what is the Bimetal ?

The thermo-bimetal is a composite material, made of 2 layers of (mainly Fe+Ni) metal,
having different expansion coefficients, and bonded together by lamination process.
The obtained strip has the property to change its curvature, under temperature variation.

the bimetal forming

The proper choice of bimetal grade and dimensions allows to ensure,
through an adapted forming, as well as a particular fabrication process:

A specific motion

Slow deflection or snap action
(sharp motion)

A mechanical force

... adapted to environment
system constraints

A stroke

... as a function of
a temperature range

Specific temperatures

Snap action and Reset
(unSnap action), according to
a Hysteresis pattern

A reset

... automatic
or manual

An accuracy, a reliability and a sustainability

... which challenges most of the competing technologies

A bimetal thermal and mechanical properties

Once it is cut and formed, the bimetal performs the function of regulation or security, otherwise it actuates:
• An electrical switch
• An air or a liquid inlet valve
• Any kind of mechanical system

The bimetal uses to operate

• Either the natural temperature of the environment it is supposed to measure
• Or an electrically warmed component (like a thermistor)
Such a system is better than an electromagnet, for the same function

The snap action specific bimetal

Then snap action forming gives it a bi-stable characteristic: Hysteresis curve, with a high temperature triggering and a low temperature reset (or vice-versa: low temperature triggering and high temperature reset)

Courbe Hysteresis

The bimetal here on the right snaps at an accurate specified temperature, and automatically resets (unsnaps) when it cools down.

The bimetal Technology advantages

Simple and low cost

A simple piece of métal is able
to work both as a thermal
sensor and a valve actuator


The bimetal generally doesn't need
any electrical energy to operate


The bimétal is recyclable


No customer return
since the last 10 years
of production


Very low characteristics drift,
after years, or millions
of cycles.


The functional control is possible
at any time, without any destructive effect
(like electrical or thermal fuses)

The bimetal applications

Domestic appliance

Temperature regulation, anti-drip system for steam irons, oven security lock, overheating security, fridge door open security ...


Overheating detection
of a defective component


Automotive motor fan switch, fire sensor, fluid thermal valve,
Thermo-contact de mise en route du ventilateur moteur, capteur incendie, vanne thermique de circuit de fluide, verrouillage de gas flap lock ...


Thermostat, chimney or insert flap control, patio heater flap control, boiler valve control ...


Fire sensors, fire door lock ...


Cold chain interruption indicator, regulation thermostat, medicament supply mean thermal lock ...


Cold chain interruption

Ventilation & Air conditioning

Fire sensor, temperature monitoring sensor ...


Shock absorber for humanitarian supply dropping parachutes, satellite battery overheating sensor, miscellaneous thermal sensors and actuators ...

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