Originally Published EMDM September 2002
INDUSTRY NEWS
Energy-Efficient Hot-Air Oven Benefits Medical Extrusions |
| The three treatment chambers of the hot-air oven each have an integrated air-circulation system. Only 20% fresh air is introduced during the vulcanization process, thus lowering energy costs and increasing curing efficiency. |
A company that manufactures extrusion systems has developed a hot-air oven for materials processing that uses less energy than traditional equipment. By recirculating a large percentage of the heated air needed to vulcanize solid silicone rubber, the oven achieves a reduction in energy costs and an increase in efficiency. One of the extrusion systems, which are designed and manufactured by Berstorff GmbH (Hannover, Germany), was recently purchased by a device company in the Middle East to fabricate IV tubing.
The silicone rubber production line includes three hot-air-oven treatment chambers, each of which has an integrated air-circulation system. Only 20% of the process air is evacuated to remove impurities, notes Jörg Baar of Berstorff's technical rubber products division. "Because we only need to reheat 20% of the air during the vulcanization process, the oven maintains higher temperatures and produces faster cure rates, yet uses less energy than other systems." The process is especially beneficial for tubing and profiles with small cross sections that require a high energy-transfer rate, he adds.
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| Prior to vulcanization, the silicone rubber extrudate passes through a shock oven that is composed of two independent roller-mounted modules. The cavity is narrower than in previous models, bringing the material closer to the heating element and accelerating materials processing. |
Prior to vulcanization, the silicone rubber passes through a shock oven, which Berstorff also has modified to improve performance. Comprising two modules that can be set independently to a given position, angle, or height, the shock oven heats the material to 600°–700°C to prepare it for the vulcanization process. "The oven is narrower than previous units," says Bauer, "which puts the material closer to the heat source and speeds the process."
To optimize throughput, the extrusion system is fitted with a cold-feed extruder. The barrel's 60-mm screw diameter and 10 L/D ratio results in a low screw speed and minimal frictional heat, according to press officer Petra Rehmet.
Part of the Mannesmann Plastics Machinery Group, Berstorff has subsidiaries in the United Kingdom and the United States, sales offices in China and Singapore, and agents in more than 50 countries. The company has set up technical centres in Europe and the United States to assist clients in developing solutions and processes for rubber and plastics extrusion.
For additional information, contact Berstorff GmbH, An der Breiten Wiese 3-5, D-30625 Hannover, Germany; phone: +49 511 57020; fax: +49 511 561916; e-mail: info@berstorff.de; Internet: www.berstorff.de.
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