A Swiss meat-processing plant uses non-contact ultrasonic presence sensing to increase productivity and eliminate breakdowns when washing empty meat bins. A single ultrasonic sensor, mounted above the conveyor on which the bins travel, checks for meat residues, rejecting any contaminated bins before the wash station. Old, contact-based systems were unreliable, resulting in breakdowns and frequent interruptions to the washing process.
- Improved sensor reliability derived from exact characterization of target
- Increased productivity arising from elimination of breakdowns
- Reduced sensor maintenance resulting from non-contact operation
- Industry-standard interface requires little modification to control systems
- Characterized sensors detect targets of variable size and shape
- Long-distance, non-contact operating principles
- IP65 protection allows operation in hygienic environments
- Rugged ultrasonic sensor with metal housing and metal cable connector
During production, an industrial meat-processing company conveys meat portions around its factory in food-grade plastic bins. After completion of each batch, empty bins are washed prior to reuse. Some bins contain sizeable pieces of meat which, if undetected, accumulate in the washing machine, causing blockages and breakdowns. The resulting interruptions to production are unacceptably frequent.A reliable sensor system must detect the presence of meat residues in bins as they travel along the conveyor. The sensor should identify all non-trivial residues and divert contaminated bins before they enter the washing station. The system should require little or no regular maintenance, and a non-contact sensor, suitable for a hygienic environment, is preferred.Old systems with spring-loaded wand-actuators in contact with the box are unreliable and require regular adjustment; the contact probes need frequent, time-consuming cleaning. The new system has to operate on a fit-and-forget basis.
Contrinex ultrasonic sensors are ideal for presence- and level-sensing applications, and a diffuse sensor from the Compact range (housing size M30) is an excellent choice for this application. Operating range for this metal-bodied, IP65-rated device is between 20cm and 130cm; detection is independent of the target’s color, shape, material or surface structure. Contrinex Compact ultrasonic sensors feature an integral S12 cable connector, allowing rapid disconnection and removal when required.The variable size and shape of meat residue makes it difficult for an uncompensated sensor to detect contamination consistently and reliably; potentiometer adjustment, provided by many manufacturers, is inadequate for this application. Contrinex CONPROG software for Windows®, connected via the APE-0000-001 PC interface, compensates perfectly.Using CONPROG, the operator characterizes the target area of the box during set-up, setting the exact operating parameters of the sensor and ensuring reliable detection. Sensor data is stored, allowing like-for-like sensor replacement without additional set-up.The sensor’s three-wire PNP normally-open output communicates directly with the customer PLC. On detection of a contaminated box, a mechanical diverter shunts the box to a separate conveyor for manual emptying.