SPRING CALCULATIONS

How to Calculate the Spring Rate of a Coil Spring-

	(9909 x material dia.² x material dia.²)
Rate =	_____________________________
	(no. of active coils x mean dia.³)

• Mean dia. = I.D. + material dia.
• All measurements are in millimetres
• Result is in N/mm
• To convert answer to Kg/mm = N/mm x 0.10192

To Calculate Coil Spring Stress-

	(2.545 x rate(N/mm) x required travel x mean dia. x Wahl factor)
Stress =	______________divided by______________
	(material dia.³)

• Mean dia. = I.D. + material dia.
• C: (spring index) = mean dia. / material dia.
• Wahl factor = (C+0.2) / (C-1)
• All measurements are in millimetres
• Results is in N/mm² / MPa
• Stress not to exceed 827 N/mm² / MPa