Parallel Twin Screw Extruder

Milacron's new small-footprint parallel twin screw extruder, the Atlas 93, is said to present powerful features for sheet extrusion line screen profile processing. Like the manufacturer's 114 and 135 models, which it complements, the Atlas 93 is reported to be ideal for generating PVC pipe also, siding, and sheet, in addition to for processing various foam applications.

The counter-rotating parallel screws of the Atlas 93 have a length-to-size ratio of 26:1 L/D (measured from the downstream end of the feed port), says Milacron. The feed zone provides "exceptional" surface, allowing efficient temperature transfer to the feed material. Further, the maker explains, a minimal compression ratio, distributed over an extended L/D ratio, decreases screw deflection and extends the life of both screws and barrels significantly.

All system features were created into a "unitized bottom," simplifying installation, operation, and maintenance, says Milacron. Simple "drop-in-place" machine installations and single electric drop requirements enable processors to come to be ready to go quickly, the ongoing company adds. Standard features reportedly include:

*High-capacity four-shaft gearbox (unlike almost every other parallel twins screw extruders, which use a three-shaft design) with integral casing containing both lowering and distribution gearing for higher torque and thrust capability;

*Metered dosing feeder for correct intake volume and wide processing latitude;

*Consistent, controllable process cooling and heating program featuring five barrel process zones with the 3 downstream zones using drinking water cooling--a design that's said to be "nearly maintenance free," compared with that of oil-cooled devices;

*Availability of microprocessor handles or discrete instrumentation at the same price;

*Subcomponents such as vacuum engine and pump, barrel cooling screw and system oil heating/cooling system installed on slide-out trays for easy maintenance;

*Direct-coupled Reliance AC vector electric motor and drive system for expanded service in PVC production;

*Milacron Exc microprocessor control, which "oversees" the extruder operation and provides a basic, all-inclusive control station.