How Does a Load Cell Work?
Have you ever wondered how your digital scale operates? It’s all thanks to the load cell hidden inside the machinery. Though load cells are complicated, this blog will be an easy-to-follow dive into what load cells are, how they work, and the five most common types.
What is a Load Cell?
A load cell is a transducer, which is a device that converts the pressure of your item into an electrical signal. The electrical signal translates the pressure into weight and displays it on your digital scale.
How Does a Load Cell Work?
Load cells are typically made from slightly flexible materials, such as stainless steel or aluminium. This is important, since when you apply weight to the pan or hook, the pressure flexes the load cell.
Electrical sensors, called strain gauges, detect how much the object flexed the metal, which it converts into an electrical signal. The signal is sent to your scale’s internal computer, and translated to a weight that gets displayed on the screen. Essentially, the weight of your product is the amount of force it took to flex the load cell to the degree that it did.
When the weight is removed from the pan or hook, the load cell reverts to its original state. This is also a good lesson on why it’s important to respect the capacity of your scale. Load cells may be able to bounce back into shape, but not if the weight of your item is significantly heavier than it’s built for.
Types of Load Cells and Their Purposes
There are many different types of load cells, but The Measurement Shop currently stocks five different types, so we’ll focus on those.
S-Type Load Cells
S-Type load cells are identifiable by their shape, which resembles an S or a Z. This shape makes them unique because they can be flexed via both compression and tension forces. The center beam of the load cell contains a strain gauge, which is what measures and converts the force from your item into the electrical output that becomes your weight.
They’re particularly ideal for use in crane or hanging scales, but they can also be used to convert mechanical scales into digital scales. This process involves replacing the in-balance hardware and springs with the S-Type Load Cell.
We offer four different S-Type load cells, with capacities ranging from 50kg to 30 tonnes for a wide range of needs.
Shear Beam Load Cells
Shear beam load cells are shaped like rectangular bars, with one side thicker than the other. This design helps them withstand and accurately measure shear forces. Shear forces are forces that act in opposite directions, as opposed to regular tension or compression forces that act in one direction. Imagine tearing a sheet of paper – you’re applying a shear force to that paper, pulling in two different directions.
There are two different kinds of shear beam load cells: single-ended and double ended. Single-ended load cells are mounted on one side, held steady, while the weight is applied to the other side. Double-ended are mounted on both sides, with the weight applied to the middle. They’re typically found in industrial scales thanks to their accuracy and durability.
The Measurement Shop stocks seven shear beam load cells, with capacities from 100 kg to 50 tonnes.
Single Point Load Cells
Single Point load cells are designed to be better at measuring off-centre loads or loads that don’t cause the load cell to bend at exactly where the strain gauges are (in the middle, typically). For example, if you don’t set the item you’re using in the centre of a platform scale, but rather off to the side, single point load cells can still accurately determine the weight. This is because of their symmetrical inner workings, which means both sides work equally.
Many of the single point load cells that The Measurement Shop supplies are IP rated for protection against dust and water. Depending on your needs, we have IP65 all the way to fully waterproof IP68. We stock single point load cells with capacities between 2kg and 2000kg.
Bending Beam Load Cells
Bending beam load cells are cylindrical shaped load cells that resemble a spring. We stock one bending beam load cell, the BM11 by Zemic. The BM11 has ten models that can handle between 5kg and 500kg to cover all you’re weighing needs. Bending beam load cells like the BM11 are frequently used in retail and shop scales, as well as pallet and platform scales. It’s IP68 rated, fully waterproof, for any outdoor or messy environments.
Compression Load Cells
Compression load cells are particularly tough, as the BM14C that we stock offers lightning protection up to 10,000 volts, with automatic recovery. The BM14C also offers ten models, however, these models have capacities between 1 tonne and 14 tonnes, so they’re primarily used for extremely heavy-duty applications such as in vehicle and truck scales.
If you need help choosing the best load cell for your application, give us a call, we’d be happy to help!