Drill Bit Material, Coating and Usage – In Depth Guide!

Drill bits are made with different materials. Among them, steel, HSS, cobalt, carbide, and diamond drill bits are the most used drill bits for any material. Materials have different hardness and strengths. According to this drill bits have been designed to gain the most efficient cutting process.

Normally, each material can line up according to the Rockwell C hardness values. We are not able to drill higher hardness material with lower hardness drill bit material. Due to this reason, drill bits have been manufactured considering each material’s hardness.

So let’s see what the drill bit material, coating, and usage of steel, HSS, cobalt, carbide, and diamond drill bits are?

Drill Bit Coating

Drill bits are coated in order to increase friction resistance, heat transferring, and durability. Mostly HSS drill bits are coated with different kinds of materials. When a drill bit is coated, its color has changed. So let’s see what are the coatings and how are they useful?.

Black oxide

  • Reduce Friction in the cut
  • Reduce heat reduction
  • Improve the flow of material

TiN(Titanium Nitride)

  • Increase higher RPM using this coating
  • Better tool lifespan
  • Add resistance
  • Reduce friction

TiCN (Titanium Carbonitride)

  • Increase hardness
  • Add resistance

TiALN (Titanium Aluminium Nitride)

  • Increase hardness
  • Can be used in higher temperature
  • Lower thermal conductivity than TiN
Coated drill bits
Coated Drill Bits

Steel Drill Bits

Steel drill bits

Steel drill bits are significant for the softwood, plastic, fiber drilling process. Steel is not a hard material as it can be used for more hard and strong material. The melting point of the steel is (1375 – 1530°C (2500-2785°F)), and it will melt easily when it is used for drilling to the hard steel material.

Steel drill bits are really easy for sharpening as well as it can be blunt or damage the drill bit tip due to high temperature and resistance. Considering all the factors, steel drill bits are really useful for the general purpose.

HSS Drill Bits

HSS drill bits are made by mixing the carbon with the steel and chromium, vanadium, tungsten, and molybdenum with different proportions. HSS drill bits are really hard and tough than steel drill bits. HSS drill bits are black colored, and in order to increase the abrasion resistance, thermal resistance, some special coatings are applied, such as TiCN, TiN.

HSS drill bits are used to drill some hardwood and some soft steel such as aluminum, brass, etc. hardwoods. If you need to drill cast iron using the HSS drill bit, you can use it successfully. HSS can be easily sharpened, and it has good thermal and wear resistance.

Read More AboutWhat is HSS Drill Bit? – I Found These!

Cobalt Drill Bits

Cobalt drill bits are made by adding more percentages of cobalt to the HSS drill bit materials. When 5% cobalt is added to the mixture, it is 5% cobalt, and when 8% is added, it is super cobalt drill bits.

Cobalt drill bits can handle 1100 °F temperature and wear resistance. The more percentage of cobalt is more heat resistance. But a high percentage of cobalt is highly brittle. Hence limited cobalt is mixed with steel and carbon.

Cobalt drill bits can be resharpened without losing their strength. It has a relatively long life span and performs well in the cutting process.

Carbide Drill Bits

carbide drill bits
Carbide drill bits

Carbide drill bits are used to drill hard materials such as concrete, brick, stone, and many hard materials, Those are really resistant to the high thrust, heat resistance, and abrasion resistance. Normally carbide drill bits are used in hammer drills. The hammering mechanism is the most effective drilling mechanism into hard materials. Carbide drill bits are made with

  • Tungsten Carbide (WC) – Primary carbide component
  • Titanium Carbide (TiC) – Added to increase resistance to abrasive wear or cratering of chip forming surface
  • Tantalum Carbide (TaC) – Added to increase resistance to cutting edge deformation at higher temperatures during heavy cuts

When the carbide drill bit is less sharp, you should replace or resharpen the drill bit. Normally carbide drill bit is not able to sharpen easily with a regular grinder. You have to use a diamond grinder for the carbide bit sharpening.

Read More About – What is Carbide Drill Bit? – Complete Guide!

Drill Bits Coatings

(81 Rc)
(87 Rc)
(85 Rc)
(90 Rc)
Relative Toughness (1=Toughest)3124
Oxidation Temperature550ºC400ºC600ºC800ºC
Friction Coefficient0.650.450.50.45
Thickness2-4 microns2-4 microns2-4 microns2-4 microns
Surface Roughness (Ra mm)
Titanium coatings


Diamond Drill Bits

Diamond drill bits

Diamond Drill Bits are made with powder diamond and coated on steel as a layer. This is a process under 1.5 GPa pressure and 1250 ºC temperature.

Read More About – What is Diamond Drill Bit? – All You Should Know!

Sintered diamond drill bits or burrs – The diamond has been bonded to the matrix at a very high temperature; therefore, several layers of diamonds are dressed on the steel. This will increase the durability and more resistance of the drill bit.

Diamond drill bits are the harder drill bit in the world. So those are used to drill stones, glass, gems, tiles, and many more brittle materials. According to the diamond drill bit production, it is two types.

Electroplated or coated drill bits – Diomand is coated on the steel as a single layer. Then once the layer is wiped due to wear, you have to replace the tool. These are very economical and popular. Single Nickle is used as the bonded layer.

Diamond drill bits can use high thrust and high RPM in the drilling process.

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