Processors using liquid colors and additives can now reportedly benefit from the accuracy and simplicity of gravimetric metering technology by virtue of the TrueFeed LQ liquid feeder from Conair, Cranberry Township, Pa. The liquid feeders eliminate the need for time-consuming color calibration and adjust automatically for changes in material and processing conditions. This results in easier set-up and greater processing uptime.
The feeders use the same clean, simple peristaltic pumping technology as conventional volumetric dosers. However, the liquid container is supported on a load cell that constantly measures the loss in weight as material is pumped to the processing machine. Programming is described as easy. In injection molding, the operator enters the part weight and the color/additive percentage. For extrusion, the feeder can run on an open loop or control the metering rate against extruder screw speed. Once set up, the digital control takes over, adjusting pump speed to changes in production rate, viscosity, pump/hose condition, or environmental conditions.
The menu-driven control system stores up to 1500 process settings and tracks actual dosed weights, providing process validation over time. The weighing system has a self-regulating electronic filter that compensates for vibration.