Precision Melt Pumps

The GF series melt pumps, used for precision metering of fluoropolymers, are available either as part of a complete extrusion line or as upgrade packages for improving existing extrusion lines.

The output of an extruder used alone is highly variable, depending on changes in back pressure, viscosity of the plastic, percentage of regrind, and melt index of the polymer. Adding a melt pump stabilizes the throughput to the order of 0.1%. It makes the throughput of the system independent of external conditions. It also increases the output, typically by 15 - 20%.

A practical use of the new pumps is in a complete extrusion line with the extruder, and downstream equipment designed to take advantage of the greater throughput precision.

It allows use of integrated, closed loop control of final extrudate dimensions in lines using fluoropolymers, as well as the polymers. Harrel offers turnkey tubing lines for medical and similar applications, giving automated control of outside and inside diameter, as well as length. Bump tubing and multi-layer tubing lines are also available. In all cases, control of the resin usage to tolerances of 0.1 % is provided, controlling one of the main costs in any extrusion operation.

Complete retrofit packages are also available. Included are the melt pump, the drive motor and the gear reducer, which are mounted on an adjustable stand. The precision digital drive for the pump, temperature controllers, and control for integration with the extruder drive are mounted in a separate sloping front, floor mounted cabinet.

Harrel Inc., 16 Fitch St., E. Norwalk, CT 06855. Tel: 203-866-2573; Fax: 203-866-1483.