How Material Properties Affect Loss-in-Weight Feeder Performance

A loss-in-weight feeder is designed to deliver materials with high accuracy, but its performance depends greatly on the physical properties of the material being processed. Different powders, granules, or blends behave differently inside the hopper and screw. Understanding these material characteristics helps ensure stable and reliable feeding. Below are several key factors that explain how material properties influence loss-in-weight feeder performance.

1. Flowability

Flowability is one of the most important factors affecting feeding stability. Free-flowing granular materials move smoothly into the screw and typically provide more consistent output. However, fine powders, sticky materials, or products that tend to form clumps often cause bridging, rat-holing, or irregular flow. These issues can lead to fluctuations in the feed rate. Choosing the right agitation system, vibration assistance, or screw profile can significantly improve flowability and accuracy.

2. Bulk Density

Bulk density influences how well a material fills the screw. High-density materials usually offer stable feeding because they fill the screw consistently. In contrast, low-density or fluffy materials—such as lightweight powders—may trap air and cause sudden surges or slowdowns, resulting in unstable dosing. Selecting the appropriate screw diameter and optimal screw speed based on density is crucial for maintaining smooth output.

3. Particle Size and Shape

Particle characteristics determine how material behaves inside the hopper. Round and uniform particles flow steadily, while irregular or flaky particles may interlock and restrict movement. Fibrous materials can even wrap around the screw, causing jamming or inconsistent feeding. For these reasons, different particle shapes may require different screw types, such as single screws, twin screws, or customized designs.

4. Moisture Content and Surface Properties

Moisture significantly affects the behavior of materials. Wet or slightly sticky powders tend to adhere to the hopper walls or screw surfaces, making weight changes harder to track and causing inaccurate feed rates. Moist materials may also compact at the hopper bottom and block material flow. Keeping the environment dry or using hoppers with polished surfaces can help minimize sticking issues.

5. Compressibility and Aeration

Highly compressible materials tend to compact inside the hopper, reducing flow speed and causing inconsistent discharge. Conversely, aeration-prone materials, such as fine lightweight powders, expand when agitated and can suddenly accelerate through the screw. Both conditions disrupt the stability of the loss-in-weight feeder. Proper hopper geometry, venting, and controlled refill can help reduce these effects.

Material properties play a decisive role in the performance of a loss-in-weight feeding system. Factors such as flowability, bulk density, particle shape, moisture content, and compressibility directly influence feeding consistency and accuracy. By understanding these characteristics and selecting the proper screw type, hopper design, and auxiliary equipment, operators can significantly improve process stability and achieve optimal feeder performance.