In modern industry, scientific research, and daily life, as a key device for accurately measuring the weight of objects, the stability and accuracy of the performance of weighing sensors are crucial. However, a phenomenon called "hysteresis" often occurs during the use of weighing sensors, where there is a deviation between the output values of the sensor during the forward (loading) and reverse (unloading) processes. This deviation not only affects the accuracy of measurement, but may also cause difficulties in industrial automation control and data recording. This article will delve into the main factors that affect the hysteresis of weighing sensors and provide you with some practical insights.
1、 The basic concept of hysteresis
Hysteresis, also known as return error or hysteresis, is an important characteristic parameter of weighing sensors. It manifests as the input-output characteristic curves of the sensor not overlapping during forward loading and reverse unloading processes. This misalignment results in inconsistent measurement results of the sensor during forward and reverse loading, thereby affecting the accuracy of the measurement. Hysteresis is usually measured by hysteresis error, which is the ratio of the maximum hysteresis difference of the sensor over the full range to the output over the full range.
2、 The main factors affecting the hysteresis of weighing sensors
raw material
Elastic material: Elastic material is a key component of weighing sensors, and its stability, uniformity, and metallographic structure after heat treatment directly affect hysteresis. The ability of elastic materials to recover from microstrain determines whether the loading and unloading curves coincide. Selecting suitable metal materials, such as 40CrNiMoA, and improving the elastic limit through advanced heat treatment processes can help reduce hysteresis.
Strain gauge material: The strain gauge consists of a sensitive grid, substrate, coating layer, and lead wire, etc. It converts the strain of the elastic body into a change in resistance value through the resistance strain effect. If the strain gauge material itself has hysteresis, the overall hysteresis of the sensor will also be affected. Therefore, selecting strain gauge materials with low hysteresis and taking self compensation measures is the key to reducing sensor hysteresis.
Sealing adhesive material: Sealing adhesive is used in the production process of weighing sensors to fix the circuit and seal, preventing the influence of external environment on sensor performance. Although the strength of sealant is relatively low, its impact cannot be ignored in small range force measurement situations. Choosing the appropriate sealant material to ensure that the hardness and elasticity after curing match the sensor can help reduce hysteresis.
Installation conditions
Surface condition: The quality of the contact surface between the weighing platform and the sensor, such as roughness and parallelism, has a significant impact on the hysteresis of the sensor. Excessive surface roughness or insufficient parallelism can cause the fastening bolts to loosen, thereby affecting the accuracy of the sensor. Therefore, when installing sensors, it is necessary to ensure the flatness and cleanliness of the scale surface to reduce hysteresis.
Contact area: The fixed contact area between the sensor and the scale platform can also affect hysteresis. Install according to the installation conditions defined in the weighing sensor manual, ensuring sufficient and uniform contact area, which helps improve the stability and accuracy of the sensor.
Installation torque and bolt strength: Installation torque and bolt strength are important factors affecting sensor hysteresis. The greater the installation torque, the smaller the hysteresis; Insufficient bolt strength can lead to loose locking force, which in turn affects accuracy. Therefore, when installing sensors, it is necessary to strictly follow the manufacturer's installation and use instructions to ensure that the installation torque and bolt strength meet the requirements.
3、 Methods to reduce the hysteresis of weighing sensors
Optimize raw material selection: Choose elastic materials with good stability and high uniformity, as well as strain gauge materials and sealant materials with low hysteresis.
Improved heat treatment process: By using advanced heat treatment techniques, the elastic limit of the elastomer is increased, reducing the differences in the recovery process of microstrain.
Improve installation conditions: Ensure the flatness and cleanliness of the weighing platform surface, install sensors according to the instructions, and ensure sufficient and uniform contact area.
Strengthen maintenance: Regularly inspect the installation status and usage environment of sensors, promptly identify and address potential issues, and ensure the long-term stability and accuracy of sensors.
In summary, the hysteresis of weighing sensors is the result of multiple factors working together. By optimizing raw material selection, improving heat treatment processes, enhancing installation conditions, and strengthening maintenance measures, we can effectively reduce hysteresis and improve the measurement accuracy and stability of sensors. This is of great significance for industrial automation control, scientific research experiments, and weight measurement in daily life.
Source: Sensor Expert Network