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Following a major upgrade, optical disc manufacturer Sonopress Inc. is receiving pressurized bulk delivery of compact-disc-grade polycarbonate resin directly into storage silos at its Weaverville, N.C., plant.

Resin supplier Bayer Corp., materials-handling system provider Motan Inc. and transporter Chemical Leaman Tank Lines Inc. collaborated with Sonopress in adapting aspects of established European systems for what the participants believe to be the first U.S. installation of this type.

Since April 2, ``We have taken about 10 loads of material and things are going well,'' Sonopress injection molding specialist Ron Boissonneault said in a May 21 interview.

Holding company Bertelsmann AG of Gutersloh, Germany, owns Sonopress.

Previously, Sonopress workers transported 1,500-pound resin bags on pallets from off-site storage and required 10-15 minutes to hopper-load each of 15-20 bags used in daily production. The new system saves labor, boosts material-handling efficiency and reduces the risk of resin contamination.

Resin-purity requirements for CDs ``are equal to, or greater than, what they do in the medical field,'' and thresholds for new DVDs are ``even more stringent,'' according to Ramesh Pisipati, industry manager of optical memory with Bayer's Polymers Division in Pittsburgh.

``In Europe, we have been servicing a number of large optical disc customers with bulk delivery systems for five years,'' Pisipati said. ``We learned from experience.''

Units of German parents Bayer AG in Leverkusen and Motan Holding GmbH in Konstanz cooperated with Sonopress in the European project.

In addition to Bayer, GE Plastics and Teijin Chemical Ltd. bulk-deliver CD-grade PC in trucks to certain European processors.

Initial talks on improving the Weaverville operation began in August 1995, and planning got serious early last year when the development team took a critical look at a Sonopress molding site in Gutersloh.

``We added a few [features] and took away [some],'' Boissonneault said.

In Europe, for example, ``They tilt tanks to blow the resin out of the truck,'' he said. ``We pressurize [the tank] and blow [resin] out the bottom of the truck.''

Chemical Leaman's dry bulk services division transports 40,000-pound loads in a pressurized container that is mounted on a flatbed trailer.

``Now, we can transport dry bulk resin with a new level of cleanliness,'' said Rich Ramach, operations director in Exton, Pa.

The company arranged for building of the container and truck.

Subsidiary Motan Inc. designed the material hose and air connectors, complete stainless steel valving, three silos and custom semiautomatic controls at its Plainwell, Mich., facility, according to Douglas Arndt, technical services director.

Air inlets and material outlets were brought to a central point in the container.

Oil-free blowers with high-efficiency particulate-air filters pressure-convey the PC resin from the trailer to one of the 30-foot-high, 10-foot-diameter silos. Each weighs 10,000 pounds when empty, holds as much as 50,000 pounds of resin and sits on four load cells that can calculate the weight within 20 pounds.

A Motan vacuum conveyer moves the resin in steps to surge bins, drying bins and injection molding presses.

``It all came down to material handling,'' Arndt said.

Upgrades continue.

``The control system can trace a material lot through the silo and, later this year, through processes on the production floor,'' Arndt said.

Sonopress' Boissonneault said Bayer ``invested substantially to make this system possible.''