A load cell also known as a force transducer, is typically crafted from metal, that’s utilized by scales to determine the weight of an object. There’s quite a variety of load cells out there, each with its unique design and function, but we’ll delve deeper into that shortly.
So, how does this load cell work? Essentially, it takes various types of mechanical forces like tension, torque, compression, or pressure, and transforms them into an output signal. This signal then travels through a load cable to the scale’s indicator, where the precise weight can be read by whoever’s operating it.
Now, let’s explore all of this more. The inner workings of this equipment can be a bit complex, especially considering the different types available. Today, we’ll focus on the three most common: hydraulic load cells, pneumatic load cells, and strain gauge load cells.
Strain Gauge Load Cells
These are the most prevalent types you’ll come across, found in almost every modern scale. They work by utilizing a fine wire or metal foil arranged in a grid pattern. As weight is applied to the load cell, these strain gauges convert it into an electrical signal. Typically, four strain gauges are strategically placed for optimal accuracy. Each strain gauge's resistance changes when an object is placed on the scale, resulting in a change in output voltage that is converted into a digital weight measurement.
Pneumatic Load Cells
These are gaining popularity, especially in environments like labs where cleanliness and safety are key. They’re incredibly stable and can withstand extreme temperatures. Unlike hydraulic load cells, they don’t contain fluids that could potentially contaminate surroundings. When an object is placed on the scale, a pressure gauge measures the displacement of pressurized gas (usually air) within an internal diaphragm. Heavier objects cause more deformation in the diaphragm, leading to increased air escaping through a nozzle at the other end of the load cell.
Hydraulic Load Cells
These are entirely mechanical and devoid of any electrical components, making them ideal for industrial and hazardous environments. They work similarly to pneumatic sensors but use oil or another fluid instead of pressurized air. When an object is placed on the scale, the force is transferred to a piston, compressing the oil. Heavier objects create more pressure in the fluid-filled chamber, which is then measured by a hydraulic pressure gauge. This reading is then displayed on an external dial for the operator to record.
Load Cell Applications
It measures physical quantities or mass and transforms force or energy into another form, such as force, light, torque, or motion. They are used for mechanical testing, system monitoring, and industrial-scale components. They are used in a wide range of applications, including household scales and heavy industry measuring instruments.
Conclusion
Weight is measured using load cells, which come in a variety of shapes, sizes, use cases, functioning principles, and applications. They convert a specific type of mechanical force into an output signal, which is commonly tension, torque, compression, or pressure. A load wire is then utilized to transmit this output signal to the scale's display, where the operator may measure and read the actual weight.