What is a Screw

A screw is a simple machine consisting of a twisted inclined plane wrapped around a cylinder in ridges. It has a sharp tip and is mainly used for drilling into wood, plastic, stone, and metal. The ridges allow a screw to drill deep.

Parts of a Screw

A screw consists of two main parts – body and thread. The cylindrically shaped body is the main shaft of the screw. The inclined ridges on a screw are called threads. The distance between two threads remains constant and is the pitch of the screw. One end of the body forms the head, and the other is the tip.


How Does a Screw Work

The primary purpose of a screw is to drill into objects. It displays a circular motion, which then converts into a translational motion. Rotating a screw creates a torque that transforms into a linear force and moves the screw linearly along its axis from one position to another.

How Does a Screw Work

Mechanical Advantage of a Screw

The mechanical advantage of a screw is a measure of how much the applied force is multiplied to produce some valuable work. Mathematically, it is given by the ratio of the output force to input force.

Mechanical Advantage = Output force/ Input force

Since the applied force is multiplied, the output force is greater than the input force. Hence, the mechanical advantage is greater than one.

The mechanical advantage of a screw depends upon the pitch. A narrower pitch requires lesser effort to drive a screw than a wider pitch. However, the number of turns is higher.

Types of Screw

Although the primary function of a screw is to drill into a surface, it can also serve other functions. A screw can be used to hold parts of machinery together. It is used in combination with a nut whose threads match that of the screw. The screw passes through a hole, and the nut rotates and moves over it to tighten. This type of screw is known as a bolt and does not have a tip.

Another purpose of a screw is to drill holes on a surface using an electric device. However, unlike a conventional screw, it does not permanently stay on the surface. It scoops out a piece of material from the surface. This type of screw is known as a drill bit and has a pointed end.

Examples of Screw

  • Jar lid
  • Bottle cap
  • Faucet
  • Car jack
  • Gas tank cap
  • Light bulb
  • Corkscrew
Screw Examples

Applications and Uses of a Screw

  • Drill into wood, plastic, stone, and metal using a drill bit
  • Connect two or more parts of a machine, like a water pump, using nuts and bolts
  • For woodworking, especially joining furniture and cabinet parts using woodscrews
  • Open wine bottle using a corkscrew
  • Lift heavy objects using a car jack
  • Tighten things using a vice

Article was last reviewed on Tuesday, January 18, 2022

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