# black oxide vs bronze oxide drill bits



## brianford (Mar 28, 2011)

what is the use for each of these?


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## Just Bill (Dec 21, 2008)

Black oxide is simply high speed steel with a rust resistant coating. not sure what bronze is. High speed steel is at the bottom of the wear category for drilling anything but wood. Works well in soft steel. As the coatings or materiels progress upward, titanium, cobalt, carbide, are for drilling harder materials.


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## rossfingal (Mar 20, 2011)

I think what brianford is referring to when he says "bronze oxide" is -
titanium or cobalt (from how some of them look).
Bronze would be a "little" soft.

rossfingal


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## brianford (Mar 28, 2011)

No, They are called specifically "Bronze oxide drill bits"


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## brianford (Mar 28, 2011)

judging by the previous post and some more research i have done this morning the bronze oxide "gold" is a surface coating to allow extremely high speed drilling (intended not only for wood) without causing friction heat build up


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## Daniel Holzman (Mar 10, 2009)

The definition of bronze is an alloy of copper and tin in various proportions, sometimes with traces of other metals. Bronze is a soft alloy, and is useless for drilling anything hard like steel. The term "bronze oxide" probably refers to the color of the coating, as copper oxide or tin oxide are also quite soft, and would not be useful as coatings on high speed drill bits, unlike titanium, cobalt, or various nitrides, which are quite hard. Similarly, the term "black oxide" seems to be a generic term for an oxide coating on the bit to protect the underlying high speed steel from damage, although certain oxides are harder than the native metal from which they are derived.

I could not find a rigorous definition of either black oxide or bronze oxide. By the way, I buy titanium nitride bits, expensive but hard as hell.


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## beerdog (Dec 10, 2008)

Most drill coatings are intended for production environments. Specifically for metal working. The benefits are not as significant for a carpenter or DIYer. The variety of tooling coatings is very large. Every coating has an intended application. They offer significant benefits when making thousands of parts such as faster speeds&feeds, longer tool life, lower heat, better finishes, and better chip ejection. If you are working arround the house just get HSS or ones with a basic coating like black oxide, TiN (Gold), or what ever is readily available. I would not spend alott on a coating because you cannot control the cutting environment like a factory and will burn, chip, or break a drill long before getting the value out of an expensive coating. 

Note...you cannot avoid heat build up on a drill. Coatings simply lower it due to reduced friction at the cutting point and as chips are ejected up the flutes.

If you are drilling metal simply add a little cutting oil to drill. It makes a HUGE difference. When drilling woods, don't run the drill at max speed. Wood requires lower speeds. Think about those old hand drills.


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## beerdog (Dec 10, 2008)

I spent alott of time in machine shops as a machining and tooling engineer. People write books about and get PhD's in this stuff. Here is a quick link I found. There is a ton of stuff out there on tool coatings.

http://www.icscuttingtools.com/surface.htm

Why do you ask? What are trying to drill through?


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## nap (Dec 4, 2007)

> =Daniel Holzman;619160]The definition of bronze is an alloy of copper and tin in various proportions, sometimes with traces of other metals. Bronze is a soft alloy, and is useless for drilling anything hard like steel.
> 
> , although certain oxides are harder than the native metal from which they are derived.


 sure glad you got to that last part. For a minute I thought I was going to have to bring up aluminum oxide. Aluminum oxide is much harder than the base metal aluminum and withstands much more heat before melting. 






> I could not find a rigorous definition of either black oxide or bronze oxide. By the way, I buy titanium nitride bits, expensive but hard as hell.


http://www.icscuttingtools.com/surface.htm

and if you want a hard bit, get a carbide bit (not tipped, the whole bit).

dang dog, ya beat me to it. I was off looking up a bunch of crap only to post and see you linked the same site as I had found.


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## brianford (Mar 28, 2011)

beerdog said:


> I spent alott of time in machine shops. Peopel wtite books about and get PhD'sin this stuff. Here is a quick link I found. Ther ei a ton of stuff out ther eon this stuff.
> 
> http://www.icscuttingtools.com/surface.htm
> 
> Why do you ask? What are trying to drill through?



I ask because i got a set of about 100 drill bits as a gift. There were black oxide bronze oxide masonry spade bits tile bits drivers etc. I always use the back oxide bits b/c thats what i have always bought for an all around bit. I was in my workshop the other day and realized i had a pristine set of never used drill bits at my disposal and never really though about what they were for.


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## beerdog (Dec 10, 2008)

Black Oxide is a great all-arround metal drilling bit. I never heard of bronze oxide, but I imagine it has a target applicaion. Could also just be maketing at its finest.


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## nap (Dec 4, 2007)

beerdog said:


> Could also just be maketing at its finest.


Look at the link you, and I, posted. I believe it addresses bronze oxide and yes, it would appear to be a marketing tool.


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## beerdog (Dec 10, 2008)

nap said:


> and if you want a hard bit, get a carbide bit (not tipped, the whole bit).


Although it is one of the hardest tools, I would not recommend carbide drills unless you absolutly need it due to their cost. Carbide drills are very britlle and thus chip or break easily if the cutting process speeds (RPM), feed, drill angle are not precisly controlled. I used them all the time on CNC's with fantastic results, but any time I tried ot use them by hand they would chip immediatly.


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## beerdog (Dec 10, 2008)

I would not be suprised if there is broze alloyed into the coating for lubrication. I am a bit rusty on this topic these days. Soft materials like bronze, lead, sulfur etc are frequently added to steel to make it machine easier. They are referred to as free machining steels. They machine almost as easily as brass. The only drawback is they are very soft and can't be through hardened like a tool steel. They can be case hardened by introducing carbon (carborizing) into the surface and then heat treating it.


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## nap (Dec 4, 2007)

you missed the point. In the link, it does say it is more of a sales pitch than anything. 

this is from the "performance column" for a finish identified as:

Amber Finish Bronze Finish Gold Oxide

:

The goal of this heat treatment is identification and sales appeal, not performance. Gold Finish Tools perform the same as Black Oxide or Polished Finish Tools.

I suspect that is what all this "bronze oxide" is referring to. 

to the carbide bits being brittle and such; it was simply as a comparison to the TiN bits D Holzman was speaking of. TiN is a coating (a vapor coat applied lawyer approx .0001" thick) and as such, regardless of how hard it is, the underlying steel is just as important. After seeing how most people use a drill bit, I see little benefit to TiN coating as most people tear hell out of the cutting edge and simply continue to run the thing. At that point, there is little benefit to a TiN coated bit.

I did not intend to suggest using them as a general use bit. Personally, for most purposes, a black oxide or or some form of tool steel with no coating is adequate for most applications. I have never found a great benefit from TiN coated bits in general use.


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## beerdog (Dec 10, 2008)

I agree. Just don't know if I would accept just this web site. I used to have a library of tooling catalogs and reference material. Here is some stuff off PTD's website. Probably more drilling info than anyone should be subjected to. They talk a little about "bronze" arround page 10. They list it as a surface treatment resulting in a bronze color. A coating would then go over the surface treatment.

http://www.precisiondormer.com/sandvik/2531/internet/USA_English/s005481.nsf?OpenDatabase


Here is more. I used to read this stuff like people read great lierature.
http://www.precisiondormer.com/sandvik/2531/internet/USA_English/s005481.nsf?OpenDatabase

http://www.precisiondormer.com/sandvik/2531/internet/USA_English/s005481.nsf?OpenDatabase


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