Active coils: Active coils refer to the coils in a helical spring that are free to deflect under load. These are the coils that contribute to the spring’s overall flexibility and provide the necessary spring action when subjected to a force. In other words, active coils are those that undergo deformation when the spring is compressed or extended. The number of active coils is calculated by subtracting the number of end coils from the total number of coils.
End coils: End coils may have a different shape or configuration and are often not free to deform. End coils are typically used for attachment purposes or to provide stability to the spring.
Total Coils: The total number of coils in a spring includes both active coils and the end coils.
Free angle: the angle between the arms of a torsion spring when the spring is in its unloaded or free state.
Inner diameter: The inner diameter of a spring, also known as the coil diameter or inside diameter, refers to the diameter of the central opening or void within the coiled structure of the spring. It is the distance across the centre of the spring, measured from one inner edge of the coil to the opposite inner edge.
Outer diameter: The outer diameter of a spring refers to the diameter measured from the outer edge of one coil to the opposite outer edge. It represents the overall width or thickness of the coiled structure of the spring.
Leg length: In spring design, the term leg length typically refers to the distance from the centre of the spring to one of its support points or ends.
Spring rate: In spring making, the spring rate refers to the amount of force required to compress or extend a spring by a certain amount. It is a measure of the stiffness of the spring. A lower spring rate means that less force is required to compress the spring, making it softer. A higher spring rate means that the spring is stiffer and requires more force to compress or extend it.
Torque: In spring design, torque refers to the rotational force or moment applied to a spring, especially in the context of torsion springs. Torsion springs are helical springs designed to generate torque when twisted around their axis. The torque is a measure of the spring’s ability to resist or produce rotational motion.