Introduction
The Online Thickness Measurement System is the critical quality control hub for a high-performance 3-layer Stretch Film Making Machine. As extrusion speeds increase, manual thickness control becomes insufficient. This system provides a sophisticated, fully automated solution to ensure micron-level precision, consistent cling properties, and optimal load retention across the entire film web.
Advanced Sensor Technology
The system utilizes non-contact, high-speed scanning frames equipped with industry-leading sensors to deliver real-time data:
- X-Ray or Infrared (IR) Gauges: Depending on the material composition, these sensors provide non-destructive measurement. IR sensors are particularly effective for identifying individual layer distribution in 3-layer co-extrusion.
- High-Resolution Profiling: The sensor traverses the film web continuously, generating a high-definition "map" of the thickness profile, detecting even the slightest gauge bands or streaks.
- Rapid Sampling Rate: High-frequency data acquisition ensures that even at high line speeds, no deviation goes undetected.
Automatic Closed-Loop Feedback Control
The core advantage of this system is its ability to turn data into action. It creates a seamless communication loop between the measurement unit and the Stretch Film Making Machine's control center:
- Automatic Die Bolt Control: The system interfaces with the automatic profile die. By controlling the heating elements on the die bolts, it adjusts the thermal expansion of the die lip to micro-manage the gap at specific points.
- Extrusion Throughput Regulation: It synchronizes with the gravimetric dosing system and extruder screw speeds. If the overall average thickness drifts, the system automatically compensates by adjusting the extrusion output.
- Self-Correcting Mechanism: The software compensates for variables such as melt temperature fluctuations, resin viscosity changes, and ambient factory conditions without operator manual input.
Key Performance Benefits
- Material Savings & ROI: By tightening the thickness tolerance (reducing the CV% value), the system allows the machine to run closer to the lower limit of the specification. This typically results in 3% to 5% savings in raw material (LLDPE/PE).
- Superior Roll Geometry: Eliminates "thick spots" that cause uneven winding and "high edges." This ensures perfectly flat, cylindrical rolls that perform flawlessly in high-speed automated wrapping machines.
- Reduced Start-up Scrap: The automated control reaches the target thickness profile significantly faster during job changes or cold starts, drastically reducing wasted film.
- Data Traceability: Provides comprehensive production reports and thickness histograms, essential for ISO quality standards and internal audits.
Technical Integration
Designed for the Industry 4.0 era, the system features:
- Ethernet/IP or Profinet Connectivity: Seamlessly integrates with the PLC of the Stretch Film Making Machine.
- Visual Interface: A dedicated HMI displays real-time 2D/3D thickness profiles, trend charts, and alarm logs for the production team.
