Black Oxide vs. Cobalt Drill Bits

The debate about whether cobalt or black oxide drill bits are better has gone on for quite a long time, but the answer to this question is pretty simple.

In this article, we will review the two so that by the end, you can make an informed decision about which one to use on your next project.

Before that, let us define them both. Shall we?

What Is a Black Oxide Drill Bit?

A black oxide drill bit is a high carbon steel accessory that has undergone a heat treatment process to harden the surface.

Black oxide drill bits are moderately hard and easy to sharpen and they cost less than cobalt drill bits. These properties make cobalt-tipped drill bits ideal for drilling in softer materials like wood and plastics. They can also be used for drilling in moderately hard materials like cast iron and mild steel.

What Is Cobalt Drill Bit?

Cobalt drill bits are cobalt-based alloys that have been heat-treated to increase hardness and strength. These drill bits are harder than black oxidation bits, but not as hard as high-speed steel or titanium nitride coated bits.

This makes them perfect for drilling in hard materials such as stainless steel and high carbon steel.

Black Oxide vs Cobalt Drill Bits: Make your Decision


You are probably wondering what material between the two will cut better. The thing is that ultimately, it depends on what you prefer.

You see, cobalt drill bits tend to be harder than black oxide drill bits, and that makes them perform better when cutting through tougher materials like steel.

The irony is that they can break when used on softer materials like wood or plastic.

On the other hand, black oxide drill bits will not cut through as many different types of material as cobalt ones and that is because they’re not as hard.

However, they are more resistant to breaking and can usually handle more types of material without damage.


Both Black Oxide and Cobalt bits are made of high-speed steel (HSS). Of course, that makes them extremely hard but that doesn’t mean that they won’t break or chip when used incorrectly.

That said, cobalt drill bits are more resistant to wear and tear because they have a higher carbon content than Black Oxide bits.

They are also crafted with high precision and sharpened to within 0.0005 inches, making them more efficient and suitable for complex projects.

Cobalt Drill Bit Set


Cobalt bits tend to cost more than those made from Black Oxide simply because they are more superior in quality.

Nonetheless, if your project is a small scale one, or if you don’t plan on drilling anything harder than plastic or softwood, then you might want to consider saving your coins by purchasing Black Oxide drill bits instead.

Manufacturing Process

Perhaps you don’t know this but black oxide drill bits are now the most common type of drill bits used. This is because they are cheap yet durable.

The black color is applied during the heat-treating process.

On the other hand, cobalt drill bits are stronger and more expensive than black oxide drill bits. This is because they are made with cobalt steel rather than low carbon steel.


With black oxide drill bits, you can expect chipping especially when too much pressure is applied. They will also break when overheated or overused.

Black oxide drill bits can be used to drill holes in most types of metal and wood, but they will become dull after a certain period of time.

On the other hand, cobalt drill bits can be used to drill holes in hard materials like masonry, glass and tile without getting dull.

Cobalt drill bits can also be used to cut through glass, tile and masonry without breaking or chipping as easily as black oxide drills.

Heat Resistance

If you’re building a new deck or outdoor structure, it’s not uncommon to come across black oxide and cobalt drill bits. Both are superior materials that can help make your project a success, but you need to keep in mind that each has its own application.

Black oxide is designed resist heat. This is the reason why many brake calipers are made of black oxide.

That also means that these drill bits can be used in high temperatures without overheating.

Cobalt is also resistant to heat, but it has a different composition to black oxide. Cobalt bits will still be able to withstand high temperatures, but they won’t wear down as fast as the black oxide ones will over time.

Final Thoughts

There is an assortment of drill bits in the market and as you can imagine, they are not the same. Black oxide drill bits are more popular because they are more pocket-friendly and widely available.

Cobalt drill bits are quite pricey but they do come with durability. Now, most manufacturers claim that cobalt is better than black oxide, but that’s not essentially true.

Ultimately, it boils down to what you’re cutting through and how deep you want to go. To determine which between cobalt and black oxide is better, you need to weight the benefits and drawbacks of both.