Rotary machine takes on reciprocating screw, shuttle unitsRotary machine takes on reciprocating screw, shuttle units

The SB (small bottle) series of rotary blowmolding systems from Wilmington Machinery-one of the few firms making rotary machines-is said to offer considerable savings to processors of 100- to 500-ml single-serve containers in either mono- or multilayer designs.

The manufacturer says the rotary unit, with its high output, is marketed at a price competitive with shuttle and reciprocating machinery. The high cost of rotary machines has kept them out of the market except for very high-volume projects, but Wilmington thinks this new unit might change that.

Wilmington offers substantial data to support its expectations. A monolayer, 30-cavity SB machine would most likely compete directly with reciprocating screw-type machines, notes Wilmington, but a processor would need two reciprocating machines to match the capacity of a single SB system.

Reciprocating machines have electric drives for the extruder, as does the SB system. However, the single SB system has only a single three-hp motor to drive its clamping system as compared to 80 to 120 hp for the two reciprocating units. Taking 80 hp over 8000 hours at $.08/kW produces an additional saving of about $38,000/yr.

The SB units also reduce hot flash (typically tails and blow dome) by as much a 33% compared to other extrusion blowmolding processes. As a result, processors do not need to push as much material through the barrel to achieve the same output, and less material plasticated also means energy, and material, saved.

The SB Series machines are available with 18 to 60 cavities in one- to seven-layer extrusion configurations. A 30-cavity machine running a 7-second cycle produces 260 bottles/min.

Expected applications include liquid yogurt, single-serve dairy products, hot-fill drinks, juices, and single-serve retort beverages. Wilmington Machinery, Wilmington, NC, USA; www.wilmingtonmachinery.com