Arburg shows its hard/soft side

Nuremberg, Germany – At DKT 2018, Arburg showed complex multi-component moulding on its electric Allrounder 470 A, equipped with an external piston type injection unit, to make automotive components from polybutylene terephthalate (PBT) and liquid silicone (LSR).

The mouldings were holding brakes, installed in air vents of car air-conditioning systems, explained Thomas Siegel, LSR expert from Arburg’s application technology consulting.

"In order to achieve a hard/soft combination, we complement a PBT pre-moulded part with an LSR component,” he explained. “We have selected a second, external piston type injection unit for this application. In conjunction with cartridge dosing for premixed LSR, this permits even the smallest shot weights to be precisely achieved.”

The 70 Shore A LSR component was then moulded onto the plastics part via a cold runner, using a second, external piston type injection unit bolted directly onto the mould. The premixed liquid silicone, which is supplied via a cartridge, was then injected vertically.

Eight holding brakes, each weighing 0.38 g were produced in a cycle time of 40 seconds. The LSR component share here is only 0.03g.