The gauge rollers form the dough into a flat sheet of the required thickness in a continuous process before the biscuit shapes are cut out prior to the baking process. The dough sheet thickness control is not only important for consistent quality and material costs but also needs to facilitate different product to be produced, so fast changeover times are important. The previous sensor, an older LVDT type, required a special electronics module to convert its signal to suit the machine’s PLC and all components needed a good deal of electrical calibration to compensate for the nonlinearity of the electrical response before changeover. Furthermore, a relatively long overall length and large diameter for the previous LVDT sensor made the gauge roller assembly somewhat bulky.

Positek’s P103 series short stroke linear position sensor with LIPS® technology is ready-calibrated to the exact travel required so can be directly installed into the machine for each set of paired gauge rollers with no need for extensive and costly setup. Positek’s LIPS® technology is based on inductive coils and uses a unique custom integrated circuit to produce an accurate analogue output signal. Its standard two-wire 4-20mA output directly interfaces with the PLC and greatly simplifies the previous wiring arrangement. With a linear response to within ± 0.25% of the travel range and extremely low temperature coefficient error, the sensor has improved the accuracy and long-term signal reliability resulting in reduced machine recalibration and maintenance requirements. With no need to incorporate adjustments in the PLC, installation and commissioning is now faster and less complicated. The sensor’s mounting flange face provides convenient mechanical interfacing and is used as the reference for factory calibration, so when installed on the machine the only adjustment required is setting an initial mechanical datum for the roller gap using a Vernier gauge screw. The P103’s housing diameter is just 35 mm and, with the output calibrated to the measurement travel required, the short-stroke linear position sensor’s nominal length remains compact with no unwieldly overhanging components for the gauge roller assembly. Its stainless steel construction and IP65 sealing (IP67 on request) and wide operating temperature range of – 40 to +125 °C is a perfect fit for food and beverage applications.

The P103 series is generally available with spring loaded or a free running plunger and is part of a wide range of linear, rotary and tilt sensors utilising Positek’s LIPS® technology which is characterised by excellent EMC, vibration, shock and environmental specifications. The comprehensive range includes ATEX, IECEx, and CSA certification across many product lines with wide use in intrinsically safe, hazardous, automotive, and submersible measurement tasks as well as general industrial and scientific applications. Through the range optional voltage and current output alternatives are available along with custom electrical and mechanical modifications. Positek Ltd is an ISO9001:2015 certified designer and manufacturer and part of the Variohm Group of companies.