Strain Gauge Load Cell Basics: Definition and Working Principles

Many industrial scales use strain gauge load cells for accurate measurement. In fact, they are the standard for when a force is applied to a scale and then converted into electrical energy. That is why scale operators can troubleshoot if they know strain gauge load cell basics. If you know the working principle and what makes the strain gauge different from other load cells, then you can figure out how to make repairs when they end up in trouble.

What Is A Strain Gauge Load Cell?

A strain gauge load cell is a cell that uses tension to generate sufficient mechanical energy. Generally, it consists of an arrangement of wire called a strain gauge, and a metal body which is called a spring element.

This metal body is usually made of aluminum or stainless steel, to account for necessary flexibility and durability for heavier products. We don’t recommend bodies that contain titanium, cast iron, silica, or plastic since they tend to result in less accurate results. The spring element changes shape when a force is applied, and that allows for the conversion needed. It then will resume its original shape, creating resistance.

Generally, a load cell is a transducer that converts bending, shear, pressure, tension, or compression to electrical energy and displays it as a unit of mass or torque. These four forces are also called mechanical energy and within a scale are generated when an object for weighing is placed on it. Different output signals apply to various types of load cells, which can also cover pneumatic or hydraulic forces.

The strain gauge is named for its structural arrangement attached to a tiny body called a carrier. This is a type of foil sensor. It is composed of wires that are arranged in a grid pattern. This pattern becomes very responsive to changes in mechanical force, and it responds with resistance.

Types Of Strain Gauges And Their Respective Purposes

Strain gauges can either be linear or shear. This refers to how the wires are arranged along the body. Angles will affect the type of measurement that the strain gauge can handle specifically, in reference to biaxial stress or the various forces.

In linear strain gauges, the wires are arranged parallel to the main sensor body’s edges. They handle bending and axial forces when the latter is applied to the strain gauge.

What’s more, load cells can have multiple strain gauges to increase accuracy. They can be aligned at different angles or placed parallel to each other. The number of grids will factor in with the best usage of measuring the force in question as well as the sensitivity level.

A cell with a single strain gauge is called a quarter-bridge. When there are two strain gauges, it is called a half-bridge. You will often see them in precision load cells for manufacturing. These half-bridge gauges are used for circumstances that have limited bridge widths.

When you have a strain gauge with three grids, these are called rosettes. You’ll often see them arranged in varying degrees of 45, 90, or 180 in some instances and 0, 60, and 120 in others. They measure biaxial stress states when you have no principled directions.

Double linear strain gauge cells are one example, where the parallel wires are arranged in two grids instead of one. These are used for the bending beam measurements, for the sake of accuracy.

Sheer strain gauges, in contrast, are arranged at a 45-degree angle to the sensor’s sides. For this reason, another term for them is V-shaped cells. They are specialized in handling a sheer force with two strain gauges for them, as well as for handling torsion bars.

90-degree strain gauges also called T-rosettes, are used for measuring tensions and compression bars. They also analyze biaxial stress states when there are principal directions.

Tension and compression load cells vary in how their strain gauges respond with resistance. When a strain gauge encounters tension, it will lengthen and become thinner. This increases the amount of resistance involved. In contrast, when the strain gauge encounters compression, it will shorten and become thicker.

Improve Your Tension And Compression With Arlyn Scales

Arlyn Scales has spent years outfitting our industrial and manufacturing scales with load cells designed to handle the weight that you place. We research the latest technology to implement into our equipment to ensure that it can handle any environment or demand. Strain gauge load cells are one of our specialties within industrial scales.

Reach out to us today to get started with your strain gauge load cells and scales designed for precision and accuracy. Arlyn Scales will get you locked and loaded for weighing pallets, with the newest strain gauges designed for business purposes. Let us add some load-bearing elasticity to your life, and educate you on the principles of strain gauges.