Load Cells

Load cells are electronic devices that are used in weighing scales and mechanical test cells to measure the load, compression, tension and shear force of an object. The output force can be given as either voltage, current or digital readouts. Load cells are very similar to tensile testers.

Load cells generally consist of four strain gauges in a wheatstone bridge configuration, however they are also available with one or two strain gauges. The electrical signal output is usually in the range of a few milivolts and it needs to be amplified by an instrumentation amplifier before it can be used. The output of the transducer is plugged into an algorithm to calculate the force applied to the transducer.

Although electronic load cells are the most common type, there are other types of load cells. The hydraulic or hydrostatic load cell is also a common type. These other technologies are used to eliminate any problems with electronic load cell devices. For instance, a hydraulic load cell is immune to transient voltages such as lightening so it may be a more effective type of load cell in outdoor environments.

During operation, "load cell ringing" can often occur. This vibration of the load cell takes place when the load cell is subjected to a relatively high force. An oscillating data pattern can be the result.

While ordering load cells, you need to mention the range of load to be measured and the force and accuracy desired. You can arrange the load cells so that they measure load in two or three axis. There are different types of load cells and these are: compression (used to measure compressive forces that crush along a straight axis), tension (used to measure forces that pull apart along an axis), and shear (to combine the tension and compression, but at an offset axis).

Sensors that are used in load cells are either of piezo electric-type or of the strain gage-type. Load cells are offered as packages like: pancake, S-beam, miniature, load pin, donut, washer, plate, platform, bolt, link, cantilever, canister, rod end, etc. Adjustment for variation in operating temperatures, shock and vibration can also be specified.

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