What Affects the Spring Rate?
There are 3 things that affect the spring rate:
- Diameter of the wire: Diameter of the wire itself affects the spring rate because when diameter of the wire increases it gets stronger, meaning a wire which is harder to compress. So, if we know that a wire becomes harder when its diameter increases, we can say that:
When wire diameter increases, spring rate increases.
- Diameter of the spring: That is in fact
the mean diameter of the spring, achieved by subtracting the diameter of the wire from diameter of the spring:
The overall outside diameter of the spring (mm) - diameter of the wire (mm)
When diameter of the spring increases, the spring rate decreases.
- Number of Active Coils (length/height of the spring): Determination of the number of active coils varies according to spring design. Count the total coils minus two for springs with both ends closed. Count the total coils minus one for springs with one end closed and one end open.
As the number of active coils decreases, the spring rate increases.
Normal Springs has a fixed spring rate.
Step Linear Springs are springs which have 2 different spring rates.
Progressive Springs have a variable spring rate.
