Load cell manufacturing process

The metal resistance strain gauge is pasted on the metal weighing beam inside the load cell to convert the physical deformation of the resistance strain gauge into an electrical signal that can be measured and read. The metal resistance strain gauge is composed of a measuring bridge, which is made of the effect that the metal resistance wire is stretched and thinned under tension, and the resistance increases or decreases, that is, the metal resistance changes with the strain. Now let's learn about the manufacturing process of the load cell.

1: Main process steps

Patch → bridge assembly → compensation → test → protection

2: Brief description of the placement process

The patch is a process that uses adhesive to stick the strain gauge on the elastomer, and through certain conditions (such as temperature rise and pressure), the elastomer and the strain gauge are closely combined, so as to transfer the stress and strain of the elastomer by the strain gauge. Patch is a key process in the whole sensor manufacturing process (except for mechanical processing). The quality of the patch directly determines the performance of a sensor, and directly affects the zero point, zero compensation, hysteresis, creep, repeatability, stability and other key indicators of the sensor.

3: Brief description of bridge formation process

Bridge formation is the process of connecting strain gauges into a Wheatstone bridge according to certain requirements. Bridge assembly is composed of welding spot polishing and tin hanging, welding wire preparation, bridge circuit connection and other steps.

4: Brief description of compensation process

Compensation refers to the correction of the zero point output and full range output of the sensor at the end of the bridge group.

4.1: Correction of zero point output

When the sensor is used in the weighing system, it should be used together with the instrument, so its zero position should be corrected to a certain range, otherwise it will increase the error of the entire testing system. At the same time, because the ambient temperature will change when the sensor is used, and the zero output will also change with time and temperature, it is necessary to compensate the sensor zero point in production to reduce the change caused by the environmental impact after it is applied to the system to the error range that meets the use requirements.

4.2: Correction of full scale

When the sensor is used, because the material is affected by the change of ambient temperature, its elastic modulus decreases when the temperature rises, making the full range output larger; When the temperature decreases, the elastic modulus increases, making the full range smaller. However, the change of the full range with the change of the output temperature often exceeds the allowable error range of the sensor, so it is necessary to correct this phenomenon, that is, the correction of the full range, also known as temperature sensitivity compensation. In general, the compensation for temperature sensitivity has been modified according to certain parameters when designing the product, and has been added into the circuit bridge.