In the past, the weight of an unknown object was measured by balancing it out on the other side of the scale with known weights. This method of weight measurement gave a reliable estimation of the weight of an object.
However, there was still a need to develop more accurate weight-measuring tools for use in complex commercial, manufacturing, and research applications. A load cell is a device that is used globally to measure force and hence the weight of different objects accurately.
This article explores everything you need to know about load cells, their working, and possible applications. So, if you are completely unfamiliar with load cells or you wish to know more about how they work then keep on reading till the end.
What are Load Cells?
Load Cells: Principle and Working
Types of Load Cells and Their Uses
- Single Point Load Cell
- Compression Load Cell
- Pneumatic Load Cell
- Piezoelectric Load Cell
- Hydraulic Load Cell
- Strain Gauge Load Cell
- Magnetostrictive Load Cell
- Bending Beam
- S-Beam Load Cell
- Tension Load Cell
Applications of Load Cells
What are Load Cells?
A load cell is a type of gauge or a transducer technology that creates an electrical signal of magnitude that corresponds to the amount of force being applied to it.
This sensitive tool can convert forces of tension, compression, torque, or pressure into a measurable electrical output signal that shows the actual weight of an object.
Load cells are available in a wide range of shapes and designs based on their intended applications and deformation-measuring technologies.
Load Cells: Principle and Working
The basic principle of the load cell is as follows:
When a force or stress is applied to the load cell, there is some stretching or bending which changes the state of the strain gauge (an elastic stainless-steel material fixed inside the load cells).
This physical change in the strain gauge leads to a change in the electrical resistivity and that changes the output voltage. This way you can get a very accurate value for the weight of an object.
The load cell works by measuring weight using an internal mechanism that consists of a spring and a strain gauge. The strain gauge converts internal deformation caused by the weight of the object into an electrical signal.
There is also an electric conductor attached to a film which contracts or elongates based on the type of force it experiences. This change in the film changes the resistance in the conductor which is what load cells measure and convert into digital readings.
Types of Load Cells
Following are some of the most commonly used types of load cells that find applications in various fields:
- Single Point Load Cell
Single point load cells are ideal for applications where the centering of load is not possible. There is a cut-out in the middle of the mechanical body which allows the cell to ignore the torsions resulting from the decentralization of the loads.
This allows you to correctly weigh the applied force and hence the mass of the object under consideration.
- Compression Load Cell
This type of load cell consists of a circular diaphragm which is deformable. The thickness of this diaphragm depends on the capacity of the load cell and the intended application.
This load cell measures pushing force along a single axis making it an ideal choice for different types of weighing scales and in applications with limited space.
- Pneumatic Load Cell
These load cells use the force-balance principle to provide highly accurate readings. These consist of multiple dampener chambers and an elastic diaphragm attached to a platform.
There is also an air regulator to limit the air flow to the system as well as the pressure gauge. When an unknown weight is placed on the load cell, it uses the air or gas pressure to balance it out and the amount of air needed for that gives you the actual value of the weight.
- Piezoelectric Load Cell
In this type of load cell, the voltage output is generated by a piezoelectric material. These load cells are ideal for dynamic weighing applications as they can be directly linked to a readout meter.
- Hydraulic Load Cell
These load cells also work on the force-balance principle. They measure the weight as a change in the pressure of some internal filling fluid like water or oil. When a force acts on the loading head, it is transferred to a piston which compresses the fluid present in the elastomeric diaphragm chamber.
The pressure on the liquid is proportional to the weight which is converted into an electrical signal from a pressure sensor.
- Strain Gauge Load Cell
This type of load cell undergoes a change in electrical resistance when under stress. In this case, a strain gauge assembly is placed inside the cell to convert the load acting on it into electrical output.
These load cells are further connected to electrical circuits to detect minute changes in the resistance due to strain. In this load cell, four electrically connected strain gauge elements are used which form a Wheatstone bridge circuit. Two of the said elements are in compression while the other two are in tension.
In the presence of the load, the resistance of the strain gauges varies which leads to voltage fluctuations. These fluctuations are measured and converted into readable weight values.
- Magnetostrictive Load Cell
This load cell measures the change in permeability of the ferromagnetic materials when acted upon by stress. It consists of a stack of laminations that forms a load-bearing column around primary and secondary transformer windings.
The action of force changes the magnetic flux pattern which changes the output signal accordingly.
- Bending Beam
These load cells operate on the self-deformation principle where some part of the cell is reduced using holes. When load is applied there is some deformation or bending which is measured to get the value of the weight.
- S-Beam Load Cell
S-Beam or Shear Beam load cell that is used for applications under 22 kg or 50lb. These cells come in an S shape and they feature a metal spring that undergoes deformation under stress.
The strain gauge used in the S-type load cell detects the extent of deformation giving you an accurate value of the weight.
- Tension Load Cell
These load cells consist of a strain gauge that measures the pulling force along a single axis. These load cells are mostly used in space-restricted applications where the load can change from tension to compression and vice versa.
Applications of Load Cells
Following are the main industries and applications that utilize load cells
- They are used in the food processing industry to measure the proper distribution of ingredients and prepare final products.
- Load cells are used in the construction industry to test building materials like beams for tension and strength.
- These are used in scales for measuring trucks and railroad cars.
- Research and pharmaceutical industries use these for calibrating weighing scales.
- They are also an important component of personal weighing scales, security systems, material testing, etc.
- You can also use these for measuring loads in struts, tiebacks, cables, and foundation anchors.
Conclusion
Load cells have really transformed the way we measure weights both in personal and commercial applications. These devices allow you to record even the smallest variations in the weight giving a reliable output every single time.
The choice of load cell depends on your particular application and the sensitivity and accuracy requirements. When choosing a load cell, it is better to do your research first to find a product that meets your weight capacity requirements as well as quality standards.
Visit Accurate Meezan today to explore our wide range of premium-quality load cells for all applications.
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