How Does a Load Cell Work?

How to Connect Your Scale to a ComputerWhile you might not realize it, load cells are everywhere. Almost every single piece of equipment that incorporates a scale somehow relies on one, so there’s a good chance you used one today even if you went 100 miles away from your company’s workshop.

Whether you’re weighing produce at a grocery store or stepping on the simple scale in your bathroom, you’ve more than likely interacted with one recently. Many technicians aren’t even aware of how they work, which is ironic considering how ubiquitous they are.

At their most basic, load cells consist of some sort of spring element that strain gauges have been mounted to. Traditionally, these springs are made of a type of aluminum that’s relatively sturdy. It’s also inexpensive, which has given it a certain reputation for being cheap.

However, at Arlyn Scales, we’ve elected to only use genuine stainless steel when making load cells. Stainless steel comes in a variety of grades, so our engineers have devoted a great deal of research into finding which types of steel are best for our particular situation.

Once a load is placed on the platform of the scale these cells are attached to, the steel gets slightly deformed under the load. That’s what allows a scale to collect information on objects.

Harvesting Information From Load Cells

As soon as you remove the load, the cells should return to their normal state. In fact, Arlyn’s designers have worked hard to ensure that every scale we ship comes with load cells that will last a great period of time and respond elastically to every load they come into contact with.

During the brief time the load cells are stretched, they also stretch the attached strain gauges. These components react to small changes in the load cell and thus become slightly deformed themselves.

In a modern electronic scale, the deformation of these gauges is interpreted by a circuit to determine the weight. When strain gauges are deformed, their electrical resistance changes somewhat. Since these resistors are wired together to form a Wheatstone bridge, it’s possible to monitor these resistance changes by checking the difference in the output of the bridge.

Digital load cells have also come into their own as a field of research.

The Inner Workings Of Digitized Load Cells

A strain gauge load cell can work as a weight transducer. In this case, it works much like a spring that responds in an extremely predictable fashion whenever a downward force acts on it. When the force is removed, the load cell pops back to its original dimensions. Stainless steel components won’t become warped under normal circumstances since they’re designed to take loads in this fashion.

Attached to this load cell is a series of resistors made of flat metallic folds. When the cell bends the strain gauges become stretched, which in turn changes their resistance to a figure that’s proportional to the amount of force that’s acting on the cell.

An output signal registered from the strain gauges is sent to a special circuit that converts analog data regarding the difference in electrical potential between two points to a digital signal. Ordinary scales that work in this way have a resolution of around 1 part in 5,000.

Engineers from Arlyn have developed a special line of ultra-precision devices that use Surface Acoustic Wave (SAW) technology, which doesn’t rely on traditional stress-based measurements at all. These scales employ solid-state transducers to monitor frequency changes.

Since this frequency measure is already digital, there’s no need to convert between two different types of signals. That improves the accuracy of them by several orders of magnitude.

Finding The Best Load Cells For Your Company’s Use Case

Numerous choices await anyone who is doing some research on the best type of load cells for the kind of work they’re doing. One thing that makes your choice a bit easier is the fact that Arlyn Scales only ever feature the highest grade of stainless steel possible for any specific type of weighing unit, so you won’t have to labor too much over your decision.

Contact us online today for more information and a knowledgeable member of our staff will help you find a long-lasting model that gets the job done.