Appliance Design - August 2008 - (Page 25)

A handle for a Bosch refrigerator that has been in production since 2004. It is made with PME Fluidtec technology using a 30 percent glass filled PA 6. The chain saw handle is made from PA 6 GF 30 at a cycle time of 45 sec., using PME Fluidtec equipment. water finishes coring out the part. The gas bubble is still in front of the water, just compressed, and when the water is released the gas bubble wants to expand. This helps to force the water out of the cavity and the gas will follow it out of mold. Sequencing the gas and water can reduce defects such as fingering voids and still reap some cycle and cooling time benefits, Brookshaw says. This is an example of how the technology is evolving. Additional improvements to WAIM’S technology are already continuing. Companies such as PME Fluidtec have taken the technology even further with the use of multi-cavity tooling that can core several parts simultaneously. Also, in its early use, water assist had a reputation for leaks and unreliability. Better seals and injectors have been developed that has eliminated those problems, Herzog says. Resin manufacturers are working on process and material improvements that will enable its use on a growing range of applications. Testing has also begun to answer some questions about the technology. Previously, using water as a core out medium was a cause of concern over its effects on the resins’ molecular weight. Studies have shown that there are no adverse affects from water contacting the melt, Fleck says. For instance, polyesters can be sensitive to moisture in the melt, and some had questioned whether the water would degrade the polymer when the water and resin came in contact. However, Fleck says that because the melt freezes so quickly, the water does not have a chance to create any kind of hydrolytic degradation (polymer chains do not break down). To test this, he used an intrinsic viscosity (IV) test, which gives an IV value. Typically, virgin PET pellets have an IV value of around 0.52. The gas-assist molded part received a 0.47 IV, which Fleck says is a typical drop in IV value. Looking at the IV values for water-assist, and gas-assist and water-assist molding, the IV values were 0.47 and 0.48, respectively, which Fleck says is within acceptable limits. While water-assist injection molding is in its relative infancy in the U.S., in Europe the molding method has been used in the auto industry for several years. Growth in the U.S. is anticipated as potential users learn more about the technology, new resins are developed, and equipment capacity and other advancements are made. Some of which are already in the pipeline and are scheduled for release by the end of the year.< The production of the kettle handle was made with water injector technology from PME Fluidtec. It has no flash on the handle, no sinkmarks, and an even appearance. For more information, email: BASF: randy.fleck@basf.com DuPont: carole.a.davies@usa.dupont.com PME Fluidtec: B.Herzog@pme-fluidtec.de Cinpres: Brian.Brookshaw@cinpres.com The polypropylene handle of this transport cart made with PME Fluidtec equipment. www.applianceDESIGN.com applianceDESIGN August 2008 25 http://www.appliancedesign.com

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Appliance Design - August 2008 Contents Editorial Shipments/Forecasts News Watch Plastics Switches Noise & Vibration Control Joining New Products Design Marts Association Report: CEA Advertiser’s Index

Appliance Design - August 2008

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