1. Loads for torsion springs should be specified at a fixed angular position and not at a fixed deflection from the free position.
  2. Torque testing is not easily performed. While torque measurements can be taken, they can be inconsistent.
  3. Presently, there is no standard way to test loads for torsion springs.
  4. Diameter reduction and potential binding should always be considered.
  5. For applications that require minimum hysteresis (load loss) springs should be designed with space between adjacent coils to reduce frictional losses.
  6. 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.
  7. 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.
  8. 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.
  9. Direction of wind must always be specified for a torsion spring.

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