What is Drill Bit? – its Diagram, Types, and How it Works

Drilling bits or tools are required for drilling machines to make holes in materials. These tools are end-cutting tools designed for producing holes in a workpiece. The machine is said to be applied in different fields and to various materials such as wood, metal, and rock.

Drilling tools vary widely, as they are designed to accommodate the properties of the workpiece and the radius and depth of the desired hole.

This shows that different construction companies use drilling machines. They are made of various types, suitable for specific operations. Drilling tools are used to achieve different operations, and there are other types of drill bits for different holes. In this reading, we’ll explore what a drill bit is, its parts and diagram, types, construction, materials, and coating.

Let’s get started!

What is a Drill Bit?

Drill bits are essential tools for drilling holes in common materials such as wood, metal, plastic, ceramic tile, porcelain, and concrete. These tools come in various sizes and shapes, with each having a unique tip but having similar parts. They are designed for various materials, including steel, aluminum, copper, cast iron, sheet metal, fiberglass, brick, and vinyl flooring.

Drill bits are sized for their diameter and are constructed in various styles to help with specific tasks. Common materials include sheet metal, ceramic tile, porcelain, and concrete. Each drill bit has its own unique tip, but they share the same parts with little or no difference. The various components of a drill bit are body, point, shank, tang, flutes, land, body clearance, neck, and web.

Related: What is Drilling Machine? its Diagram, Types and Specifications

Drill Bit Construction, Materials and Coating

Power drills consist of two key components: the shank and the chuck. The shank is the end of the drill bit that fits into the drill and is secured by the chuck. Round shanks center the bit more accurately, while hex shanks have flat surfaces for a more secure grip.

SDS shanks are used for concrete drills and demolition bits, specifically with SDS-Plus and SDS-Max rotary hammer drills. The chuck is the part of the drill that attaches the drill bit, typically 3/8-inch or 1/2-inch in most home-use power drills. Larger chucks are typically used on heavy-duty and industrial power drills and drill presses.

Drill bits are a crucial tool in various industries, primarily made from high-speed steel (HSS) materials. These bits are suitable for drilling wood, light metals, fiberglass, and PVC. Black oxide-coated drill bits are durable and resistant to rust, making them ideal for hardwood, softwood, PVC, fiberglass, and steel.

Titanium-coated drill bits have reduced friction, require less effort, and last longer than black oxide-coated bits. Cobalt drill bits are ideal for drilling hard metal and steel, as they dissipate heat quickly and are highly resistant to abrasions. Carbide-tipped drill bits are used for concrete, tile, and masonry, while bi-metal drill bits are suitable for light metal, wood, and PVC.

Diamond drill bits are ideal for cutting into glass, sea glass, fused glass, rocks, and minerals. Alloy steel drill bits are commonly used in machine shops for cutting sheet metal of varying thicknesses, making them ideal for working exclusively with thin materials.

Coating 

Drill bits are coated with various materials, including black oxide, bronze oxide, and titanium nitride. Black oxide is the most economical coating, providing corrosion protection, increased tempering, and stress relieving properties. It is suitable for drilling iron and steel but not aluminum, magnesium, or similar materials.

Bronze oxide is used to visually identify cobalt steel or better grades of high-speed steel. Tin oxide, a more expensive coating, increases the hardness of the bit and provides a thermal barrier, increasing production rates and tool life in harder materials. Tin-coated bits are suitable for drilling iron, steel, aluminum, magnesium, and other materials.

Diagram 

Drill bit diagram

Names of 20 Kinds of Drill Bits

below are the names of different kinds of drill bits.

  1. Twist Drill Bit
  2. Brad Point Drill Bit
  3. Masonry Drill Bit
  4. Rivet Drill Bit
  5. Spade Drill Bit
  6. Installer Drill Bit
  7. Step Drill Bit
  8. Auger Drill Bit
  9. Self-Feed Drill Bit
  10. Forstner Drill Bit
  11. Hole Saw Drill Bit
  12. Countersink Drill Bit
  13. Plug Cutter
  14. Tile drill bits
  15. Adjustable Wood Drill bits
  16. Annular Cutter
  17. Bits for Metal
  18. Glass and Tile Drill bits
  19. Hammer Drill bits
  20. Bullet Point Drill bits

Types of Drill Bits 

The various drilling tools are flat or spade drills, straight-fluted drills tools, twist drills tools, taper shank core drills, oil tube drills, and center drills.

Twist Drill Tools

These drilling tools are the most common and are frequently used today. They are created using steel that was twisted and then honing the surface. The modern ones are made by machining two spiral flutes that run longitudinally around the body of the drill.

Parallel shank, parallel stub shank, parallel long shank, and taper shank are the four classification of a twist drill.

Flat or Spade Drill

A flat or spade drill is often put to use when a twist drill is not available. It is a forged circular tool steel with a cutting edge that ranges from 90 to 120 degrees with a relief at the front ranging from 3 to 8 degrees.

Straight Fluted Drill

The straight fluted drilling tool is often used when  drilling brass as it drills perfectly. It is used because it does not advance more quickly than the recommended feed like that of twist drill.

The drilling tool have flute or groove that are perpendicular to the drill axis and it is often used to drill softer material like copper and brass.

Taper Shank Core Drill

The drilling tools are designed to enlarge existing holes, that is punched, drilled, or cored. Taper shank core drill cannot create hole on solid substance due to the cutting edge that are machined at the center of the drill.

