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topic 39257

Remove Boron Nitride Coating from Stainless Steel?


A discussion started in 2006 but continuing through 2017

2006

Q. Hi All,
I am a doing a company project/thesis. Our current method of cleaning dies made of 300 series Stainless Steel is benching. It is an ergonomic headache, and causes too much die wear. We are trying to remove a coating consisting of T-50 and boron nitride that is exposed to temperatures up to 1600 °F and are looking for an alternative method that will be easier on operators and increase die life while cleaning of the coating. I have been researching this topic and have found that CO2 blasting, Ultrasonic cleaning, and plastic bead blasting are some of the best cleaning methods for this situation. I am hoping someone can enlighten me as to the real world results these methods produce or any drawbacks to these methods. Any other suggestions are also welcome. Thanks in Advance.

Archy M [last name deleted for privacy by Editor]
Job Shop Employee/Student - Lansing, Michigan


2006

? What is benching?
What is T-50?
Is the boron nitride the white, lubricative (hexagonal) or the hard (diamond cubic) type?

If T-50 is an alumina binder for the BN, it may dissolve in hot caustic solution (aq.).

Ken Vlach
- Goleta, California
contributor of the year

Finishing.com honored Ken for his countless carefully
researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work
which the finishing world continues to benefit from.



2006

A. 1-BENCHING: Infinite spending hours sitting on a "bench" hand working something.
2-BORON NITRIDE: I didn't know there were 2 types. Thanks for the quote Ken. I always learn from you.
3-T-50: I'm lost too. Please enlighten us, Archy.

Guillermo Marrufo
Monterrey, NL, Mexico


2006

Q. To Mr. Vlach & Mr. Marrufo, I hope the following will answer any questions you have; I apologize for the delay and greatly appreciate your assistance.
- Benching is also referred to as manual grinding. We are using an abrasive media powered by an air motor to remove material on the part, thereby also removing the coating consisting of Formkote T-50 and Boron Nitride.
- Formkote T-50 and Boron Nitride are lubricants used in conjunction to ensure parts do not stick to the die in high temperature and pressure.
- The Boron Nitride is a white powder and it has a hexagonal crystal structure.

The following information is from the MSDS for each product.

Formkote T-50 Info

Chemical Names and Synonyms: Solid Film Lubricant
Chemical Family: Not applicable
Formula: Complex mixture

Formkote T-50 Composition
Components %
Graphite 1-10
Xylene 1-10
Toluene 30-40
Ethyl Acetate 20-30


Boron Nitride Info
Chemical Name: Boron Nitride
Synonyms: N/A

Boron Nitride Composition
Components %
Boron Nitride > 95
Boric Oxide > 5


Archy M [returning]
- Lansing, Michigan


2006

A. Depending on the thickness of the coating (which you didn't mention) you may want to try with several successive combinations of sand blasting with coarser-to-finer grades (i.e. 60 or 120, then 240 silicon carbide). This normally removes most stubborn hard coatings. Then No. 12 glass-bead blasting or a similar mesh of rounded steel shot blasting to leave a semi-bright surface ready to work. Chemical strippers may exist but will involve dangerous materials and complicated disposal issues. Does your coating have a different color than the base steel? This helps.

Guillermo Marrufo
Monterrey, NL, Mexico


2006

Q. The avg. coating thickness is .001"-.002" , while max thickness is around .003". I would consider the coating a different shade of the base steel, rather than a different color, though the shade of the coating is dark enough that it is a distinct difference.

Archy M [returning]
- Lansing, Michigan



Cubic Boron Nitride removal/stripping

December 17, 2017 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi all,
I'm trying to find an efficient way to remove a Nickel CBN (Cubic Boron Nitride) coating.
The problem is that the CBN coating remains completely or partly.
I use 30-50% volumetric nitric acid solution or even 70% acetic acid + 30% nitric acid, but it works only on some parts and not on all of them.
I also tried heating the solution to 35 °C and/or using mechanical agitation.

Thanks in advance.

Arik Strom
- Petach Tikva, Israel


Metalx nickel stripper
... plus Cufix E Copper Stripper, TN-64 TiN Stripper
& Strippers for Tungsten Carbide in Cobalt Matrix

December 2017

A. Hi cousin Arik. I'm not sure what nickel cubic boron nitride is. Are you speaking of an electroless nickel plating with occluded CBN particles? Or is this something else? If it is electroless nickel, I think the chemicals and procedures normally used to strip electroless nickel plating will work. What is the substrate material?

Regards,

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


December 18, 2017

Q. It is nickel plating with occluded CBN particles but it is not electroless nickel. the substrate is nickel or titanium.

Arik Strom [returning]
- Petach Tikva, Israel


December 2017

A. Hi Arik. Nickel strippers ought to work then, but remember that the stripper doesn't "know" and can't act upon your wish to remove the nickel plating but leave the underlying nickel unscathed. To them, nickel is nickel :-)

Regards,

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



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