Checkweigher

A checkweigher is a precision weighing system integrated into packaging production lines for packaged food products. It automatically verifies the weight of individual packages against predetermined specifications, ensuring compliance with regulatory requirements and minimizing product giveaway. The device is typically installed inline, after filling and sealing, to inspect every package at full production speed. It uses load cells or strain gauge sensors to measure the weight of packages as they pass through the conveyor system. The measured weight is compared against preset tolerance ranges, and a rejection mechanism removes underweight or overweight packages from the line. This helps maintain product quality, reduce waste, and meet legal metrology requirements. The checkweigher is a component of the packaging line, not a standalone machine, and must be integrated with the existing conveyor and control systems. It is commonly used in food manufacturing, where hygiene and washdown capability are important. The equipment is typically constructed from stainless steel and aluminum alloy, with electronic components for control and data processing. Key parameters include a weighing range of 5–1000 g, accuracy of ±0.1–±0.5 g (per OIML R51), throughput of 60–300 packages per minute, belt speed of 30–120 m/min, conveyor width of 200–600 mm, power supply of 220 V AC ±10%, operating temperature of -10 to 40 °C, ingress protection of IP54–IP65 (per IEC 60529), frame material of 304–316 stainless steel (per ASTM A240), and machine weight of 80–200 kg. These values are typical ranges for food packaging applications and must be confirmed for the specific model and application. The checkweigher is not a legal measuring instrument unless certified; compliance with standards such as OIML R51 must be verified with the manufacturer. Always consult the supplier for model-specific specifications and validation.

The checkweigher operates by continuously weighing packages as they move along a conveyor. Load cells or strain gauge sensors generate an electrical signal proportional to the weight. The signal is processed by a control unit that compares the measured weight to preset upper and lower tolerance limits. If a package falls outside the acceptable range, a rejection device (such as a pusher or air jet) is activated to remove it from the line. The system can be calibrated and adjusted for different product weights and tolerances. The accuracy is influenced by belt speed, vibration, and environmental conditions. Regular calibration and maintenance are necessary to ensure reliable operation.