Notes on springs

1. Common springs can be classified into three categories: tension coil springs, compression coil springs, and torsion coil springs.
Among them, tension and compression springs are mostly mass-produced, with complex specifications but suitable for application with slight modifications. If a small amount is needed and the spring characteristics are not critical, they are easily available on the market but the unit price is higher.

The users of exclusive agency parts mostly order them from professional spring manufacturers; if they are unable to design by themselves, they can also ask the manufacturer to cooperate with the trial production at an additional fee.

In recent years, the industry has adopted CNC computer-controlled or mechanical spring machinery to automate and labor-saving production with relatively stable quality. Based on ISO and international requirements for quality gradually increasing, almost all spring manufacturers can submit report data for testing spring characteristics.

2. Special occasions can be classified into: stacked plate springs, torsion bars, scroll springs, thin plate springs, disc springs, wave springs, spring washers, buckles, ring springs and other special-shaped springs.

These springs are produced by hand or special machinery in order to meet the needs of different environments. They are all custom-made and the price depends on the quantity. The basic sample fee is indispensable. There are only a few user-defined specifications for such springs, which are beyond the scope of the following introduction.

3. Designation size of coil spring:

3-1. Wire diameter: The main characteristic of the coil spring lies in the wire diameter.

3-2. Outer diameter: It is more convenient to measure the outer diameter of the coil spring, and it is easy to identify the size.

3-3. Number of turns: the total number of turns, the number of effective turns, and the number of turns at the closed end; the coil spring can withstand the external reaction force, partly depending on the number of turns.

3-4. Pitch (lead): the distance between the head and tail of a coil spring wire on the axis.

Generally, only when making a compression spring will care about this value, and the user of the spring does not need to specify its distance.

3-5. Free length: the length value when no external force is applied to both ends of the tension and compression springs. Generally speaking, the free length has nothing to do with the function of the spring. Unless the closed parts of the two ends are grinded, a looser tolerance range is allowed, or strict requirements on dimensions are not required.

3-6. Acting length: When the coil spring is compressed or stretched to a certain fixed length, it should have the value of the counteracting force in order to make the matched items work.

3-7. Free angle: the angle value when the two legs of the torsion spring are not rotated by external force. Generally speaking, the angle formed between the two legs of the torsion spring is not easy to be exactly the same in the free state, and it is not required unless necessary for special occasions, or a relatively loose tolerance range is allowed.

3-8. Action angle: When the two ends of the torsion spring are twisted to a certain fixed angle in different directions, there should be a reaction load value and a torque value in order to make the matched items work.

3-9. Spring constant: the reaction force generated in each unit length when the axial direction of the tension and compression coil spring is deformed by an external force. Or the reaction force generated in each unit angle when the torsion spring is rotated by an external force in the radial direction.

※ In the corresponding graph whose length is the abscissa and the force is the ordinate, the intersections are almost connected into a straight line.

3-10. Length unit: mm (millimeter) is generally used, and inch (inch) is used in Europe and America.

3-11. Load unit: The standard unit of force is N (Newton), or Kgf (kg-force) gf (gram-force) is commonly used.

※ If the length unit is inch (inch), it is customary in Europe and America to use Lb (pound) as the load unit