Black Oxide Vs Cobalt Drill Bits – Which One is the Best?

When you go for buying a drill bit, you can see, many types of drill bits are available in the market. Among them, black oxide and cobalt drill bits are common bits. These bits are made with different materials. Hence both have different properties. So let’s see, in detail about black oxide drill bits Vs cobalt drill bits.

Black oxide drill bits are made with a magnetite (Fe3O4) layer coated on the HSS drill bits and Cobalt bits are made from 5-8% of Cobalt alloy with HSS drill bits. HSS drill bits can be used for metal, wood, plastic, and Cobalt bits are for the Hardest material. Cobalt is more durable and expensive than black oxide drill bits.

There are more properties and usage. When you use them for your task, you should know them well. So I am going to explain and compare them step by step below. So please keep reading below.

Black Oxide Vs Cobalt Drill Bit – Comparison

FeaturesBlack Oxide Drill BitsCobalt Drill Bits
HardnessHarder enough but less than othersHardest
Material DrilledMetal, wood, plasticHard metal
Durability50% more durability than HSSHighest
Rust resistanceHasHas
Re-sharpenableyesyes
PriceCheapestVery expensive
The differences and similarities between black oxide drill bits and cobalt drill bits.

HSS Drill Bits Have Improved as Black Oxide and Cobalt Drill Bits

High-Speed Steel (HSS) bits are the basic drill bit type of the other drill bits. They consist of carbon steel alloyed with tungsten or molybdenum. Variations helped to improve the effectiveness of the drill bit. Variations are coatings and structures. 

Black oxide drill bit and Cobalt drill bit are the two types of improvements of HSS drill bits. There has another type of titanium drill bit also but this article gives you important details about black oxide drill bits and cobalt drill bits.

How to Identify the Black Oxide Drill Bits?

Black oxide drill bits are black in color and their price is in the middle range considering other drill bits in the market.

How to Identify the Cobalt Drill Bits?

Cobalt drill bits are dark gold in color and it is not a bright gold color. Bright and shiny gold color drill bits are coated with titanium. Cobalt drill bits price is higher in the market.

Cobalt Drill Bit Vs Black Oxide Drill Bit

Read More About – How to Identify the Drill Bits? – Expert Guide!

Black Oxide Drill Bits

Drill bits that are made with black oxide coating can identify as “black oxide drill bits. Those bits are made with a magnetite (Fe3O4) layer coated on the HSS drill bits. The black oxide layer is more important for thermal resistance, heat resistance, and corrosion resistance.

When we use black oxide as a drill bit all these are important. Additionally, it can increase the life of high-speed steel. When thinking about drilling material, black oxide drill bits are the most versatile. Those are suitable for work on;

  1. Copper,
  2. Aluminum,
  3. Brass,  
  4. Plastic,
  5. Oak,
  6. Maple,
  7. MDF,
  8. Pine,
  9. PVC,
  10. Polycarbonate,
  11. Acrylic,
  12. ABS,
  13. Nylon and composite materials.

Read More About – 26 Types Drill Bits for – Metal | Wood | Stone | Concrete

Coating Process of Black Oxide Drill Bits

Under the black oxide coating processes, three types of coating processes can be identified. Those are:

  1. Heat process
  2. Mid-temperature process
  3. Cold process.

Those three processes are based on temperature.

HSS heats to 950 degrees of Fahrenheit (oF). This process will help to resist rust and corrosion of the drills because of the friction between the bit and the workpiece will reduce. Therefore; the drilling efficiency and durability of the drill improved.

As well as, friction while drilling will decrease and it helps speed up the drilling process to a considerable extent. Although black oxide drill bits can be produced by using a cold coating process.

This is a helpful guide to learn about Drill Bit Material, Coating and Usage in Depth.

Middle temperature is also used to make black oxide drill bits. Under the cold nature (68–86 °F) true oxide does not produce. It’s like a soft coating. Anybody can scratch the drill bit by using an even coin.

Usage and Durability of Black oxide Drill Bit

Black oxide drill bits are the best general-purpose drill bits. Those are being cheapest and serve all kinds of purposes. Therefore, black oxide drill bits can be introduced easily for the freshener of the industry. It will more efficient step.

Let’s talk about the limitations of the black oxide drill bits, revolutions per minute (RPM), durability, and sharpen time can be identified as limitations. As previously mentioned the black oxide coating helps to increase the speed of drilling and durability of the drill bit.

Black oxide drill bits are fifteen percent durable more than HSS drill bits because those are re-sharpenable drill types. When thinking about affordability, black oxide drill bits are very cheapest than other drill bits.

When your drill bit is blunt you should properly sharpen the drill bit. This is how I do it.

Cobalt Drill Bits (HSCo)

Titanium Vs Cobalt Drill Bit

Cobalt drill bits are not made from pure cobalt. Cobalt drill bits are made from 5-8% of Cobalt alloy with HSS drill bits. This composition helps to give high resistance from rusting. Based on the percentage of the Co in the drill bit, can be identified the different Cobalt drill bits.

Types of Cobalt Drill Bits

Among those types of drills, M35 and M42 are the most common Cobalt drill bits. M35 Cobalt drill bits contain approximately 5% cobalt alloy and M42 cobalt drill bits contain approximately 8% cobalt alloy

Physical Properties of the Cobalt Drill Bits

The melting point of the Cobalt is 1495°C and the boiling point is 2927°C. Which makes it perfect for use at high temperatures. The corrosion is cannot identify in the cobalt drill bits. The cobalt drill bit is designed to drill fast. Therefore, this type of drill is suitable for the hardest drilling purposes. Such as cast iron, titanium etc. Cobalt drill bits are exceptionally durable than black oxide drill bits. The toughness of the drill bits affected the durability.

Resharpness of the Cobalt Drill Bit

Cobalt drill bits also can be re-sharpened. Cobalt bits have a uniform concentration of cobalt in their composition. Uniform concentration means the coating process has unique patterns of cobalt moles because cobalt (Co) is the chemical mole in the D block of the periodic table.

Recoating process cannot rearrange this unique pattern very well. Therefore, cobalt drill bits cannot be re-coated but they can be sharpened to regain their edge. Cobalt drill bits are very expensive. Cobalt drill bits have a high resistance to heat therefore, those drill bits are suitable for rigid materials.

Cobalt Vs Black Oxide Drill Bit – Overview

When concerned about the differences and importance of these two drill bits, the black oxide drill bit is suitable and enough for daily drilling purposes.

Cobalt drill bits can use for professional and industrial valued construction purposes.

If you have to a long period of drilling work, unconditionally you have to use the cobalt drill bits because black drill bits tend to lose their edges very easily than cobalt drill bits when used for the hard material drilling process.

Drill bits can be re-sharpened by using a drill bit sharpener but a skilled person can use a grinding disc and re-sharper by hand.

Read More About – Choose the Right Drill Bit – Geometry | Coating | Material

The final conclusion is black oxide drill bits are most suitable for regular usage because;

  1. Reasonably priced,
  2. Durable ( non-corrosive and can be re-sharpened),
  3. 50% more durable than regular HSS drill bits,
  4. Can be used for various purposes,
  5. Making them the best all-purpose bits.

At first, you have to determine the metal or material type required to drill. Among both of those, cobalt drill bits are the most effective and best drill bit. Although you have to choose a good quality drill bit and use appropriate safety protection. 

If in doubt it is best to drill slowly and use a metal drilling lubricant for better drilling. Take suitable breaks to avoid the drill bit overheating.

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