WHAT IS A LOAD CELL?

A load cell is a device that converts a mechanical movement into an electrical signal. It’s as simple as that. Used with an indicator and pcl, it gives you important force information or feeds it to a process system.

Load cells have become commonplace in a wide variety of applications. A typical example is weighing scales at a supermarket checkout. When the operator places, say, a bag of tomatoes on the scale the indicator displays both the weight and the price per kilo.

The most common type of load cell consists of sensors called strain gauges bonded to the surface of components made from specially designed and manufactured metal. The strain gauges are wired into an electrical circuit called a Wheatstone bridge, and the output is displayed on the indicator.

At Proctor & Chester, we supply both a range of standard load cells and offer an in-house design service for custom load cells that meet your exact requirements.
For more information about strain gauges, go to: www.strain-gauging.com

SPRING INTO ACTION!

Spring Element

The most critical mechanical component in a load cell is the Spring Element. It acts as a reaction to externally applied loads and distributes that load into a uniform strain path. This is then measured by the strain gauge which provides an accurate measurement on the Wheatstone bridge.

There are several parameters that need to be considered in the design stages of the load cell to provide a high performance unit. Things like:

• The maximum applied force.
• Whether it’s a static or dynamic application.
• The load alignment.
• Non linearity CAD PICTURE of graph.
• Hysteresis.
• Repeatability.
• The effects of temperature on both zero and output.
• Creep.
• Any sudden impact forces.

The load cell itself is a passive device. To make it operational you must link it up to an external instrument or amplifier.

Load cells are used for applications in a wide variety of industries:

• In shops for scales. And in banks to count money.
• In all kinds of vehicles, ships, aeroplanes and space craft.
• In military vehicles. And in agricultural machinery, racing cars and bikes.
• In bridges, buildings and dams.
• In lifting machinery such as cranes and elevators.
• For process control and in farming.
• And for medical applications and in university departments.

Indeed, you can use load cells in virtually every industry you can think of.