EXTRUSION: First Gearless Melt Pump

Unit relies on counter-rotating intermeshing twin screws.

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Henschel America Inc., Green Bay, Wis., has developed a new type of “gear” pump that actually uses no gears at all. Instead, the Xtreamor melt pump relies on counter-rotating, intermeshing twin screws to generate pressure from a single- or twin-screw extruder to the die. Compared with gear pumps, this unit is said to require dramatically less inlet pressure (0-1 bar) while lowering energy consumption.

Conventional gear pumps rely on the molten plastic to lubricate their bearings. Henschel says this causes problems when running high levels of fillers or abrasive materials. The Xreamor pump reportedly can run LLDPE filled with 85% calcium carbonate, as well as glass fiber or beads and virtually any kind of dirt in recycled products, without “de-mixing” the material or destroying glass strands or beads. The Xtreamor is said to cut extruder energy usage by as much as 50% because the extruder can run at lower melt temperatures and does not have to generate pressure. This, in turn, is said to extend the life of the extruder wear components.

The Xtreamor is equipped with both heating coils and cooling units. This is also said to differentiate it from standard gear pumps, which in most cases just heat the material. It is said to be extremely easy to clean via purging without the need for disassembly. Screws are available in different designs and can be tailored to the application.

Two sizes are now available: the HMP 2-100, which can run at least 660 lb/hr; and the HMP 2-140 for 4000 lb/hr or more. A lab-sized unit and a much larger pump with capacity up to 30,000 lb/hr are in development.