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September 2, 2003

6 Min Read
In Process


An innovative extrusion line design eliminates downstream insertion of molded components, creating an inline system to make irrigation pipes with embossed PE-tape lining. Drip Research Technology Services Ltd. (San Diego, CA) and Cincinnati Extrusion GmbH (Vienna, Austria) teamed up to create the all-new continuous production pipe-extrusion line.

In conventional systems, molded drippers are inserted into the pipe just after extrusion through the rear of a crosshead at preset intervals. Mechanical insertion of these components required sophisticated secondary operation automation. In the new design, the drippers are replaced with embossed PE tape. The embossing handles pressure control in the pipes, creating a more stable irrigation system that precisely meters water amounts. To adjust the irrigation design, the embossing module can be altered in the production line.

The irrigation extrusion system includes an Alpha 45 single-screw extruder that uses a special die to extrude the PE tape, which is then embossed with a downstream embossing unit. At that point, a special feeding unit inserts the tape into the crosshead of the second extruder. The irrigation pipe, which has a 20-mm outer diameter and a thickness of .015 to .20 mm, is created by a Proton 60 single-screw extruder, and a specially designed crosshead feeds the tape into the pipe?s interior. Next, the tape is welded directly onto the pipe in the calibration unit. The pipe is cooled in a full-batch cooling aggregate laid out for high-speed extrusion. Holes to release water are punched into the pipe in the haul-off unit at predetermined locations. In the final step of the process, the pipe is wound by an automatic winder.

The system provides extrusion speeds of 100 m/min, and in addition to the ability to adjust the embossed tape to the irrigation needs, it is said to be more cost-effective than using two separate systems. For more information, contact Cincinnati Extrusion GmbH at +43 161 0060 or visit the company at www.cet-austria.com.


By applying new drying technology, a custom compounder turns around customer testing requests in one day. LNP Engineering Plastics (Exton, PA), a division of GE Plastics, recently installed five low-pressure vacuum dryers from Maguire Products (Aston, PA) in its injection molding test specimen laboratory and reportedly watched its drying time drop from four to six hours to less than one. LNP used to test five to seven specimens/shift based on 50 to 75 shots/specimen, but now it examines 10 to 12.

The lab features four injection molding machines, which create specimen plaques and dog-bone shaped parts for tensile-strength tests. The company also performs tests for customers. LNP normally responds to the receipt of a customer sample after only 40 minutes, but the company?s previous dryer technology meant it couldn?t finish the order until the following day. The new system allows faster response.

Part of the productivity is attributed to a unique canister design created especially by Maguire for the project. The custom-built sealed canisters are mounted on top of the molding machines to eliminate any exposure to ambient atmosphere. This design also allows rapid switches from material in one dryer to material in another.

The Low-Pressure Dryers (LPD) use no desiccant, instead, hot-air flows over the pellets in a vacuum atmosphere, which lowers the boiling point of the water. Heating and vacuum drying are performed simultaneously in separate stations for a continuous process. For more information visit Maguire Products at www.maguire.com.


In an attempt to serve the future needs of an ever-expanding wood-fiber market, the University of Maine?s Advanced Engineered Wood Composites Center (AEWC) is using the Crompton Davis-Standard Woodtruder for several advanced research and development projects. The university is working with multiple government agencies and private organizations to develop new wood-fiber products that pair polymers with lumber in new applications.

The Coast Guard has called on the school and the Woodtruder to produce new decking and retaining wall products to replace pressure-treated wood. Decking material has already been created for the fabrication of a new pier. Work is also being done in conjunction with the USDA to study post-die process conditions in order to see how cooling rates impact product development. Work with the USDA is also being done to create nylon/wood products for automotive applications. The Woodtruder involved in this research consists of a tandem extrusion arrangement that uses a primary 28:1 parallel twin-screw extruder, and a mounted single-screw side-injection extruder. In the first section, a primary extruder uses a heating and vacuum-venting system to remove moisture and volatiles from the wood fiber.

The side-injection extruder, which is located halfway through the primary extruder, heats and mixes the polymers. Wood-to-fiber ratios are chosen, and then polymers are injected into the primary extruder, where the mixture is homogenized. The wood fibers are encapsulated by the polymers, which are introduced in a molten state. This results in a thoroughly mixed composite product that can feature up to 60 percent wood fiber.

The design allows fibers as varied as saw dust, wood, sisal, rice husks, flax, peanut shells, and recycled car tires to be processed. The setup also eliminates the need for wood-drying equipment. The aforementioned fibers can be joined with PP, PS, HDPE, and PVC. Research is underway to join the fibers with engineering thermoplastics.

For more information about the research and development at the University of Maine?s AEWC call (207) 581-2846. To learn about the Woodtruder call (860) 599-1010 or visit www.davis-standard.com.


By limiting operator interaction with filled boxes to once or twice a shift, the installation of six box-filling conveyors at a San Antonio, TX molder has reportedly lowered annual labor costs by $72,000/yr. DynaCon conveyors were installed at GW Plastics a year and a half ago to automate packing of new molded seat-belt and signal-switch assembly components. The conveyors measure up to 21 ft and have Intralox modular flat-top belts and flights.

The manufacturing cells are designed so that boxes are loaded at the center of the conveyor. A cycle counter determines if a box is full, and then the system indexes forward to the next box. All operators are required to do is occasionally remove filled boxes from the front of the conveyor and load new empty boxes onto the back of the line.

Prior to installation of the DynaCon lines, operator interaction occurred roughly every half hour. The heightened efficiency of the new system has reduced that to once every eight hours, and GW says this has lowered labor costs by approximately $6000/month. The conveyors? flexible design also means that as customers alter product lines, the units can be reconfigured rather than abandoned.

GW recently shifted several lines for process-optimization purposes. When a box size changed, the holding cells on the belts were too large?but instead of replacing each system at a cost of roughly $1000 apiece, GW changed the spacing between the belt flights in one afternoon. By pulling out the belt rods and the flights, flat-top modules can be inserted, allowing users to move the flights to a different location on the belt.

GW has standardized all its plants to use DynaCon box-filling and incline conveyors. It cites instances where 30-ft conveyors have been split into three 10-ft conveyors as further examples of the system?s flexibility. Part of this derives from DynaCon?s partnership with Intralox (Harahan, LA) and its unique belt design. Conveyors can have belt widths of 60 inches or more, with a variety of design options, including inclines, turns, and drainage applications. For more information, contact Dynamic Conveyor at (800) 640-6850 or visit www.dynamicconveyor.com. To contact Intralox call (800) 535-8848 or visit www.intralox.com.

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