Loss-in-weight or
LOSS-IN-WEIGHT FEEDERS
Loss-in-weight screw feeders can be used continuously or intermittently. The screw feeder is mounted on load cells or scales that measure the total weight of the feeder and its contents. The screw feeder dispenses the material from a hopper at a controlled rate using an auger screw. While dispensing the material, the system continuously monitors the weight of the dispensing hopper, providing real-time feedback on the material being discharged and calculating the material loss rate (discharge rate) by monitoring the decrease in weight over time. The feedback control system plays a crucial role in this process, adjusting the rotational speed of the auger screw to maintain a constant feed rate based on the weight loss data and allowing for immediate adjustments to maintain the desired feed rate, ensuring precise control over the amount of each ingredient added.
GAIN-IN-WEIGHT FEEDERS
Like Loss-in-weight feeders, a gain-in-weight screw feeder can be used in continuous or intermitted operations, and operation principles are the same, an auger dispenses the material from a hopper. The key distinction lies in the positioning of the load cells or scales. In gain-in-weight screw feeders, the load cells or scales are located beneath the receiving vessel rather than being directly mounted on the feeder. As the feeder dispenses the material, the system weights the amount of material in the receiving vessel. A feedback control system adjusts the dispensing mechanism to achieve the desired weight of material dispensed.
APPLICATIONS
Loss-in-weight feeders are the preferred choice for applications involving the simultaneous addition of more than one ingredient into a receiving vessel. This preference stems from the design of the system, where the load cells are strategically located under the screw feeder. This configuration ensures that the dispensing calculations are based solely on the weight of the feeder and its contents. As a result, any additional material added to the receiving vessel from other sources does not interfere with the feeder’s discharge rate. The feeder operates independently, maintaining precise control over the amount of material it dispenses, regardless of other inputs.
In contrast, gain-in-weight feeders are better suited for applications that involve dispensing small amounts of material into a container, especially in processes where materials are added sequentially rather than simultaneously. In these systems, only the combined weight of the container and the material being added is measured. The control system is designed to handle sequential additions accurately, tracking the weight changes with each material added individually. However, gain-in-weight feeders may not be the best choice when it comes to handling simultaneous material additions. The weighing system of these feeders can struggle to calculate the dispensing rate accurately in such scenarios. This is because the system cannot differentiate between the weights of materials dispensed from various sources. As a result, simultaneous additions can lead to inaccuracies, making gain-in-weight feeders less suitable for such scenarios.