Product selection principles for load cells and torque sensors

Weighing sensor Weighing sensor is a device that converts mass signal into measurable electrical signal output. Its performance largely determines the accuracy and stability of electronic weighing system, so it is called the heart of weighing system. 1. Selection of sensitivity Usually, within the linear range of the sensor, the higher the sensitivity, the better. Because only when the sensitivity is high, the output signal value corresponding to the measured value is relatively large, which is conducive to signal processing. However, when the sensitivity is too high, the overload capacity of the sensor is low, which affects the service life, and the external noise unrelated to the measured value will also be amplified by the amplification system, affecting the measurement accuracy. Therefore, it is required to select the appropriate sensitivity according to your own requirements. For example: if you ensure that there will be no overload during long-term use, you can choose a sensitivity of more than 1.5MV/V, and the weighing is within 30%~70% of the full scale. If overload loads are often generated and dynamic shocks are prone to occur, you need to select a range that exceeds the overload force, reduce the sensitivity of the sensor, and increase the overload capacity. For overload selection, you can contact our company's technical support, and our company's technical support will provide the appropriate sensitivity and range according to your requirements. 2. Stability Selection The ability of a sensor to maintain its performance after a period of use is called stability. In addition to its own structure, the factors that affect the long-term stability of the sensor are mainly the use environment. Therefore, in order to make the sensor have good stability, it must have strong environmental adaptability. Before selecting a sensor, its use environment should be investigated, and a suitable sensor should be selected according to the specific use environment, or appropriate measures should be taken to reduce the impact of the environment. At the same time, economic efficiency should be considered. The price of sensors used in special environments is more expensive than that of sensors used in general environments. The environment will have the following effects on weighing sensors: 1. High temperature environment causes the coating material of the sensor to melt, the solder joints to open, and the stress in the elastomer to undergo structural changes. Choose a high-temperature sensor. 2. The effect of open-air dust and humidity on the sensor causing a short circuit. Choose a moisture-proof sensor 3. In a highly corrosive environment, such as humidity and acidity, the elastomer of the sensor is damaged or short-circuited. Choose an anti-corrosion sensor, such as a stainless steel sensor. 4. The effect of electromagnetic fields on the sensor output disordered signals. Generally, sensors have this function and provide shielded wires. If the impact is too large, you can choose to use an aluminum box to fully enclose the multi-layer shielded wire and a shielded wire with a thicker shielding layer that is not easy to break through. 5. Special explosion-proof sensors must be used in flammable and explosive environments. Choose explosion-proof sensors or intrinsically safe sensors. The stability of the sensor has quantitative indicators. After the service life is exceeded, it should be recalibrated before use to determine whether the performance of the sensor has changed. In some occasions where the sensor is required to be used for a long time but cannot be easily replaced or calibrated, the stability requirements of the selected sensor are more stringent and must withstand the test of a long time. 3. Selection of accuracy Accuracy is an important performance indicator of the sensor, and it is an important link related to the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor only needs to meet the accuracy requirements of the entire measurement system, and it does not need to be selected too high. In this way, a relatively cheap and simple sensor can be selected from many sensors that meet the same measurement purpose. If the measurement purpose is qualitative analysis, a sensor with high repeatability accuracy can be selected, and it is not advisable to select a sensor with high absolute value accuracy; if it is for quantitative analysis and accurate measurement values ​​must be obtained, a sensor with an accuracy level that meets the requirements should be selected. Accuracy selection meets the following two conditions: 1. Meet the requirements of the instrument input. The output signal of the sensor must be greater than or equal to the input signal required by the instrument. 2. Meet the accuracy requirements of the entire electronic scale. An electronic scale is mainly composed of a scale body, a sensor, and an instrument. When selecting the accuracy of the sensor, the accuracy of the sensor should be slightly higher than the theoretical calculated value. 4. Selection of the number and range of sensors The number of sensors is selected based on the purpose of the electronic scale and the number of points that the scale body needs to support (the number of support points should be determined based on the principle of coinciding the geometric center of gravity of the scale body with the actual center of gravity). The selection of the sensor range can be determined based on a comprehensive evaluation of factors such as the maximum weighing value of the scale, the number of selected sensors, the deadweight of the scale body, the maximum possible eccentric load and dynamic load. According to experience, the sensor should generally work within 30%~70% of its range, but for scales with greater impact force, when selecting sensors, the sensor should generally work within 20%~30% of its range to ensure the safety and life of the sensor. If you need selection consultation, you can contact our sales staff and technical support, and they will give you a satisfactory answer.