Maguire: Advanced yield control provides split-second feedback

In a simple, low-cost extension of its commercially successful LineMaster (TM) extrusion yield control technology, Maguire Products, Inc. has combined the dosing precision of the Maguire (R) Weigh Scale Blender (WSB) used in standard LineMaster systems with the split-second feedback of material-consumption data provided by a loss-in-weight (LIW) hopper, the company announced today. Maguire will introduce the new technology at K 2004 (Hall 10, Stand A26).

The new LineMaster AC (TM) (for Advanced Control) system is only marginally more expensive than standard LineMaster yield control, which is priced at more than 50% less than systems available from other suppliers, according to company president Steve Maguire.
LineMaster AC yield control retrieves data on raw material consumption by the extruder at the rate of one update every 0.5 sec. ‘The high-speed responsiveness of the LineMaster AC system makes our low-cost yield control applicable even in extrusion lines where there are frequent ramp-down/ramp-up cycles, such as for film roll changeovers, or where inconsistencies in extrusion rate pose especially great problems, such as in coextrusion,’ Maguire said. ‘Until now, processors with such operations have had to settle for far more cumbersome and costly yield control systems based on LIW blenders. For example, these conventional systems require separate controllers for a LIW blender and a LIW hopper.’

LineMaster yield control centers on a gain-in-weight blender, the Maguire WSB, which provides precise control over batch formulation by sequentially dispensing ingredients, in targeted recipe proportions, from separate bins into a weigh chamber. In the LineMaster AC system, the blender batch is fed into a LIW hopper mounted at the extruder throat. The load cell in the hopper provides updates on material consumption at the rate of one every half-second to
the WSB, which is mounted either atop the hopper or on a floor stand. Loaded in the WSB controller is the LineMaster yield control software, which regulates extruder and haul-off speeds in accordance with input on raw material consumption.

Investment in WSB-Based Yield Control Is up to 50% Less than Conventional Systems

Maguire offers the LineMaster AC system as an optional alternative to its standard LineMaster yield control. The LIW hopper initially available for the advance system is the Model XC-LIW 10 unit, with 22-lb. (10- kg) capacity. ‘We expect to have three different hopper sizes, serving throughputs up to 5,000 lb [2,270 kg] per hour,’ said B. Patrick Smith, Maguire’s vice president of sales and marketing.

The XC-LIW10 hopper adds USD $3,000 to the cost of LineMaster yield control, for a total (including hardware and software) ranging from $5,000 to 8,500, depending on the level of control desired by the processor. By comparison, according to Smith, conventional yield control systems are priced in the range of $12,000 to more than $50,000.

Benefits of Yield Control: Quality Assurance, Material Savings, Reduced Downtime

‘WSB-based control can reduce cost and increase productivity in virtually any extrusion operation by automatically regulating extruder throughput, line speed, and, ultimately, the quantity of material that actually goes into a specific length of product,’ Smith said. ‘In addition, by rapidly adjusting process parameters to achieve target product tolerances, it reduces setup times and saves on startup and job-changeover scrap.’

Extrusion accounts for 60% of the 20,000 Maguire WSBs in use, Smith noted. ‘LineMaster technology is readily adaptable in every application where our blenders are now deployed, including film, sheet, coating, pipe, profile, wire and cable, and compounding.’

In both standard LineMaster and LineMaster AC systems, extrusion control is available at
three levels of cost and performance:

▪ XC-1, an extrusion control system in which the WSB controller automatically adjusts
only one parameter-extruder speed-to achieve a manually set target throughput (weight of raw
material processed per unit of time).

▪ XC-2, a basic type of yield control in which the WSB controller once again automatically adjusts only extruder speed, but does so by first calculating target throughput on the basis of two manually set parameters: target haul-off speed (length of product per unit of
time) and target yield (weight per length of extruded product).

▪ XC-3, a total system for yield control in which the WSB controller simultaneously adjusts both extruder and haul-off speeds to achieve target yield, providing complete control of the process. The interface for coordinating these process parameters is Maguire’s Gravimetric Gateway (TM), or ‘G2,’ software for integrating blenders in a computer controlled network. Different versions of G2 software are loaded in a PC and in the WSB controller (or multiple controllers, in the case of a coextrusion line). While G2 software is available as an option for networking blenders implementing XC-1 and XC-2 extrusion control, it is mandatory with XC-3 yield control.

The LineMaster AC system is available for XC-1, XC-2, and XC-3 control systems. The key difference from standard LineMaster technology is that the data on extruder raw material consumption provided to the WSB controller comes from the LIW hopper instead from the weighing system in the WSB itself. While the WSB operates from batch to batch, the LIW hopper continuously feeds material into the extruder and thus provides a steady stream of data on material consumption.

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