Inside every load cell is a piece of specially engineered metal – known as the “spring element” – fitted with tiny sensors called strain gauges. When a load is applied, the metal flexes by a microscopic amount, far too small to see, but more than enough to make a difference.
As the metal deforms, the strain gauges stretch or compress with it, changing their electrical resistance ever so slightly. This alters the voltage passing through them, producing a small electrical signal that is directly proportional to the force applied.
That signal can then be connected to a weighing amplifier or indicator which, once calibrated, converts it into the weight reading you see on the display.
Here’s the twist – weight and mass aren’t the same thing.
Mass is the amount of matter in an object, and it stays constant. Weight is the force that mass exerts under gravity. Take a 100kg mass to the Moon and it “weighs” six times less, yet its mass hasn’t changed at all. Because load cells measure force, gravity matters and that’s precisely why calibration and traceability are so critical.
From small bench scales to silos handling hundreds of tonnes, it all comes down to force. Regular service and calibration are essential to keep readings accurate, and that’s where our nationwide service team can help; email us at ServiceDesk@aw.co.uk
Did this surprise you? Email your weighing questions and our experts will tackle them in a future post.