What is the hysteresis of S Type Load Cell?

As a supplier of S Type Load Cells, I’ve seen firsthand the importance of understanding the key technical parameters related to these devices, and one such crucial parameter is hysteresis. In the world of load cells, the S Type Load Cell is a popular choice due to its versatility and performance in various applications, from industrial weighing systems to force measurement in scientific research. S Type Load Cell

Understanding the Basics of S Type Load Cells

Before delving into hysteresis, let’s briefly review what an S Type Load Cell is. An S Type Load Cell, also known as an S Beam Load Cell, gets its name from its distinctive S-shaped design. This shape allows it to measure both tension and compression forces effectively. The load cell works on the principle of strain gauges. When a force is applied to the load cell, the S-shaped structure deforms slightly. Strain gauges attached to the structure detect this deformation, which is then converted into an electrical signal proportional to the applied force.

Defining Hysteresis

Hysteresis in an S Type Load Cell refers to the difference in output readings when the same load is applied and then removed. In other words, when a load is gradually increased from zero to a maximum value, the load cell will give a certain output. But when the load is then gradually decreased back to zero, the output may not return exactly to the original zero value. This difference between the output during the loading and unloading process is what we call hysteresis.

Mathematically, hysteresis is often expressed as a percentage of the full – scale output (FSO). For example, if an S Type Load Cell has a full – scale output of 2 mV/V and a hysteresis of 0.05%, the maximum difference between the loading and unloading output at full scale would be 2 mV/V×0.0005 = 0.001 mV/V.

Causes of Hysteresis in S Type Load Cells

There are several factors that can cause hysteresis in S Type Load Cells:

Material Properties: The material used to construct the load cell body plays a significant role. Metals, such as alloy steel or aluminum, which are commonly used in S Type Load Cells, have inherent material characteristics that can lead to hysteresis. When a metal is deformed under load, some internal molecular structures may change. During the unloading process, these structures may not fully return to their original state, resulting in a difference in output.

Strain Gauge Behavior: Strain gauges are essential components of an S Type Load Cell. The bonding between the strain gauges and the load cell body can introduce hysteresis. If the adhesive used to attach the strain gauges does not perform well under cyclic loading, it can cause the strain gauges to move slightly relative to the load cell body. Additionally, the strain gauges themselves may have some non – linear behavior during loading and unloading, contributing to the overall hysteresis.

Mechanical Design and Assembly: The design of the S Type Load Cell, including the way it is machined and assembled, can also affect hysteresis. Factors such as improper alignment of components, excessive stress concentrations in certain areas, or loose connections can all lead to increased hysteresis. For example, if the bolts used to attach the load cell to the measuring system are not tightened evenly, it can cause non – uniform deformation of the load cell, resulting in higher hysteresis.

Impact of Hysteresis on Load Cell Performance

Hysteresis can have a significant impact on the accuracy and reliability of an S Type Load Cell. In applications where precise force or weight measurement is required, such as in calibration laboratories or high – precision manufacturing processes, even a small amount of hysteresis can introduce errors.

For instance, in a batching system where a specific amount of material needs to be dispensed accurately, hysteresis can cause the load cell to report incorrect weights. This can lead to over – or under – batching, which can have a negative impact on product quality and production efficiency.

In long – term applications, hysteresis can also cause cumulative errors. If a load cell is subjected to repeated loading and unloading cycles, the small differences in output due to hysteresis can add up over time, leading to significant deviations from the actual measured values.

Measuring and Controlling Hysteresis

To ensure the quality of our S Type Load Cells, we have strict procedures in place for measuring and controlling hysteresis.

Measurement: We use calibrated testing equipment to measure the hysteresis of each load cell. Typically, we apply a series of increasing and decreasing loads to the load cell and record the corresponding output voltages. The difference between the loading and unloading output at each load point is calculated, and the maximum difference is then expressed as a percentage of the full – scale output.

Control: To control hysteresis, we start with the selection of high – quality materials. We carefully choose metals with good mechanical properties and low internal hysteresis. The manufacturing process is also critical. We use advanced machining techniques to ensure precise dimensions and smooth surfaces of the load cell body. During the assembly process, we pay close attention to the bonding of strain gauges and the alignment of components to minimize any sources of hysteresis.

Applications of S Type Load Cells and Hysteresis Considerations

S Type Load Cells are used in a wide range of applications, and the acceptable level of hysteresis varies depending on the specific application.

Industrial Weighing: In industrial weighing systems, such as platform scales or hopper scales, hysteresis needs to be relatively low to ensure accurate weighing. For example, in a food processing plant where ingredients are weighed for product formulation, a high – hysteresis load cell could lead to inconsistent product quality. Therefore, load cells with a hysteresis of less than 0.05% are often preferred in these applications.

Material Testing: In material testing machines, which are used to measure the mechanical properties of materials, hysteresis can affect the accuracy of force measurement. When testing the tensile or compressive strength of materials, a load cell with low hysteresis is essential to obtain reliable test results. Typically, in high – end material testing equipment, load cells with hysteresis values as low as 0.02% or even lower are used.

Robotics and Automation: In robotics and automation, S Type Load Cells are used to measure forces applied by robotic arms or grippers. Hysteresis can impact the precision of force control, which is crucial for tasks such as delicate object handling or assembly operations. In these applications, load cells with good hysteresis performance are necessary to ensure the smooth operation of the robotic systems.

Conclusion

As a supplier of S Type Load Cells, we understand the importance of hysteresis in ensuring the performance and accuracy of these devices. Hysteresis is a complex parameter that is affected by various factors, including material properties, strain gauge behavior, and mechanical design. By carefully controlling these factors during the manufacturing process, we can produce S Type Load Cells with low hysteresis, meeting the requirements of different applications.

Single Point Load Cell If you are looking for high – quality S Type Load Cells with excellent hysteresis performance, we are here to help. Our team of experts can provide you with detailed technical support and advice to ensure that you choose the right load cell for your specific application. Whether you are in the industrial weighing, material testing, or robotics field, we have the solutions to meet your needs. Contact us today to start a discussion about your load cell requirements and explore how we can work together to achieve your measurement goals.

References

ASTM E74 – 19 Standard Practice for Calibration of Force – Measuring Instruments for Verifying the Force Indication of Testing Machines.
ISO 376:2011 Metallic materials — Calibration of force – proving instruments used for the verification of uniaxial testing machines.
OIML R60:2012 Recommendations for Load Cells.

Huzhou Zhihe Technology Co., Ltd.
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