A loss-in-weight dosing system is an advanced feeding method that doses raw materials continuously and with high precision at a set flow rate or quantity. The system works by measuring the weight loss over time of the material in a hopper mounted on a weighing unit, so the actual dosed quantity is calculated directly from weighing data.
In loss-in-weight systems, the weight of the material in the hopper is monitored continuously by load cells. The PLC calculates the actual flow rate from the weight change per unit of time, compares it with the target set by the operator and adjusts the speed of the feeding element under PID control. This ensures stable, precise dosing throughout the process.
Operating Principle
When the system starts, the material in the hopper is dosed into the process. Since the weight on the weighing unit decreases continuously, the rate of decrease determines the dosed quantity. When the hopper reaches a minimum level, the system stops automatically or switches to refill mode. After refilling, it resumes dosing automatically following a short stabilization period.
Automation and Control
Loss-in-weight dosing systems are PLC-controlled and managed via an operator panel or SCADA system. Through the system you can easily monitor and adjust:
• Target flow rate and tolerance settings
• Automatic / manual operating modes
• Refill and dosing transitions
• Alarm and error monitoring
• Production and consumption reports
Advantages
• Very high dosing accuracy
• Continuous, stable feeding
• Minimal sensitivity to changes in material density and flow
• Suited to recipe-based operation
• High accuracy in process control
Applications
Loss-in-weight dosing systems are widely used in plastics, chemicals, food, pharmaceuticals and masterbatch production, in all processes that require powder and granular raw materials to be dosed in precise ratios.