Technology That Operates with Mass-Based Precision and Determines Production Performance

Gravimetric feeders are critical process equipment that ensure the precise, repeatable, mass-based feeding of raw materials in powder, granular, and pellet form. VOLDE gravimetric feeders are designed in accordance with both batch and continuous (Loss-in-Weight) operating principles, delivering high accuracy and long-term stability even with materials of differing flow behavior.

| Loss in Weight (LIW) Feeders

Loss-in-weight feeders continuously measure the weight of the feed hopper, calculate the instantaneous flow rate (kg/h) from the weight change over time, and dynamically adjust this value against the target set point. Thanks to this structure, the system operates not merely on speed but with true mass feedback, ensuring constant feeding throughout the process. It is the main piece of equipment determining process quality, particularly in extruder feeding, continuous mixers, and precision additive dosing applications.

In these systems, the control algorithm filters the load cell signal to eliminate high-frequency noise, optimizes the feed speed via PID control, and produces a stable feed curve even at low flow rates. Variations in material density, fluctuations in flow behavior, or mechanical effects have minimal impact on system performance.

_ Technical specifications and performance details:

• Real-time mass flow rate measurement and control (kg/h)
• High dosing accuracy in the range of ±0.25% – ±1%
• Dynamic speed adjustment via PID-controlled VFD drive
• Linear and stable feed characteristics across a wide operating range
• Stable performance even at low flow rates (micro-dosing)
• High-frequency load cell signal filtering and vibration compensation
• Automatic zeroing (tare) and calibration functions
• Real-time flow rate, total consumption, and trend monitoring via SCADA

| Refill Management and Continuity

The most critical issue in loss-in-weight feeders is refill management. By its nature, the system operates while the bin is emptying; during filling, the measurement is temporarily affected. For this reason, a properly designed LIW system must be able to continue operating without losing feed continuity during refill.

In VOLDE systems, the refill process is managed through automatic mode transitions and advanced control algorithms. When refill starts, the system briefly switches to volumetric mode, and once filling is complete, it returns to gravimetric mode to regain its precision. These transitions occur so smoothly that they go unnoticed by the operator.

_ Refill scenarios and system solutions:

• Automatic filling from an upper bin or silo (via vacuum / mechanical conveying)
• Semi-automatic filling via big-bag discharge or bag feeding
• Automatic refill triggering via low-level sensors
• Volumetric transition mode for uninterrupted feeding during refill
• Automatic stabilization after filling and return to gravimetric mode
• Adaptive control algorithms that minimize refill-related errors

| LIW Screw Feeders

Screw-type loss-in-weight feeders are optimized specifically for fine powders, additive materials, and low-flow-rate precision dosing applications. The screw geometry, pitch structure, and rotation speed are custom-designed according to the flow behavior of the material.

_ Key features:

• wide application range with single/twin screw options
• Stable feeding with fine, cohesive, and difficult-flowing powders
• High precision in micro-dosing applications
• Flow improvement supported by agitator and vibration
• Easy on-machine integration through compact design

| LIW Belt Feeders

Belt-type loss-in-weight feeders are preferred in applications where the product must be conveyed and dosed without mechanical damage. They are the most suitable solution particularly for fragile granules, pellets, flake-form materials, and processes where preserving product integrity is critical.

Compared to screw feeders, since they do not create shear or compaction effects on the product, particle form is preserved, segregation is prevented, and product quality is kept stable.

_ Technical specifications and advantages:

• Continuous gravimetric control via mass measurement on the belt
• Low-stress conveying and dosing without damaging the product
• Homogeneous product distribution via a wide belt surface
• High performance with low-density, bulky materials
• Low maintenance requirements and long mechanical life

| Batch-Type Gravimetric Feeders

Batch-operating gravimetric feeders feed material until a specified target weight (kg) is reached, then stop. They are particularly preferred in recipe-based production, mixer feeding applications, and processes requiring precise weighing.

Features:

• Automatic stop at the set target weight with high repeatability
• Recipe-based management of multiple raw materials
• Full process control via PLC & SCADA integration
• Precise results via coarse + fine feeding
• A structure adaptable to different capacities and bin volumes