Conventional strain sensors are based on strain gage technology. In order to effectively measure the strain values in a force or load measurement application, a full, 4 element strain gage bridge circuit is utilized. The configuration is known as a Wheatstone Bridge Circuit. A Wheatstone Bridge has a very linear output in it’s midrange. That being considered +100% to -100% of range. Unfortunately, a Wheatstone Bridge becomes non-linear above the upper and lower extremes of range. Therefore, significant errors can result above the end points when attempting to take precision measurements. It is particularly important to take accurate measurements in some R&D or control applications. To avoid the mentioned error issues, PCB manufactures quartz and piezoelectric strain sensors that output the same mV/microstrain sensitivity throughout the entire useful range. Thus, accuracy is improved and control requirements are enhanced that may occur at positive extremes of the measurement range. The models RHM240 and model 740B02 series sensors are the strain sensors for these applications.
ICP® Strain Sensors For Process Monitoring/Quality Control
The Series M240 Industrial ICP® Strain Sensors incorporate piezoelectric quartz sensing crystals that respond to a longitudinal change in distance. The resultant strain measurand is an indirect measurement of stress forces acting along the structure to which the sensor is mounted. As such, these devices can provide insight into the behavior of mechanical systems or processes that generate an associated machinery reaction.
Monitoring such measurement signals can provide the necessary indication for process interrupt and pass/fail decisions or for determining wear and degradation of equipment and tooling. The sensors are used for controlling processes in plastic injection molding, spot welding, stamping, and pressing, as well as monitoring processes and final product quality. These devices are easy to install and can be powered by any ICP® sensor signal conditioner such as our DIN rail module 410B01.
In additional to providing ICP® power, the 410B01 serves as an interface between sensor and machine control. Features such as independent peak and continuous outputs, gain, and selection of AC/DC coupling make integration straight forward.