Low-cost liquid color pump offers increased accuracy, ease of operation, lower maintenance

09-Dec-14

A liquid color pump of completely new design costs 35% less than existing equipment yet meters color more accurately into the molding or extrusion process, simplifies job startups and color changes, and requires minimal maintenance, it was announced today by Maguire Products, Inc. Compared with standard volumetric pumps, the patent-pending PeriStep™ pump provides 20% greater accuracy in dosing liquid color directly into the main flow of natural resin, and it includes a self-adjusting automatic speed control that maintains dosing consistency. Setting the control for startup involves a simple, intuitive three-step process. For color changes, the operator merely retracts the top cover of the pump and lays a new tube over the rollers inside, without need of working the tube into a compression zone. Tubing is reusable for up to six months and is available in three sizes to accommodate a range of dosing outputs. Two innovations (U.S. patent application 62/025) are key to the low cost, accuracy, and simplicity of the PeriStep liquid color pump. Instead of a standard motor, the drive system is a stepper motor whose shaft rotates in discrete, minute increments that make possible precision and repeatability of movement. This motor drives a central “sun” roller, whose motion transfers to the “planetary” rollers that provide the compression / relaxation cycle of a peristaltic pump. Maguire has reduced the number of planetary rollers to four from the conventional six. The sun roller drives the planetary rollers by means of friction contact, providing a 5 to 1 speed reduction without a gear box. “The compact, streamlined design of the PeriStep pump lends itself to minimal maintenance, since there are no gears or bearings to wear out,” said Steve Maguire, president of Maguire Products. “If it does become necessary to disassemble the pump, access to the roller set involves simply removing three screws in the cover.” The process for setting up a job in the controller of the PeriStep pump involves only three digital inputs: 1) shot weight (for injection molding) or extrusion rate; 2) liquid color percentage; and 3) density of the liquid color. The controller automatically calculates the desired weight-to-volume dose, minimizing the opportunity for error.