Load cells for scales: understand how it works
Load cells for scales go unnoticed, but they are present in our daily lives. When we go to the market and need to weigh food before buying it, when we weigh ourselves at the pharmacy, or when we buy an industrialized product, we don't realize it, but we use this technology for almost everything and, therefore, it is so fundamental.
Weight is important for all sectors around us. Industry needs to weigh products during the manufacturing process and the sale. The market buys and sells food in the same way. It wouldn't be different with the transport sector, would it?
Can you imagine the application of load cells for scales on railroads? So, it is. Trains are often heavy. This implies an imposition for them to operate within norms that ensure the durability of the railroad network, the safety of operators, fuel energy efficiency and time savings.
In this article we will talk about the importance of this technology, how it works and its applications in different sectors.
Content Index
How a Load Cell Works
As they are electromechanical sensors, load cells for scales work by combining two principles. The first is mechanical deformation, caused by pressure on the material that makes up the cell. Generally, steel is used for the various types of cells, from the most precise classes to the least precise ones.
The second important principle for the functioning of the cell is the variation in electrical resistance, which can occur according to the length of the electrical circuit being measured. Thus, when placing an object on the pressure cells, they present a mechanical deformation, together with the built-in electrical circuit. The greater the length of this circuit, the greater the electrical resistance.
Then, an electronic circuit reads the variation of electrical resistance in the circuit until the cell returns to its initial state, without deformation. To calculate the resistance, the electronic circuit measures the input voltage of the circuit, the output voltage and compares their values.
Cell deformation cannot be permanent. Therefore, it is essential that the chosen material has mechanical strength, to support large weights, but with considerable elasticity, even with micro variations. Therefore, the most common choices among load cells for scales are steel and aluminum.
These materials must also be resistant to external influences. Just imagine weighing the same material in different places or on different days. Climate change can impose temperature extremes in very short periods, which interferes with the volume of cells and the accuracy of their weighing. Therefore, materials with low contraction and expansion in environments from 0 to 60 degrees Celsius.
Use of load cells in scales
There are cell variations to match different applications in industry and in different sectors. The most common on the market are load cells, beam, traction and single point.
Furthermore, the application is related to the accuracy of these components. Load cells for industrial scales are usually more robust and withstand pressures in the order of tons, while those used in weighing in a supermarket do not need to support more than forty kilograms and are used to differentiate grams.
With the improvement of the technology of these components, new applications begin to appear. An example is the measurement of water resistance on triathlon suits. The lower the pressure identified by the cells, the greater the performance of the mesh while the athletes swim.
The industry has also diversified the use of load cells for scales in industrial automation. The ability to measure pressures and identify the mass of objects helps build systems such as machines for packing grain. These are dumped into a package until the system identifies the limit weight and processes a signal to close the package.
Technological trends
Among the countless applications of weighing, different sectors benefit and transport is one of them. Weighing freight trains is a routine task, as the railroad transports with a large weight capacity.
Load cells for scales are available in different types of weighing, namely static, dynamic, flow and batch weighing. Dynamic weighing was developed with the intention of reducing operating costs and facilitating the railroad logistics process. In the dynamic scales manufactured by Massa, the rail of the railroad is used as a mechanical deformation element, that is, it is not necessary to add another element for weighing, what is done is to measure the mechanical deformation of the rail between two sleepers when the train wheel passes over the track. This load cell model has the advantage of having no elements disconnected from the track.
While the static scale works with the train stationary, the dynamic scale can weigh a train up to 10 km/h, which reduces operating time and fuel spent on maneuvers to put the train on the weighing tracks, part by part. It may not seem like it, but the maneuvers are done on a daily basis and have an influence on fuel consumption and weighing time can hinder the flow in busy lines.
Another advantage of this type of weighing is safety, since operators are not required to uncouple wagons, recoup them and, therefore, it is possible to reduce the professional maintenance team and certification for work in confined spaces.
Thus, scale load cells are responsible for saving time, energy efficiency and conservation of the railroad network, since there are rules that involve the weight of the wagons so that they can circulate. The limit is established in order to preserve the wheels and rails from excessive wear, or before the expected time, which causes damage to the mesh and can compromise it entirely.
Conclusion: Load cells for scales
So far, we have seen what load cells for scales are, how they work, their applications in industry and in the transport sector. Although there are still possibilities to be explored with its use, this technology is more present in our lives than we imagine.
We use scales in a variety of environments and much of what we consume involves using them during manufacturing and transportation. This is why basic knowledge is so important.
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