Question: What is spring index of helical spring? Discuss the significance of it in the design of it.
0

Subject :- Machine Design -I

Topic :- Spring

Difficulty :- high

md1(66) • 2.6k views
ADD COMMENTlink
modified 17 months ago  • written 19 months ago by gravatar for kiran.9870 kiran.987010
0

Spring index: It is defined as the ratio of mean coil diameter to wire diameter.

Let

    d = wire diameter of spring.

   Dc = inside or core diameter of spring coil.

   Do = outside diameter of spring coil.  

    D = mean coil diameter.

Mean coil dia

Dimensions of Spring

Significance of spring index:

  1. The spring index indicates the relative sharpness of the curvature of the coil.
  2. A low spring index means high sharpness of curvature.
  3. When the spring index is low (C < 3), the actual stresses in the wire are excessive due to curvature effect. Such a spring is difficult to manufacture and special care is required in coiling to avoid cracking.
  4. When the spring index is high (C > 15), it results in large variation in the coil diameter. Such a spring is prone to buckling.
  5. A spring index from 4 to 12 is considered best from manufacturing considerations. Therefore, in practical applications, the spring index usually varies from 4 to 12.
  6. A spring index in the range of 6 to 9 is still preferred particularly for close tolerance springs and those subjected to cyclic loading.
ADD COMMENTlink
written 17 months ago by gravatar for kiran.9870 kiran.987010
Please log in to add an answer.