- Loads for torsion springs should be specified at a fixed angular position and not at a fixed deflection from the free position.
- Torque testing is not easily performed. While torque measurements can be taken, they can be inconsistent.
- Presently, there is no standard way to test loads for torsion springs.
- Diameter reduction and potential binding should always be considered.
- For applications that require minimum hysteresis (load loss) springs should be designed with space between adjacent coils to reduce frictional losses.
- A torsion spring should always be loaded in a direction that causes its body diameter to decrease. The residual forming stresses are favorable in this direction, but unfavorable when the spring is loaded in a direction that increases body diameter.
- Clearance must be maintained between the mandrel and spring at all times to prevent binding. The ideal mandrel size is equal to, or slightly less than, 90% of the I.D. when the spring is fully deflected (minimum diameter). Mandrels significantly smaller than 90% should be avoided to prevent buckling during large deflections.
- Most torsion springs are close wound. Hence, their body length will increase when a spring is deflected in the direction that will reduce the coil diameter. In tight housing situations, this increase should be considered.
- Direction of wind must always be specified for a torsion spring.