Gravimetric Feeder (Gravimetric Screw Feeder / Gravimetric Loss-in-Weight Feeder)

Core Working Principle

1. Gravity Discharge: Materials flow downward from the hopper by gravity into the feeding mechanism (usually a screw, belt, or vibratory tray).
2. Real-Time Weight Monitoring: A high-precision load cell continuously measures the total weight of the hopper, materials, and feeder body in real time.
3. Loss-in-Weight Calculation: The control system calculates the rate of weight loss per unit time (i.e., actual mass flow rate).
4. Closed-Loop Feedback Control: The system compares the actual flow rate with the set target flow rate, and automatically adjusts the motor speed (of the screw/belt) to correct deviations. This ensures the material is fed at a constant, precise mass flow rate, regardless of changes in material density, particle size, or moisture content.

Key Features & Advantages

• High Feeding Accuracy: Achieves ±0.5%–±1% steady-state accuracy, far superior to volumetric feeders (±2%–±5%), critical for batching, compounding, and quality-critical processes.
• Gravity-Driven & Energy-Efficient: Relies on gravity for material flow, reducing energy consumption compared to force-fed systems; low motor power and simple transmission structure.
• Wide Material Compatibility: Handles free-flowing to moderately cohesive bulk solids, including powders (cement, flour, talc), granules (plastic pellets, grains), flakes (chemical flakes), and fine minerals.
• Stable & Continuous Feeding: Minimizes pulsation and material segregation; ensures uniform feeding for long-duration industrial operations.
• Easy Operation & Maintenance: Modular design, simple structure, easy cleaning, disassembly, and replacement of wearing parts; low maintenance costs.
• Compact & Space-Saving: Vertical or horizontal installation options, small footprint, adaptable to limited production spaces.

Main Components

• Hopper: Stores bulk materials, often with a massaging cone/agitator to prevent material bridging or arching.
• Feeding Mechanism: Screw (most common), belt, or vibratory tray; conveys materials to the discharge port.
• Load Cell System: High-precision weight sensor, measures real-time weight loss data.
• Variable Speed Motor & Drive: Adjusts feeding speed per control signals.
• Control Panel: PLC/HMI interface, sets target flow rate, displays real-time data (flow rate, weight, speed), and enables parameter adjustment and fault alarm.
• Discharge Chute: Guides materials to the next process unit.

Typical Industrial Applications

• Building Materials: Cement, lime, gypsum powder, sand, gravel dosing.
• Chemical Industry: Resin pellets, pigments, fillers, chemical powders/granules.
• Food & Beverage: Flour, sugar, salt, grains, food additives.
• Plastics & Rubber: Plastic pellets, masterbatch, rubber powder.
• Pharmaceuticals: Pharmaceutical powders, granules, excipients.
• Metallurgy & Mining: Ore powder, coal powder, mineral fines.

VS. Volumetric Feeder