are close-coiled helical springs designed to resist twist or rotation forces from
two directions. A
consists of a body of coils and two legs attached to other components. When the
ends rotate around the center of the spring, the spring tries to push them back
to their original position.
The body coils are close-wound with minimal tension between the coils. You can design
with open-wound coils to reduce friction or when the spring needs to perform as
are made of round wire with straight legs.
Optimum Spring Solutions
in different lengths and degrees of tension to suit your specifications.
To help you solve basic torsion spring design challenges, please visit our
Torsion Spring Design Alternatives Guide.
Table of contents:
Common spring ends we manufacture depend on:
- Leg angle
- Leg length
- Leg end style: straight torsion, straight offset, hinged, short hook end
Special considerations should be given when choosing a leg configuration for your
The recommended allowable hook stress in torsion is 30-45% of its minimal tensile
strength depending on
while that for bending is 75% of its minimal tensile strength.
legs that are straight or parallel on the same side are considered to have a 0º
leg angle. The increasing angle is in the unwinding direction.
When the ends rotate around the center of the spring, the spring tries to push them
back to their original position.
- d (Wire Diameter): Wire diameter for the
- Dd (Shaft): Maximum diameter of a spring shaft in
are usually mounted over a shaft, mandrel, or arbor.
- Di (Internal/Inside Diameter): Calculated by subtracting
two times the wire diameter from the external diameter of a spring. Internal diameter
decreases while the spring is working even up to shaft diameter.
- De (External/Outside Diameter): Calculated by adding
the internal diameter plus two times the wire diameter of a spring.
- L0 (Free Length): Overall length of a spring in
unloaded position. Free Length decrease while spring is working.
- Ls (Leg Length): Distance from the center axis of
the coil body to the end of a leg of a
Torsion spring end style is straight legs.
- Number of coils: Total number of coils in a spring.
- An (Maximum Angle): Maximum acceptable rotation
angle for the spring in degrees.
- Fn (Maximum Force): Maximum acceptable force that
can operate at the end of a leg of a
- Mn (Maximum Torque): Maximum acceptable torque in
lb*in or Newton*mm.
- R (Spring Rate/Stiffness): Angular return torque
provided per unit of angular displacement in pounds per inch (lb/in) or Newtons
per millimeter (N/mm).
- A1 & F1 & M1: (Angle at Torque or Force)
To calculate the angle as a function of the torque:
A1 = M1/R
To calculate the torque from the force: M = F*Ls
- Leg positions: 0, 90,180 or 270 degrees.
- Helix Direction: Right or left-handed. A left-handed
spring loads in a clockwise direction. Since force is applied to torque and not
deflection, right and left can not be interchanged.
with a wire diameter of 0.004" up to 0.120" (0.1mm to 3.0mm)
are the most common
we use to manufacture
extension springs. Other materials we use and
their properties are listed in the
Round wire is most commonly used for
because it is most adaptable to standard coiler tooling. We can manufacture
with square, rectangular and special wire sections.
- Operating Environment
- Service Life /Fatigue
Formulas for torque are in inch pounds. When a force is specified at a distance
from the centerline, the torque, is called the moment, is equal to the force multiplied
by the distance. Rate calculations for
must consider friction between adjacent coils as well as friction between the
body and the arbor over which it revolves.
are mounted over a rod or shaft. Suggested shaft diameter should leave 10% clearance
within the inside diameter of the
for deflections. For greater deflections, reduce the shaft size. As
assumes a load and the body length enlarges, the body diameter will reduce. Take
this into account when design space is limited.
We offer fast turnaround on small, medium and large runs. In addition, we welcome
projects which require limited quantities. Our design specialists offer you specific
advice and design review during the
go into many applications for diverse industries that require high-quality coil
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for immediate service or complete our Request for Quote Form.