually eliminate the galling you are experiencing. It has excellent lubricity, can stand the temp you mentioned, and is a very uniform coating that if put on by someone really good, you probably would not have to grind or hone after plate if the parts are properly sized to start (allowing for the plate).

James Watts
- Navarre, Florida
1998



1998

A. Michael,

In the vacuum industry plating silver on threads, etc. is commonly used to prevent seizing and galling between metal parts. This might work for your application.

Donald M. Mattox
Society of Vacuum Coaters
Albuquerque, New Mexico
Donald is the author of:
"Handbook of Physical Vapor Deposition (PVD) Processing" (2010) [on AbeBooks or eBay or Amazon affil links]
and "The Foundations of Vacuum Coating Technology" (2018) on AbeBooks or eBay or Amazon affil links]



1998

A. In plating I think the resistance to compressive forces is generally referred to as hardness. Most plating is rated on Rockwell C (HRC) or Vickers hardness (HV)scales. However, you also have to look at adhesion when talking about resistance to compressive forces.

The coefficient of friction on a plated surface will depend largely on prior surface preparation. Generally, if you have a rough surface prior to plating -- you will have a rough surface after plating.

Silver plating gives you a surface that provides lubricative and anti-galling properties. It can withstand temperatures up to 1200 °F. However, it may not be adherent enough to withstand the compressive forces you write about.

Nodular thin dense chrome plating is also a good anti-galling/anti-spalling coating that can withstand temperatures above 700 °F. It is harder (~ 1000-1200 HV or >300 ksi) than silver plating and may suit your application. It is strongly adherent to basis metals such as 4340 and is extremely resistant to wear and abrasion. However, this a proprietary process owned by Armoloy Inc.

You may also check out nickel plating.

In parting: A good test is better that a thousand opinions.

Greg Haataja
helicopters - Fort Worth, Texas



sidebar

"The Properties of Electrodeposited Metals and Alloys"
by William Safranek

on AbeBooks

or eBay or

Amazon

(affil links)

Q. I would like to know the Rockwell hardness or the Vickers hardness of electroplated nickel.

Chris Ropoulos
JADCOM - Fremont, California
2000



2000

A. There is no single value, Chris, not even a narrow range, but Safranek's "Properties of Electroplated Metals and Alloys" has 70 pages of data on the properties of nickel electroplated under different conditions, and another 50 pages on nickel alloys and composites.
If you need detailed data, it's a great source.

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




Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)



Q. I AM LOOKING FOR A COATING TO USE ON A VARIETY OF THREADED STAINLESS STEEL PARTS TO PREVENT GALLING. THE PARTS ARE DISASSEMBLED/REASSEMBLED IN THE FIELD ON A REGULAR BASIS FOR REBUILDING AND CLEANING. CAN YOU SUGGEST A COATING OR PLATING THAT WE CAN HAVE APPLIED TO PREVENT THIS FROM HAPPENING?

MIKE RUFENACHT
- MINNEAPOLIS, Minnesota
1999


A. Teer Coatings in England has a graphite-based PVD coating that might fit the bill. I think they market it in the U.S. through Multi-Arc.

jim treglio portrait
Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California

1999


A. One of your best options is Electroless Nickel. It prevents galling, you could also use ENi with Teflon so that assembly/disassembly will be easier to perform.

Enrique Segovia
- Monterrey, N.L.
1999


A. Silver is the standard non-galling coating for the vacuum technology business. Silver coated bolts are standard items.

Donald M. Mattox
Society of Vacuum Coaters
Albuquerque, New Mexico
Donald is the author of:
"Handbook of Physical Vapor Deposition (PVD) Processing" (2010) [on AbeBooks or eBay or Amazon affil links]
and "The Foundations of Vacuum Coating Technology" (2018) on AbeBooks or eBay or Amazon affil links]
1999


A. I used to use a chromium plating called ARMOLOY NTDC where I worked previously. Armoloy is an American company (Philadelphia I think). The coating is extremely hard, (about 70HRC / 1100HV), satin in appearance, and works wonders. In our experience it adhered and lasted much better than either Nickel or Silver. We used it for Nuclear applications mainly, where exfoliation of Nickel had been a problem.

Wayne Ward
- England
1999


A. Carpenter Steel makes an austenitic stainless steel called 'Gall Tough' which works well. There is a competitors product called 'Nitronic 60'

Steve Cassidy
- Hudson, Massachusetts
1999


A. If silver plating is not used, there are lots of different dry film lubricants, which are affordable solutions, particularly the ones that come in a spray can and do not have to be baked. They are not as good as baked, but would work fine for a touch up.

James Watts
- Navarre, Florida
1999


A. Mike - Another anti-gall coating is manganese phosphate. It also holds an RP [rust preventative] oil very well for corrosion protection. The production process is similar to zinc phosphate. Ask your chemical vendor for info.

Dan Brewer
chemical process supplier - Gurnee, Illinois
1999



A. We provide and train customers for Anti-galling copper plating on all types of premium and non-premium box or pin connections on tree-tops, tubing hangers, top/bottom subs, cross-overs, blast-jints test caps, drill collars, etc.

Major licensors uses this process for Anti-galling reasons.

Sunny Tan
- Singapore
February 10, 2010


A. RIE Coatings supplies coating #1713, often topcoated with #4606 for SS fasteners

Chad D. Petersen
- Jackson, Minnesota, USA
June 4, 2014


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Ed. note: Gentle readers, this is a service for technical information and camaraderie, and is only made possible by advertisers whose support will certainly evaporate if the forum is used not for those purposes, but to steer potential customers away from them and towards other vendors. Further, although companies like free favorable publicity, we sometimes hear from their lawyers over unfavorable publicity -- so public recommendations of brands tend to be unrealistically favorable. Finally, shills have posed as satisfied customers and posted glowing reviews of brand name products :-(

Therefore, please try your best to answer as technically and generically as the situation permits, avoiding brand names and sources to the degree possible. Thanks!



Q. I NEED TO CROSS REFERENCE THE SPEC BELOW; PLEASE HELP: ANTI- GALLING COMPOUND PER PWA-36545-1

Laszlo Kocsis
- Tullytown, Pennsylvania
2002




A. Hi Laszlo. I can tell you that PWA stands for Pratt & Whitney Aircraft division, but not much more.

Regards,

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


A. Go to the Everlube Products website and they produce a product that conforms to PWA 36545. It is either Everlube 620C or Esnalube 382, I don't remember which one it is. The site also has information on application of product and MSDS.

Scott Canning
aerospace engineer - Laconia, New Hampshire
July 1, 2014




Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)



Finishing of threads, 17/4PH or 13% Cr parts

Q. Will I introduce a potential corrosion problem if I use silver to coat the threads of parts made of these materials? We have a problem with fragile threads when assembling or disassembling parts made of these materials, and I would welcome any advice regarding this problem.

Jan Habrekke
BTU AS - Trondheim, Norway
2005



A. Try Armoloy TDC coating. We apply a coating that is used for anti gall applications on 17 4 and provides a good corrosion resistance.

Jed Chamberlain
Armoloy - England
2006

ACRONYMS:

TDC = Thin Dense Chrome



thumbs up sign Thanks Jed. We try to not recommend one proprietary over another in this forum. But please explain why you feel that hard chrome plating might be a good or better alternative to silver plating. Thanks again.

A. Hi Jan. It is a commonplace to silver plate threads of stainless fasteners to minimize galling issues, although it is not the only potential solution to the problem. To know whether you might have a corrosion problem would require knowing the severity of exposure conditions plus the other materials of construction in electrical contact with the silver plated stainless fasteners though. Good luck.

Regards,

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




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