can be made from round or square wire, although round is considerably cheaper and easier
to manufacture. We keep a vast selection of material sizes and types in stock, from
standard spring steels to nickel alloys, all of which can be used to manufacture torsion
When ordering a torsion spring, consider the following
Wire size -
Specify either metric or Imperial measurements or Standard Wire Gauges. We stock all the
standard wire sizes and also a large range of non-standard wire sizes for certain designs.
Diameter - Specify the outside
diameter of the main part of the spring, or the size of rod that is to go through the
centre of the spring (if any). The diameter of the spring is inversely proportional to the
rate (strength) of the spring.
Number of coils - The number of
coils is inversely proportional to the rate (strength) of a torsion spring. A large number
of coils will result in a fairly weak spring. A small number of coils will give a
relatively strong spring.
Rate - The rate (strength) of the
spring depends on the above factors and can easily be calculated. The rate is defined as
the torque that has to be applied in order to produce unit deflection and is usually
measured in Newton mm per degree (Nmm/°).
Leg Types - The following are just
four examples of leg arrangements for torsion springs:
[ example ]
[ example ]
|One leg radial over centre,
the other tangential.
There is no standard type of leg configuration for torsion
springs although, obviously, the cost to manufacture will increase as the complexity increases. The simplest (and cheapest) type are the tangential legs, but we are able to
manufacture just about any design you could imagine with multiple bends and/or hooks and
loops. Feel free to contact us to discuss any specific
Index - This is the ratio of the
mean diameter to the wire diameter. A low index indicates a tightly wound spring: a
relatively large wire size wound around a relatively small diameter mandrel giving a high
rate. A high index indicates a more loosely wound spring: a relatively small wire size
wound around a relatively large diameter giving a low rate.
Stresses - Torsion spring stresses
are of great importance. We are able to calculate the stresses within the spring and warm
our customers what the maximum safe deflection is to prevent damage to the spring during
operation. For more technical information contact our design team.
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