Torsion Spring Design Considerations

We currently manufacture torsion springs from all types of wire. Our wire size range is from 0.008" to 0.120" (.15mm to 3.3mm).

RATE - The spring rate, or spring constant, (Hooke’s Law), is usually the most important defining characteristic for any torsion spring. The spring rate is frequently defined by two load requirements at two deflected positions. (Determining the rate this way will 'lock' the free position of the spring.) Specifying the free position and a load at a deflected position will also define the rate.

LOAD - The load of a torsion spring is usually defined as a moment or torque. Lb-in or N-mm are the typical units. Be specific in indicating the load points on the active legs of a torsion spring. All active wire in the torsion spring must be accounted for when calculating load and stress conditions.

DIAMETER - Torsion Spring diameter is restricted by the envelope into which the spring must fit. Torsion springs are typically installed over a rod or pin. As a torsion spring is deflected, or wound up, the body of the spring reduces in diameter. This reduction must be considered when designing the spring. Any binding on the mounting shaft should be avoided.

BODY LENGTH - As the body winds up and the diameter reduces, the body length increases. This increase is equal to one wire thickness for every 360 degree, (1 turn), deflection. This assumes that the torsion spring is close wound. Open wound torsion springs can also be designed, but control of the body length can be difficult to maintain. 

DIRECTION OF HELIX - Helix is almost always important to facilitate the installation and application of the torsion spring. Many applications call for symmetrically opposite torsion springs to be used in conjunction with each other in the same assembly.  Double Torsion springs are typically two symmetrically opposite springs that are connected by a hairpin shaped bend.

TYPES OF LEGS - Almost any leg configuration you can design can be made on the end of a torsion spring. The more complicated the leg design, the more costly the manufacturing process becomes. Straight legs are always cheaper than formed legs. The positional relationship between legs is important to consider as well. This relationship will determine the free position, which will determine the load at the deflected position.

MATERIAL CHOICE - There are almost infinite choices for spring material, suitable for an almost infinite range of spring applications. Contact Maverick Spring Makers Limited for assistance in determining the best choice for your application. The environment in which the spring operates and the required fatigue life of the spring, or assembly in which the spring operates, are key factors to consider when deciding on an appropriate spring material. (Think about operating temperature, static or dynamic loading, shock loading, electrical conductivity, magnetic properties, operating atmosphere, etc.) 

ANY OTHER INFORMATION - Anything you can tell your spring manufacturer about the end use of your component or assembly will help you get the best spring solution. Springs are typically the most critical, if not the most highly stressed, component of an assembly, but are often left until the end of the design stage. Contact Maverick Spring Makers Limited at the start of your design process to find the best spring design solution for your needs.