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May 1, 2000

4 Min Read

Booth N-7171

npe43.jpgWhat's Hot! Maguire will have introductions in its various product lines, including new technology that is said to provide increased batch-to-batch blender accuracy in dispensing minor ingredients; the S-20 Shuttle Granulator, for reducing purgings and other heavy-duty scrap; and the WST 110 Weigh Scale Totalizer, a dispensing unit for pre-blended or single-component materials that can be mounted at the extruder throat.

Maguire says it has increased the batch-to-batch accuracy of minor-ingredient dispensing in its line of gravimetric blenders. Based on proprietary software, the innovation allows molders or extruders to dispense very small quantities of additives that vary in pellet geometry, bulk density or flow properties without compromising product quality or consistency.

The new blenders use a batch process and weigh each ingredient separately in order to control the levels of colors or additives. The operator sets the controls for the desired percentages of resin, regrind, color, and additive and the microprocessor automatically adjusts material dispensing to maintain the preset batch ratio. The controller verifies weight readings at high speeds and is said not to be affected by machine vibrations or other shocks. Blend accuracy over time is kept to within 0.01%, according to the company.

Using new error-correction logic, the blender controller recognizes even miniscule dispense errors that stem from material flow inconsistencies and corrects them in real time so that the blend ratio remains constant throughout production. While yielding exceedingly uniform products and reducing consumption of expensive minor ingredients, the new software does not compromise the blender's throughput capability.

The technology can be retrofitted at low cost to many installed Maguire gravimetric blenders through merely a chip change.

Also new at the show will be a smaller version of a heavy-duty granulator the company introduced last May (Jun '99 PA, p 27). The new S-20 Shuttle Granulator was developed for reducing purgings and other heavy-duty scrap with a smaller scrap containment chamber and a smaller footprint than the previously introduced S-30 model.

The scrap containment chamber measures 20 x 30 in. (versus 30 x 30 in. for the S-30) and the footprint is 51 x 72 x 50 in. Otherwise, the new unit operates in the same way as the older unit.

In the planning stage, purgings or reject parts are shuttled back and forth over a table surface that is split into two levels like a carpenter's plane. Mounted at the point of disjunction is a series of staggered rotor knives that turn at 1750 rpm, reducing the gravity-fed scrap to small pieces and propelling them into the hopper of a Radial granulator located beneath the table.

While the small pieces produced by the rotor knife­each about 4 in. long and 0.5 in. wide­are propelled downward and into the hopper of the Radial granulator, the chamber continues moving to the upper table level.

Upon reaching the home position, the chamber begins another cycle to plane away more of the scrap part. The cycling continues until the scrap is consumed or a cycle timer elapses, providing an automatic stop to allow reloading of scrap.

The shuttle system streamlines an operation that is typically labor intensive. Size-reducing large parts usually means either cutting them with a saw before granulation or buying costly equipment, such as a massive heavy-duty granulator or combination of shredder and standard granulator. The S-20 model is said to cost no more than one-fourth that of conventional equipment.

Processors who meter pre-blended or single-component materials directly into processing machines can now control consumption and monitor throughput with a dispensing unit small enough for mounting at the extruder throat. The WST 110 Weigh Scale Totalizer also allows processors to use the Maguire Extrusion Control Network (Jun '99 PA, p 28), which is based on software embedded in Maguire Weigh Scale Blenders.

Other applications include core-layer extrusions in coextrusion and multiple processing lines fed from bulk storage.

The installed weight of the WST 110 is 160 lb, nearly half that of the WST 420 model. Batch size is 1000 gm and maximum throughput is 800 lb/hr.

Although Weigh Scale Totalizers differ from the company's Weigh Scale Blenders in having only a single hopper compartment and no mixing chamber, they operate in the same way. The Totalizer dispenses batch weights, self-compensates for material variations and tracks the cumulative weight totals of successive batches within a fraction of a pound, according to the target set-points fed into the unit's controller via the keypad or by the Extrusion Control Network. Circle 299

Key Contact B. Patrick Smith, VP Sales ­ Tel: 888-459-2412; Fax: 610-459-2700;
E-mail: [email protected];
Web Site: www.maguire.com 

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