[How do I?] Protect Black Oxide Finish

[EmilioG]

How can I protect the black oxide finish on my new tools and the knurling? They seem to wear away quickly. Thanks

 

[joshua43214]

The black oxide finish is the protection. If it is wearing away quickly, then it is probably poorly finished (or it is just a high wear tool).
What kind of tool are we talking about?

It would take me months to penetrate the oxide finish on my Snap On Sockets, and even my oldest and most used ones still have traces of it. I would pretty much always wear out the socket before the finish would wear off.
The finish on my Chinese tools in the metal shop seems to practically rub off some times. I just chalk it up to being too poor to buy better tools.

 

[kd4gij]

Not much you can do with the light coating they put on some of this stuff. Except re do it with one of the systems out there. Member Ray c. did a nice wright up on here a phew months back.


Edit: I found the thread. Read " Ray C" post in this thread.
http://www.hobby-machinist.com/threads/black-oxide-coating.22707/

 

[Wreck™Wreck]

How can I protect the black oxide finish on my new tools and the knurling? They seem to wear away quickly. Thanks

You don't, black oxide is not a durable surface finish, it works well (and is inexpensive) in order to keep parts from rusting between manufacturing, shipping to a wholesaler and then to the end user. This may take months or years depending on how much product is moved. If your major concern is appearance have the BO stripped and the tools hard chromed, I do not recommend this approach however as these are just tools used in making the product and are mostly kept out of the elements, hard chrome also has it's own problems. TIN coating is a viable alternative to chrome, many people in the auto,motorcycle,gun hobbies also love the gold color of TIN coating.

 

[4GSR]

If you want something that won't wear off for the next 300 years? I can get a process done called "QPQ". It is a salt bath nitriding process that will give you a nice deep black finish when done. Surface hardness is around 70 HRC! It's not cheap!

 

[Wreck™Wreck]

An alternative to hard chrome? Sounds very interesting, we send parts out daily for chrome, QPQ may be an alternative. Is it FDA approved for human food contact.
Titanium Nitride coating has not been as far as I know at the moment.
I have a friend that is an engineer in the Pharma packaging business, several years ago they were developing a process to fill pump top bottles with toothpaste for Consumer use. Several fixed displacement product pumps wide per line, hard chromed stainless pump pistons. His problem was the abrasive in the product, (toothpaste is just slightly less abrasive then lapping compound) would damage the pistons in short order. Being the simple machinist that I am I inquired if TIN coatings over carbide would work. They will however neither material was FDA compliant at the time so unusable in practice.

 

[4GSR]

QPQ may be acceptable. but I doubt it. But there's nothing to the hardening process or the coating that could contaminate food product in use. The drawback would be the wash down of food processing equipment after use. Once dried, it could produce rust IF a food grade oil is not applied. But I have seen parts with the QPQ process done to them that have been out in the weather for a couple of years without any rust started on them. QPQ use in the oilfield will hold up to brine for quite a while before corrosion sets in. It is less likely to be attacked by H2S which is seen in the field, too. Ken

 

[EmilioG]

The black oxide finish on some Starrett tools and Albrecht chucks seems to wear away.
I suppose it's only temporary but it does look nice, the contrast of black and shiny metal.
Just wish I could preserve it.