The load cell is mainly used to measure weight. It is used in various electronic weighing instruments, industrial control fields, online control, installation overload alarms, material testing machines and other fields. The application equipment includes electronic truck scales, electronic platform scales, electronic forklifts, and dynamic axles. Weighing scales, electronic hook scales, electronic pricing scales, electronic steel scales, electronic rail scales, hopper scales, batching scales, filling scales, etc. Load cells generally cannot be found directly because they are usually hidden in the equipment and belong to accessories.
The load cell consists of an elastomer with strain gauges. Elastomers are usually made of steel or aluminum and are very strong and have very little elastic deformation. As the term “elastic body” puts it, steel or aluminum undergoes a certain amount of deformation under load, but then returns to its original position and responds elastically to each load. These very small changes can be obtained with strain gauges. The deformation of the strain gauge is interpreted by the electronic instrument to determine the weight.
To understand the last point, we need to explain strain gauges in more detail: they are electrical conductors that are firmly attached to the substrate in a meandering manner. When the substrate is pulled, it grows longer with the electrical conductor. When it shrinks, it becomes shorter. This will cause a change in the resistance in the electrical conductor.
The strain gauge is firmly fixed to the elastomer, so it undergoes the same deformation. For the load cell, these strain gauges are arranged in the Wheatstone bridge (as shown in the figure below). This means that four strain gauges are connected to form a bridge, and the direction of the force to be measured is aligned with the measurement grid wire.
If an object is placed on or suspended from the load cell, the weight of the object can be determined. The expected load of the load cell is always along the direction of the center of the earth, that is, the direction of gravity, that is, only the force component of the direction of the load’s gravity can be obtained. This is not the case with the force sensor. Although the design is similar, the force sensor can capture loads occurring in all directions, regardless of the direction of the earth’s gravity and the installation method.
Several suggestions for selecting load cell
1.Choose a larger capacity. For example, if your normal use is 150kg, then it is recommended that you use 200kg, which will increase the service life of the sensor.
2. Choose your shape. There are tension and pressure, spoke type, three-dimensional force, single shear beam type, double shear beam type, bellows and so on.
Weighing sensor parameters are selected from several aspects:
Sensitivity, comprehensive error, repeatability, hysteresis, creep, temperature range, working range, output resistance, input resistance, insulation resistance, safety overload, limit overload and other main parameters.