How does Loss in weight feeder work?
Loss-in-weight feeders from High Dream measure directly the weight of the material to maintain a predetermined feed rate. Due to the accurate metering performance and the excellent user-friendliness, twin screw loss in weight feeders are ideal for continuously feeding and metering powders and granular materials.
The feed rate of High Dream product is measured in kilograms per hour (e.g., kg/h). The operator programs the set point in the feeder control. Continuously weighing the hopper maintains a constant discharge of bulk material from the hopper, including the bulk material contained and adjusting the speed of the feeding device accordingly.
By comparing the actual loss rate of the double screw loss-in-weight feeder with the desired set point, precise adjustment can be achieved. When feeding with single screw feeders, solid materials with poor fluidity materials tend to bridge. This material builds up inside the outlet tube, causing fluctuations in the consistent output of the screw feeder. In such case, our ST 1 Twin screw loss-in-weight feeder with co-rotation will be the best choice. For more cohesive powders, twin screw feeders are often used due to their "self-wiping" effects, which minimize or even eliminate material buildup as well as help transport the material.
Since weighing determines the feeding accuracy, the feeder and the weighing unit must be isolated from external forces, friction, vibrations, or shocks. Typically, it is accomplished by flexible connections installed at the feeder inlet and outlet.
The feeders must be mounted on shock mounts, and air currents near the feeder must be minimized. The modern load cells which High Dream provides are the sophisticated methods for digital filtering applied by the weighing data to eliminate typical plant vibrations.
An error in feed rate may occur if the loss and weight feeder discharges material into an unstable pressure environment, such as a vacuum or pressurized conveying line. The pressure pulse exerts an upward force on the hopper outlet, slightly lifting and reducing the instantaneous weight of the hopper. The controller interprets this as too much material delivered and slows down the screw feeder, resulting in the feed rate is lower than desired.
On the contrary, a consistent positive pressure inside the hopper can also limit the weight loss detected. The controller interprets this as insufficient material being fed and speeds up the screw feeder, resulting in the actual material being overfed.
Twin screw loss-in-weight feeders of High dream, can automatically to adjust weight signals and the changes in pressure within a feeder. Consequently, the feeder control can compensate for pressure changes and regulate more accurately the feed rate.