Gravimetric Feeder Gets Boost from New High-Speed Stepper-Motor Drive

The Maguire MGF gravimetric feeder for metering colorants and additives into plastics processing machines now provides greater accuracy and up to double the throughput.

Test data available from Maguire comparing the enhanced MGF unit with the leading competitive gravimetric feeder indicate that when each was equipped with a half-inch auger, the Maguire device provided a wider throughput range, 0.4 to 120 lb/hr, as opposed to 1.5 to 55 lb/hr. Dosing accuracy was also greater. In tests involving 100 dispense cycles with a target of 11 g per dose, the MGF average was exactly 11.1 g, versus 11.3—a 1.8% variance for the competing feeder

Maguire achieved this boost in performance by replacing the continuous-rotation electric motor used for driving the feed auger with a stepper motor that completes each rotation in 200 increments and at a maximum speed of 100 rpm. In combination with digital control, the 200-step cycle achieves finer resolution in metering ingredients into the molding or extrusion process.

The high motor speed makes possible a doubling of throughput to 120 lb/hr in extrusion and up to 40 lb/hr in cyclical processes like injection molding. The throughput range for a given auger size has also increased, reducing or eliminating need for auger changes.

“The finer resolution made possible by the stepper motor adds to the intrinsically greater accuracy of our gravimetric feeder in comparison with volumetric devices, increasing the ability of molders and extrusion processors to reduce color and additive consumption, better control product quality, and document color usage,” said B. Patrick (Pat) Smith, vice president of marketing and sales. “These improvements come at no added cost to customers, who can still purchase our MGF feeder at the same price as our volumetric system and for 35% less than competing gravimetric devices.”

Maguire has sold more than 800 units of the MGF feeder worldwide and offers the system with a five-year warranty.

For more information, visit www.maguire.com.