The steps involved in manufacturing a strain gauge based load cell include:
Machining complex patterns to optimize stress and strain on mechanical members, controlling surface roughness through surface polishing to ensure that rough edges are removed before bonding strain gauges, scoring alignment marks to align multiple strain gauges that need bonding to create Wheatstone Bridges, adhesadheses with matching temperature coefficients applied to the metal used, Applying uniform pressure to the strain gauge during curing to avoid clumping along the key, curing at high temperatures in an oven to solidify the adhesive and regulate the bond, applying coatings to protect the strain gauge and wiring from wet and humid environments, and once the sensor is built, it needs to be tested at different temperatures to determine temperature drift. Install a thermistor to reduce the temperature impact at zero load, then perform a full scale load before final testing and calibration. As you can see, resistive load cells are cumbersome to build and require many manual steps in the manufacturing process.
However, if built correctly with a reliable signal source, a resistive load cell built with a bonded foil strain gauge can achieve an accuracy of +/ -0.02% of full scale, just like our RSP1 load cell! And, when the temperature change is properly compensated, they can be used between -10 ° C and 40 ° C and usually have very good resistance to temperature change. Finally, these load sensors provide excellent eccentric load compensation and are therefore very useful for building scales where the measured weight can be randomly placed anywhere on the loading platform.
