Nuremberg, Germany — As an elastomer sector with relatively high growth, LSR understandably had a significant presence with processing, machinery and materials producers among the 297 exhibitors at the July DKT Deutsche Kautschuk Tagung (German Rubber Conference) in Nuremberg.
Lossburg, Germany-based injection molding machinery producer Arburg GmbH + Co KG ran a live demonstration involving two-component molding of a 30 percent glass-fiber-reinforced polybutylene terephthalate primary and a Shore 70A hardness LSR secondary component. The component was for an automotive air conditioning vent.
Eight such parts were molded witha 40-second cycle time on an 800-metric- ton clamping force Allrounder 470A-1000 machine fitted with an 8+8-cavity rotating index plate mold. A size 70 injection unit premolded the 0.38-gram GF30-PBT primary component prior to index plate rotation to allow a secondary external piston type injection unit part mounted on the mold to overmold the LSR secondary component.
Arburg LSR technical specialist Thomas Siegel said cartridge dosing of premixed LSR was used "as this permits even the smallest shot weights to be precisely achieved."
Neustadt-Fernthal, Germany-based Dr. Boy GmbH & Co. KG used its 10-tonne clamping force XS injection molding machines equipped with a new high-precision, 8-mm-diameter screw and piston action LSR plasticizing unit to produce small 0.06 cm3 sealing rings in a mold from Nassau, Germany-based Emde Industrie-Technik GmbH, which equipped the mold with a backflow valve and microvalve gate nozzle.
Emde fitted the mold cavities with transparent windows, which enabled cross-linking of the LSR to be initiated and completed in the mold at low temperature by UV light radiation.
Boy application technology manager Michael Kleinebrahm said the fast in-mold curing with UV not only facilitates applications with long flow channels and thin-wall moldings, but also opens opportunities to use temperature-sensitive additives in LSR formulations.