What Are Drill Bits Made Of? Types And Comparison Of Drill Bits Materials

A drill bit is an essential tool in any toolbox used to create holes in objects by removing some material. They are made of different materials, including metal, cast iron, copper, aluminum, steel, brick, fiberglass, and vinyl flooring. Each drill type is suited for a particular application based on its material.

Whether you want to drill solid wood furniture, metals, or porcelain, there is always the right drill bit that suits your work. However, it is essential to understand the drill material and the object being worked on to get the perfect result. Here you will get to know drill types based on the material for wise decision-making. Keep reading!

What Are Drill Bits Made Of

Drill Bit Materials

Carbon Steel Drill Bits

Drill bits can be made of either high or low carbon steel, with each having its purpose. High carbon steel is a better material and can be used to drill through materials such as soft metals and hardwood.  They can keep their effectiveness and shape longer; thus require minimal maintenance. 

On the contrary, the soft carbon steel drill bits have poor tempers and thus can only be used for cutting some plastics and softwoods.  They can lose their shape quickly and might thus need regular sharpening to maintain its effectiveness. Nonetheless, soft carbon types are affordable, which is why people still prefer them for simple tasks. 

High-Speed Steel (HSS) Drill Bits

This is the most preferred option in the market compared to the carbon steel drill bits. The main advantages of the HSS drill bits are that it can withstand high temperatures, maintain its structural integrity, has superior wear resistance and hardness, and can still work well under normal temperature. 

You can use the HSS types to drill most metals and woods. HSS can also be coated with titanium nitride or other coatings to reduce friction due to high-speed turning to achieve better lubricity and improve its durability. 

Titanium Coated Drill Bits

Titanium is one of the premium coatings that improve the durability of the drill. It is a versatile material that is also used in popular medical and aerospace materials. The good thing is that titanium is corrosion-resistant, has a high heat limit, and a good fatigue limit.  If you often drill with large runs, then titanium coated drill bit is the best option; it can drill various steel and iron types and plastic and wood.  

However, there are various types of titanium coating; Titanium carbon nitrate (TiCN), Titanium Aluminum Nitride (TiAN), and Titanium Nitride (TiN), which differs in strength. Among the three, TiCN and TiAN are superior and considerably improve the lifespan of the drill bit. The only disadvantage of this drill bit coating is that it cannot be sharpened when it becomes blunt to prevent coating material from coming out. 

Zirconium Coated Drill Bit 

Metallic and steel drill beat can be coated with zirconium to improve their strength. Besides, the coating will reduce friction that, in turn, improves precision drilling.  

Cobalt Coated Drill Bit 

Cobalt coated drill bits are best for cutting difficult materials such as stainless steel. It can withstand extreme temperatures compared to HSS while retaining its hardness for comfortable drilling. Nonetheless, care should be taken when using cobalt coated drill bits as it is too brittle. 

Carbide –Tipped Coated 

Carbide coated drill bits are the best when it comes to maintaining their edge longer. They dissipate heat easily and are hard, thus good for drilling materials such as nonferrous heavy metals and fiberglass reinforced plastics.  However, it can break if proper care is not taken since it is very brittle, just like cobalt-coated ones. 

Diamond Drill Bits

These drill bits are the hardest and suitable for drilling the toughest materials, such as ceramic and glass. Diamond drill bits are also durable though they can cost you a lot more compared to others. The only drawback is that these drill types can react negatively with ferrous materials such as hot steel. 

Comparison Of Drill Bits Materials: What Is The Best Material For Drill Bits?

The material is one of the essential considerations when buying a drill bit. It will not only affect its price but service life and properties as well. Now, you might be wondering then: what is the best material for drill bits? Is it steel, titanium, or metal? Below we compare some to help you make an informed decision. 

Cobalt VS. HSS 

Properties: Cobalt is the strongest with high wear resistance between the two. However, it’s very brittle compared to HSS. 

Application: HSS is best for drilling mild steel, wood, and plastic. On the other hand, cobalt does all the work that HSS do and drill other tough materials such as stainless steel

Price: Generally, HSS is less expensive compared to cobalt.

Cobalt VS. Titanium

Properties: cobalt drill bits are made of high-speed steel with cobalt coating, while titanium types are made of either HSS or carbon steel but with TiCN, TiAN, or TiN coating. However, titanium drill bits are the strongest and tend to last longer.

Application: since titanium-coated drill bits are sturdy, they are best for drillers who drill often. They can drill various steel, iron, wood, and plastic. The good thing about titanium is that they reduce the temperature when working in wood and plastic materials. Cobalt, on the other hand, is best for difficult metals such as hardened alloy steel. However, they are brittle, and this may not last you for a long time. 

Price: Titanium is expensive compared to cobalt coated types.

Cobalt VS. Carbide

Properties: carbide drill bits are extremely resistant to high heat compared to HSS and cobalt. 

Application: Cobalt types are best for drilling difficult metals such as hardened and stainless steel. Carbide coated drill bits, on the other hand, are best for drilling abrasive metals, cast iron, and nonferrous heavy metals.

Price: Carbide bits tend to be more expensive than cobalt types

Cutting speed: carbide has a higher cutting speed compared to cobalt coated drill bits. 

What Are The Hardest Drill Bits?

Carbide is the hardest drill bits of all types. However, it is very brittle and thus needs extra precaution when using it. Mostly, carbide types are used for production drilling where premium equipment and tool holder is used. It is not recommended for drill presses and hand drills as it can get easily damaged. Nonetheless, they are best for the most demanding materials such as nonferrous heavy metals and fiberglass reinforced plastics.

Classification Of Drill Bits

Drill bits are classified into five broad categories: Counterbore, twist drill, flat bottom boring, countersink, and specialty. 

Counterbore Drill Bits

Counterbore bits are made of HSS, carbon steel, or carbide tipped materials. They make a flat bottom blind hole that conceals the fastener head and prevent it from protruding above the material surface being worked on. The center hole has a small diameter, with some having spurs that prevent splintering and chipping on laminated or wood surfaces.

Twist Drill Bits

These bits are available in different materials such as HSS, carbon steel, carbide, and cobalt. Twist drill bits are the popular ones and have wide application as they are available in different sizes, materials, and varying tips.  Shorter ones tend to be the strongest, though they may not be suitable if you want to drill deeper.

Flat Bottom Boring Drill Bits

These drills are also available in different materials such as HSS, carbon steel, and carbide. It is designed like the counterbores but without a center drill. As the name suggests, flat bottom boring bits are suitable for cutting flat bottom blind holes and drilling wide thru-hole. These types of holes are used for wiring holes, door knobs, and locks. 

Countersink Drill Bits

These are used for countersinking existing holes to create a tapered surface hole with a center hole that is small to penetrate through the material being worked on. As a result, the tapered head fastener sits at a level to the surface of the material. Countersink drill features two or more flat blades that emanate from the center of the drill and extends to its outer edge.

Specialty Drill Bits

Other drill bits that do not fall under the above categories are known as specialty drill bits. These may include plug cutters, glass and tile drills, masonry drills, augers, and annular cutters. 

Specialty Drill BitUse 
Plug cuttersCut around plugs from lumber used to seal counterbore  
Glass and tile drill bitUsed to create holes in tiles, non-tampered and other similar materials 
Masonry drillsUse to create holes in bricks and concrete, among others. 
Augers Used to drill large holes that penetrated deeply into the material being worked on 
Annular cuttersUses special machine to create large thru-holes in metals

Final Word

Material is an essential aspect to consider when buying a drill bit as it affects its application, durability, and cost. Luckily, you will always find one that suits your need, and there is no justification for missing one in your toolbox. 

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