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Types of Bimetallic Strip and its Construction

Types of Bimetallic Strip and its Construction

Definition of Bimetallic Strip

Bimetallic strip works on the principle of thermal expansion in which the change in volume of metal with the change in temperature. The bimetallic strip works on two basic fundamentals of metals that the metals expand or contract based on variation in temperature. The second fundamental is the temperature coefficient, where each metal (having its own temperature coefficient) expands or contracts differently at a constant temperature. It is regularly observed in applications like heaters, iron boxes, kettles, etc. A bimetallic strip converts thermal energy into mechanical displacement.

Properties of Bimetallic Strip

Some of the main properties of the bimetallic strip are:

  • Ductility
  • Coefficient of expansion
  • Elastic limit on cooling
  • Elasticity modulus
  • Electrical conductivity
  • Metallurgical Ability.
  • Construction of Bimetallic Strip

Construction of Bimetallic Strip

A bimetallic strip is constructed by bonding two different thin strips of metals, usually steel , aluminium, or copper where one end of these metals are fixed by welding them and the other end is left free. When temperature is applied to these metals, then they will start to change their physical state either by expanding or by deforming.

Advantages of the bimetallic strip

  • Simple in utilization
  • No external power source is required
  • Gives accuracy between ± 2 to 5 %
  • Robust construction and Cost is low
  • It is easy to use and it can be used up to 500 °C.

Applications of Bimetallic Strip

The following are the applications of the bimetallic strip and finds applications in manufacturing of important products like clocks, thermistor, iron box, heat engine, heaters, etc.

Frequently Asked Questions (FAQs)

1. What devices use a bimetallic strip?

Ans: A bimetallic strip is used in devices like a fire alarm, fans, etc.

2. What happens when a bimetallic strip is heated?

Ans. When a bimetallic strip is heated, the metals either expand or deform based on their thermal coefficient properties.

3. Is bimetallic strip used in fans?

Ans. Yes, they are used in fans to convert temperature into mechanical displacement.

4. Why do bimetallic strips bend?

Ans. Bimetallic strips bend due to the metal thermal expansion property.

5. Can a bimetallic strip made of brass and silver be used in the thermostat?

Ans. No, a bimetallic strip made of brass and silver cannot be used in the thermostat. Since they have a negligible difference in their thermal expansion property.

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