Tunnel Type Metal Detector: Ensuring Product Purity and Safety

Tunnel type metal detectors represent a critical component in modern industrial processes, designed to safeguard product quality and ensure consumer safety by identifying and rejecting metallic contaminants. These sophisticated systems operate as a closed circuit, meticulously scanning products as they pass through a detection tunnel. The core principle relies on generating an electromagnetic field which, when disturbed by the presence of metal, triggers an alarm and rejection mechanism.

The efficacy of a tunnel type metal detector is significantly influenced by several factors. Crucially, the detection sensitivity within the inner center of the tunnel is directly dependent on its dimensions. As the inner length of the tunnel increases, the sensitivity of metal detection inherently decreases, and conversely, as the tunnel dimensions become smaller, the sensitivity for metal detection increases. This inverse relationship underscores the importance of selecting a detector with appropriate tunnel dimensions tailored to the specific product and desired sensitivity levels.

Furthermore, the physical environment and the product itself can introduce challenges. The “product effect,” for instance, refers to the inherent conductivity or magnetic properties of the product being inspected, which can disadvantageously impact sensitivity. Negative environmental factors such as magnetic parasites (external electromagnetic interference) and vibrations can also compromise detection accuracy in tunnel-type metal detectors. To mitigate these issues, it is imperative that the conveyor belt used with the metal detector is vibration-free, antistatic, and consistently clean to prevent false positives and maintain optimal performance. Where heightened sensitivity is paramount, more sensitive sensing configurations are recommended to ensure even the smallest metallic intrusions are identified.

Advanced Design and Operation

These detectors are engineered for seamless integration into existing production lines, offering robust performance and reliability. Their advanced electronic systems are capable of detecting a wide range of metallic contaminants, including ferrous, non-ferrous, and even difficult-to-detect non-magnetic stainless steels, depending on the model and sensitivity settings. The user interface is designed for ease of operation, allowing for precise control and monitoring of the detection process.

Key Advantages and Applications

Implementing tunnel type metal detectors brings a multitude of benefits to manufacturers. They play a vital role in preventing product recalls, protecting brand reputation, and ensuring compliance with stringent industry standards such as HACCP, BRC, and IFS. These systems are indispensable across various sectors, including:

• Food Processing: From baked goods and confectionery to meat, poultry, dairy, and produce, ensuring food safety and preventing consumer injury.
• Pharmaceuticals: Safeguarding the integrity of medications and health supplements.
• Textiles: Detecting needles, clips, or broken machine parts to protect both products and consumers.
• Plastics and Recycling: Preventing damage to machinery and improving the quality of recycled materials.
• Chemicals and Mining: Protecting processing equipment from metallic foreign objects.

The robust construction and intelligent software ensure high throughput without compromising detection accuracy, making them an essential investment for quality assurance.

Detailed Technical Specifications

Our tunnel type metal detectors are built with precision and incorporate advanced features to deliver superior performance and reliability in demanding industrial environments. The specifications below highlight the robust engineering and user-friendly functionalities integrated into each unit:

Technical Specifications:

• 2 x 1 mm LIYCY cables, LCD digital display, Sensitivity setting by numerical value, Wait and delay time, Automatic and manual reset setting, 2 metal relays and 1 fault relay, Interference setting, Product reset and counting, Rivet sensor connectivity before or after
• Excitation relay : 6 Amp Inverter Fault relay : 6 Amp Inverter. Dashboard : IP 65
• Metal dimensions to be detected: ≥ 30 mm Ambient operating temperature : -20 ºC / +40 ºC
• Voltage : 220±10% 50Hz Recommended Feed Belt Speed: 1.49-1.07 m/s

These specifications ensure comprehensive control and robust operation. The 2 x 1 mm LIYCY cables provide durable and reliable electrical connectivity, while the LCD digital display offers a clear, intuitive interface for operators. Numerical sensitivity settings allow for precise calibration tailored to specific product requirements, optimizing detection without excessive false alarms. Features like “Wait and delay time” along with “Automatic and manual reset” provide flexibility in integrating the detector into varied production line sequences and recovery protocols. The inclusion of two metal relays for detection and one fault relay for system diagnostics, all rated at 6 Amp Inverter, ensures reliable signaling and robust system feedback. An IP 65-rated dashboard signifies high protection against dust and water ingress, enhancing durability in harsh industrial settings. The interference setting is crucial for filtering out environmental electromagnetic noise, thereby increasing detection accuracy. Product reset and counting functions aid in production monitoring and quality control. The option for rivet sensor connectivity before or after the detector allows for specialized applications where fasteners or other known metal components need to be accounted for in the detection process.

The “Metal dimensions to be detected: ≥ 30 mm” indicates the minimum reliable detection size for certain applications, suggesting that objects of 30mm or larger will be consistently detected. For applications requiring detection of smaller contaminants, specialized configurations or higher sensitivity models may be required. The wide ambient operating temperature range of -20 ºC to +40 ºC ensures reliable performance in diverse climates. Operating on a standard 220±10% 50Hz voltage, these units are compatible with common industrial power supplies. The recommended feed belt speed range of 1.49-1.07 m/s helps maintain optimal product separation and stable detection performance.

Conclusion

Tunnel type metal detectors are an indispensable asset for any manufacturing operation committed to quality, safety, and operational efficiency. By providing reliable detection of metallic contaminants, they protect consumers, prevent costly recalls, and uphold brand integrity. Their robust design, advanced technical features, and adaptability make them a cornerstone of modern industrial quality control strategies.

Please contact us for detailed information.