How Do Drill Bits Work

Published On: December 16, 20210 Comments on How Do Drill Bits WorkLast Updated: February 3, 20245.6 min read

The drill bit is used for drilling holes in metal, wood, concrete, aluminum, and other materials. Before we get into how the drill bit works, let’s go over some of the drill bit’s key components. 

How Do Drill Bits Work

  • The shank, body, and point are the main parts of a drill bit.
  • The drill bit’s point is shaped like a cone. 
  • The intersection of the bit’s helix forms a pair of cutting edges known as cutting lips.  
  • The cut chisel edge is  between the cutting lips.  

The fundamentals

Drill bits are essential components of a power drill or drill press since they are responsible for creating the hole. Drill bits come in a variety of sizes and forms and for a variety of applications. For example, there are bits for drilling into  wood as well as brick and concrete. The drill bit’s cutting edges do the actual cutting. When you drive a drill bit into a metal sheet, the cutting edge rotates and is pressed into the metal along the shear plane line. During the drilling operation, the forces along the shear plane exceed the forces holding the metal together, causing the metal to break and creating a hole.

How Do Drill Bits Work - drill bits

What is the purpose of twisted grooves on drill bits?

All drill bits have flutes, which look like spiral grooves. Two flutes are the most common, but there are also drill bits with three or four flutes. Flutes do not cut, but they are an essential part of the drill bit. They allow the chips created during drilling to exit by spiraling upwards and outwards. The flutes help in the formation of the tip’s geometry and the passage of coolant and oil to the cutting tip. 

Why do drill bits spiral?

The flute’s spiral shape aids chip absorption and removal. The greater the width of the groove profile, the greater the chip absorption and removal. The rate of chip removal is controlled by the spiral or rate of twists in the drill bit. A rapid spiral or a high twist drill bit is utilized in high feed rate applications with moderate spindle speeds when a large number of chips must be removed. However, low spiral or low twist rate drill bits are used in cutting applications such as aluminum or copper.  Poor chip removal can result in increased heat development, which can lead to twist drill fracture.

Why do we do a pilot hole?

A pilot drill is used to start a hole before using a larger drill to make the desired size hole. The purpose is to guide a larger drill into the proper place and make drilling easier. Pilot holes can also be used to remove extra material before placing a screw or nail into wood, preventing it from cracking.

How Do Drill Bits Work - chisel edge

How Are Drill Bits Made

Drill bits of the finest quality and precision have been developed using modern production processes. Drill production has become easier and more efficient as a result of technological advancements and innovation. Different manufacturers use different procedures, but the following process is generally used to produce a drill bit.

  • Designing

Computer-aided design is the first step in ensuring quality and precision. The computer generates drawings that will be the basis of manufacturing designs and production.

  • Straightening and cutting

Harden steel blanks are used in addition to coil cut-off. The term “cut off” refers to the process of straightening and cutting raw material to length. The twist drill’s shape is created via copy turning. The blank is sometimes formed by friction welding sections of rods composed of HSS and tool steel.

  • Treatment with Heat

The blanks are constructed of high-performance, high-speed steel or are heated in a vacuum furnace to 1200 degrees Celsius. The vacuum shields the red hot steel from the destructive effects of oxygen. The vacuum furnace is flooded with nitrogen, and the steel is chilled at the end of the heating process.

  • Tempering

After chilling, the blanks are tempered at 550 degrees Celsius. Tempering reduces brittleness while increasing the hardness and toughness of steel.

  • Shaping

The first shape of the tool begins with a procedure known as centerless grinding. The hardened blanks are cylindrically ground to the necessary diameter during this procedure. The final features of the twist drill are increasingly taking shape.

  • Flutes are made.

The flutes are grounded into the tool’s body. Meanwhile, the body relief is increased, followed by the final grinding of the drill tip. Some of the drills have a black surface finish as a result of the following steam treatment. The twist drills are subjected to the environment of superheated steam and the tempering furnace for roughly 1 hour.

  • Coating Application

Different twist drills are also coated with titanium nitride, titanium carbon nitrate, and aluminum nitrate. The coating is applied in specially built vacuum chambers, allowing the coating ingredients to be evaporated onto the tool’s surface.

How Do Drill Bits Work - types of drill bits

How do I know which drill bit to use?

The drill bit to use will depend on the material you’re going to drill. A multi-purpose drill such as the twist drill is the most frequent and widely available. These are used for various routine tasks, but twist drills, but then also, wood, or plastic. Auger drill bits are similar to multi-purpose drill bits, but they only drill wood and have a more pronounced central point or spur. As a result, they make holes with exceptionally clean edges and are excellent for precision drilling. 

Spade Drill Bits are intended for drilling large holes in wood quickly. They come in various diameters and are perfect for drilling holes in wood posts for cables, wires, pipelines, and ropes. However, they produce splintering surrounding the hole’s entrance and exit. On the other hand, masonry bits are drill bits that can drill into concrete. They can also be used to drill through brick and stone. They include a deep spiral groove to help direct debris out of the hole while you drill.

How can you tell if a drill bit is for masonry?

The main visible distinction of masonry bits is that their tips are shaped like an arrowhead or have a gently sloping tip. They lack the blunt, slightly rounded tip found in general-purpose bits. Masonry bits are sometimes coated with carbide, which extends their sharpness.

How many different types of drill bits are there?

There are many types of drill bits. But the three most common are metal drill bits, wood drill bits, and masonry drill bits. Although, there are several other types under each category. For example, masonry bits can have percussion bits, rotary bits, and diamond bits. 

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