As a standard and widely available option, the twist drill bit is the superior choice for variable drilling tasks. The twisted design can remove debris from the hole effectively and reduce friction, which makes it widely used in multiple applications.
Its ability to efficiently create holes in various materials makes the twist drill bit useful on multiple materials, like wood, plastic, and even metal. All these make it an ideal choice for both professionals and hobbyists.
But what is a twist drill bit? What is it used for? Or how to choose a compatible twist drill bit for your projects? These are all we discuss in this blog. Now, follow the guide to explore the secret of the twist drill bit.
What is a Twist Drill Bit?
A twist drill bit, or a fluted bit, is the most common type of drill bit and is suitable for general-purpose drilling on variable materials, like wood, plastic, metal, ceramic, and masonry.
It consists of 7 parts, including a point, flutes, cutting edges, shank, helix angle, web, and chisel edge. And we will introduce you to them one by one in the following section.
Components of a Twist Drill Bit
- Point (tip): It is designed to center the bit and reduce sliding on the material. The angle of the point is crucial, which is measured between two major cutting edges, typically around 118 degrees and 135 degrees. For drilling softer materials, 118 degrees is better; while for drilling harder materials, 135 degrees is better.
- Flutes: The flutes are the spiral-shaped grooves that run along the drill bit’s length. Flutes have multiple functions, such as facilitating chip removal, providing a path for cooling the bit during operation, and guiding the cutting edges.
- Cutting edges: The sharp edges along the point's sides where the actual drilling action occurs. Each cutting edge is responsible for cutting into the material as the bit rotates.
- Shank: The end of the drill bit opposite the point. It is the part inserted into the chuck of a drill or drilling device. Shanks can be straight, which fits standard drill chucks, or tapered, which are used for heavy-duty drilling applications, depending on the drill bit's size and application.
- Helix angle (spiral angle): This refers to the angle formed by the flutes and is a critical factor in drill design, affecting chip removal. The range is from 12 to 45 degrees. With higher angles, it is suitable for softer materials, and with lower angles, it is more suited for tougher materials.
- Web: The central portion that connects the two flutes is called the web. The web's thickness influences the drill bit's rigidity and strength. A thicker web provides more strength but can make the bit harder to sharpen.
- Chisel edge: The edge formed by the intersection of the point and the flute has no cutting effect. Nonetheless, because it joins the two primary cutting edges, it’s necessary for its construction. It helps guide the drill bit into the material and contributes to the cutting action.
Note: These drill bits may need to drill a starter hole. With the correct feed rate, it effectively prevents drill binding and premature wear.
Types of Twist Drill Bits
Twist drill bits come in a variety of material compositions and coatings, including high-speed steel (HSS), cobalt steel, and carbide, each designed to optimize performance for specific applications.
High-Speed Steel (HSS)
HSS is the most commonly used material for twist drill bits due to its affordability and versatility. HSS bits are known for their durability, improved wear resistance, and ability to maintain hardness at high temperatures, making them suitable for a wide range of general-purpose drilling applications, including wood, plastic, and soft metals like aluminum and brass.
Cobalt Steel
Cobalt drill bits are made from an alloy that typically includes around 5-8% cobalt, enhancing the bit's performance. The addition of cobalt increases the bit's heat resistance and hardness to the steel, allowing it to withstand very high drilling temperatures and resist wear. They are ideal for drilling through very hard, abrasive materials such as treated stainless steel, titanium, and cast iron.
Carbon
Carbon drill bits are composed of tungsten carbide, a material known for its extreme hardness and heat resistance. These bits maintain their sharpness and structural integrity under intense heat and wear conditions, although they can be brittle and prone to chipping if misused.
They are suitable for industrial applications involving hard and abrasive materials like ceramics, hardened steel, and composites. They are also commonly used in CNC machining and other precision environments.
Although Carbon drill bits are the most expensive option, they provide the highest performance and lifespan, making them the preferred choice for industrial and heavy-duty applications.
Coatings
In addition to the material composition, twist drill bits can also be coated with various materials to enhance their durability and performance.
Titanium Nitride (TiN)
TiN is a more expensive coating applied to HSS bits, giving them a distinctive gold color. This coating significantly increases surface hardness, enhances corrosion resistance, and reduces friction between the bit and the workpiece.
TiN-coated bits can last up to six times longer than standard HSS bits, commonly used for drilling metals, including stainless steel, cast iron, aluminum, magnesium, etc.
Titanium Aluminum Nitride (TiAlN)
TiAlN is a more advanced coating that offers better wear resistance and heat resistance compared to TiN. It provides superior heat resistance and hardness, allowing the bit to withstand higher cutting speeds and temperatures without losing its sharpness.
TiAlN-coated drill bits are suitable for high-speed drilling in harder and abrasive materials such as hardened steels and ceramics, and production environments where long tool life and high efficiency are critical.
Black Oxide
Black oxide is a heat treatment applied to HSS bits, resulting in a black finish. This treatment reduces friction between the bit and the workpiece, resulting in a 50% longer service life compared to standard HSS bits.
This coating also provides mild corrosion resistance and is an affordable option with increased lifespan and reduced friction, suitable for a wide range of general-purpose drilling applications.
How to Select the Right Twist Drill Bit for Your Needs?
Some factors need to be considered when choosing a compatible twist drill bit, like the desired hole size, the material, the types of drilling machines, and the requirements of the project.
- For home projects or light industrial, HSS drill bits are an affordable option.
- For drilling harder materials, cobalt drill bits are better due to their heat resistance and hardness.
- For drilling extremely hard or abrasive materials, carbide drill bits are the best choice due to their durability and reduced downtime.
- For high-speed drilling and demanding tasks, TiN-coated bits and TiAIN-coated bits are better due to their high surface hardness and reduced friction.
- For general-purpose drilling, black oxide-coated bits are an affordable option due to a longer lifespan and reduced friction.
FindBuyTool offers industrial-grade twist drill bits ideal for drilling wood, metal, plastics, and aluminum. We have two affordable twist drill bits: HSS twist drill bits and Cobalt twist drill bits.
The HSS twist drill bits provide a point angle of 118 degrees. And the cobalt twist drill bits are made of HSS-CO 5% (M35) for durability and long-lasting high performance.
Our drill bits are designed for heavy-duty work, and each of them meets exacting tolerances and can perfectly drill 1-13 mm-sized holes in all materials, including but not limited to wood, stainless steel, and masonry.
If you still have any questions about the twist drill bit or our blog, please leave a comment with an available email, and we will reply to you via it ASAP!
Read More:
Master Types of Drill Bits and Their Uses in 5 Minutes
Brad Point Drill Bit vs Twist Drill Bit: What’s the Difference?
FAQ about Twist Drill Bit
#1 What is a twist drill bit used for?
The twist drill bit is used for drilling holes in wood, plastic, metal, ceramic, and masonry.
#2 What is the difference between a twist drill bit and a brad point drill bit?
Brad point drill bits are specialized in precision in wood. It has a sharp center point, which helps position and stabilize the bit accurately. And the cutting edges can reduce tear-out. Twist drill bits are more widely used but lack precision.
