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

Autonomous

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

Ecological

The bimétal is recyclable

Reliable

No customer return
since the last 10 years
of production

Sustainable

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

Testable

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 ...

Electronics

Overheating detection
of a defective component

Transport

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 ...

Heating

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

Fire

Fire sensors, fire door lock ...

Medical

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

Alimentary

Cold chain interruption
indicator

Ventilation & Air conditioning

Fire sensor, temperature monitoring sensor ...

Aeronautics

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

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