The metal or material is removed with the chamfered edge at the tip of each flute. These drill tools produce better finished holes than that of two-fluted drills. They are sometimes used to create a hole that is half the needed size with three or four fluted drill to complete the drills.

Oil Tube Drill

The oil tube drill is the process where earth drilling machine are used to bored oil tubes from the earth surface to form an oil well. The drilling tools are only used for the purpose.

Centre Drill

The center drill are used to drill center holes into the end of a workpiece. It is a twist drills with a striaght shank and two flutes are used. They drill the holes in precise dimensions.

Titanium Nitride Drill Bits

These kinds of drill bits are coated with titanium nitride. They are hard, fast, and are suitable for drilling soft and hard materials. They are suitable in wide industrial applications due to their properties. However, the cutting edge cannot be restored when it wear off, unless the coating is reapplied.

Titanium Carbonitride Drill Bits

The types is similar to that of nitride drill bit, but they are slippery with a characteristic of blue or purple color. Although they have superior hardness, which is why they specialize for drilling hard materials.

Titanium Aluminum Nitride Drill Bits

These kinds of drill bits are suitable for drilling stainless steel, steel, and materials of high temperature due to their high stability.

Black Oxide Drill Bits

The black oxide drill bits make use of inexpensive coating on high-speed steel, making them heat-resistance, fractionless, rust, and corrosion-resistan. They are suitable for drilling PVC, steel, maple, nylon, etc. and they are known are the best general-purpose drill bits.

Diamond Drill Bits

Diamond drill bits are the hardest kinds of drilling tools becuase they are coated in diamonds. They are suitable for drilling hard material such as metals or rock. Due to their high accuracy, they are suitable for material such as glass, sea glass, etc.

Step Drill Bit

These kinds of drill bits are custom made, having a conical shape and a running flute that can be straight or angled. This flute help remove the chips from the drilling surfaces. Step drill bits are suitable for drilling soft materials like aluminum and they are vary expensive because they are custom made.

Unibits

The unitbits are similar to step drill bit but have a straight running flute. They are used in hole enlarging and the flute help remove the chips during drilling. They are often used in sheet metal fabrication and drilling soft materials like plywood.

Hole Saw Drill Bit

These kinds of drill bits with short open cylinders with saw teeth on the edge. They are used in drilling through thin materials such as wood and sheet metals.

How to Choose a Drill Bit

To choose a basic drill bit, start by learning how to use a drill. The drill bit you use will depend on the task at hand and should be kept in your toolbox for various projects. A twist drill bit is needed for drilling holes, while screwdriver bits are for driving screws in with a drill.

Choose a bit that matches your project and drill a slightly smaller hole than the screw to ensure a firmly bite into the material. Phillips and flat head options are available for drill bits, and it doesn’t have to be an exact match to the screw. As long as the bit fits into the slots on the screw, it works.

Drill Bit Maintenance 

Drill bit maintenance is crucial for extending the life of your drill bits and ensuring safety. They are cutting tools, and dull or damaged drill bits can lead to increased work time, effort, and damage to materials. A sharpening tool can be a good investment to keep your drill bits in top shape.

Most drill bit sets come in a case with space to hold each bit in place, providing organization and easy access to the right bit for your project. If your set doesn’t come with a case or you’ve been buying individual drill bits, add a storage box with dividers to your toolset.

Tips for proper drill and drill bit maintenance include letting the drill bit cool off after finishing your project, wiping the drill and bit with a clean, dry cloth, brushing off any debris with a clean, dry toothbrush, applying machine oil lightly with a paper towel or microfiber cloth, letting it sit for a few minutes, and wiping up any excess oil with a new paper towel.

Inspect drill bits for any extensive damage and remove damaged ones from the set to be replaced. Place drill bits back into their case and store in a cool, dry place.

Related: What is Drilling? its Diagram, Operations, & How it Works

How to Change a Drill Bit?

To change a drill bit, follow these steps:

1. Disconnect the drill from the power source, either by removing the battery or unplugging it.
2. Open the chuck, which will be a circular piece with the bit in the middle. Rotate it until you see the chuck open. If you need a key, use the chuck key that came with the drill to open it.
3. Pull out the bit if it’s stuck. Put the old bit in a case or off to the side.
4. Insert the new bit into the chuck as far as it can go, ensuring it’s centered and not angled. Twist the chuck tightly around the drill bit.
5. Ensure your drill bit is snugly held.

How to Use a Drill?

To use a drill, figure out where you need screws, finish all measurements, and ensure any straight lines are level. Mark each hole with a pencil using a tiny X or make a dot. Always wear protective glasses or goggles when using power tools and secure loose clothing and hair before working.

To drill a hole, power up the drill, adjust the torque to suit the material you’re drilling, find the Xs or dots to mark where to drill, get at the correct level to drill the hole, stabilize the drill vertically, and gently pull the trigger.

For inserting a screw into a pilot hole, power up the drill, adjust the torque, fit the screw into the slot on the drill bit, line up the screw with the hole, ensure the drill is vertical, and press gently into the screw to keep it in place.

If you’re concerned about over-screwing, stop before the screw is completely inserted and finish with a screwdriver.

Drilling is a cutting process that uses a drill bit to cut a hole of circular cross-section in solid materials. There are 20 types of drill bits, and choosing the right one depends on your specific needs and requirements.

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