What Is A Load Cell And How Does It Work?

Load cells are transducers that convert mechanical energy into electrical signals. This mechanical energy tends to be a force like pressure, tension, compression, or torque.

In short, these devices assist when weight provides any of these forces. Load cells can either be used in strain gauges, hydraulics, and pneumatics. At Arlyn Scales, we tend to implement strain gauge load cells into our equipment because they assist in providing the most accurate weight of products or raw materials within a range of .03 to .025 percent.

Types Of Load Cells

Strain Gauge Load Cells

Strain gauge load cells are the most commonly used type for industrial environments in terms of electronic scales. The forces involved include tension and compression. Load cell bodies tend to be made of stainless steel, aluminum, or a steel alloy. These metals often have a high-temperature threshold and durability, meaning the loading cell body will last for a long time. That’s why they help reduce operating costs for the employees in question and deliver accurate readings on a consistent basis.

There are many types of strain gauge load cells: bending beams, low buttons, pancakes, single-point, and double-ended shear beams, canister loads, wire rope, tension links, load pins, and S-type load cells. While a few overlap in their purposes and benefits, you will see differing uses depending on the task at hand.

Some like tension link load cells simple measure tension while others are used for more heavy-duty operations such as for cranes in construction and transportation of goods. S-type and canister load cells can use both tension and pressure to generate the energy needed for signals.

Pneumatic Load Cells

Pneumatic load cells use air pressure to generate the energy needed to create electrical signals. It usually has a diaphragm where one end receives the incoming air and the other has a nozzle for expelling it. The diaphragm deflects and measures

You will see pneumatics used in environments that have a risk of fires or explosions from combustible material and electric sparks. Alternatively, they are used in industries like food processing that require extremely clean environments. Air pressure is considered to be relatively cleaner and uses a renewable source of energy, which provides two added benefits.

One trade-off, however, is that the air itself must be kept clean. Operators will use either the natural air in the environment or nitrogen, with the latter being expensive. The air expelled must be breathable for humans, and be filtered of elements that can clog or damage the machine such as water droplets or microscopic sediments. Pneumatics can also be slow-going, which makes it more unsuitable for operations that demand a high output.

Hydraulic Load Cells

Hydraulic load cells use oil to generate necessary pressure. The diaphragm generates pressure by reducing the volume of the oil. A high-pressure hose helps transfer the reading to the pressure gauge, with a Bourdon tube recording it.

Operators will use hydraulic load cells when they need to conduct work remotely. As an added benefit, they require no external power supply which makes them suitable for such a task and requires no electrical components. This means they can be used more often in areas that are prone to sudden high voltages, like outdoor fields prone to thunderstorms, or that are hazardous to human workers. They are also fairly accurate with a range of .25% for a margin of error.

One trade-off, however, is that hydraulic cells are highly expensive. The cost of the technology has not sufficiently decreased for it to be used in the mainstream. Until that changes, then you are more likely to see it used in special circumstances.

How Does A Load Cell Convert Output Signals?

The load cell’s body is also called a spring element, owing to its elastic qualities. It is connected to a strain gauge, which is usually a flexible wire grid that generates the tension needed to convert the compression force. An application of force will cause the spring element to deform or change shape. That’s why elastic metals are preferable.

When the spring element changes shape on encountering force, it also changes the strain gauge’s shape. The strain gauge will stretch under tension, and compress under pressure. Voltage results from the change in resistance within the strain gauges as the spring element returns to its original shape.

Measure Weight Accurately With Equipment From Arlyn Scales

At Arlyn Scales, precision, accuracy, and practicality are our priorities. We have spent years designing industrial scales that can measure raw materials, packages, and even livestock depending on the environment. Our specialists look into the newest technology to improve our strain gauge cells.
Reach out to us today to learn more about our load cell designs. Arlyn Scales is ready to educate you on how engineering can meet your business needs and handle output signals. Let us improve your load cells to ensure that your weighing needs are met efficiently.