Difference between open and closed coil spring

The springs are classified as :

  1. Closely coiled spring
  2. Open coiled spring
Difference between them are as following below :

  • A helical spring is said to be closely coiled when the spring wire is coiled so close in open coiled spring wire is coiled in such a way, that there is large gap between adjacent coil.
  • In closely coiled spring helix angle is very small usually less than 10 degree while in open coiled spring helix angle is large about to more than 10 degree.
  • Closely coiled spring is also known as tension or extension spring while open coiled spring is known as compression spring.
  • In open coiled spring both torsional and bending stresses are significant because of large helix angle while in closely coiled spring only torsional stresses are predominant.
Applications of closely coiled spring :
  • Garage door assemblies
  • Vise-grip pilers
  • Carburetors 
Applications of open coiled spring :
  • Ball point pens
  • Pogo sticks
  • Valve assemblies in engines