In fully electric plastic injection moulding machines, Baumer load cells measure injection, back and dwell pressure at the dosing screw. They provide precise and reproducible values over the entire process. In case of deviations from the preset parameters, the control regulates the acting force. This is crucial for the quality of the parts to be moulded.
A strain gauge is a simple electrical resistance. Just like any other resistance, a strain gauge is defined in its resistance value by the length and width of the conductor. Correspondingly, the following applies:
- the longer the conductor, the higher the resistance value
- the thinner the conductor, the higher the resistance value
When mechanical stress is applied to the strain gauge by means of tension, pressure, deflection or torsion, its electrical resistance value changes. This physical behaviour is utilised in force measurement by creating a frictional connection between the strain gauges and the measuring element. To achieve this, the strain gauges are glued to the measuring element with a special adhesive. This results in the distension of the measuring element, which also causes strain and thus a change in resistance in the strain gauge by means of traction. Then the change in resistance is measured and electronically amplified. It is a measure for the force acting on the measuring element.