Five partners from the world of plastics have embarked on an ambitious project: two moulded parts made of liquid silicone (LSR), which could not have been more different in terms of their application and geometric dimensions, were to be produced in a single mould. On the one hand, a coffee lid with a shot weight of 28 g, a diameter of 100 mm, and a maximum wall thickness of 7 mm was to be produced. On the other hand, a magnifying glass with a shot weight of only 6 g and a diameter of 35 mm with a lens with 6x magnification was on the agenda.
Supported by the expert advice of Dr. Ralf-Urs Giesen and his colleagues from the University of Kassel and thanks to the provision of system technology by KraussMaffei and NEXUS, SKZ and toolcraft AG have been able to press ahead with their developments over the past three years in the production cells set up on site. The significant differences in the shot weight of the two articles quickly led to a solution approach with a cold runner mould with a valve gate.
Innovation partner GÜNTHER Heisskanaltechnik GmbH provided its valve gate nozzle with electric linear actuator for this purpose and, due to the space available on the machine’s clamping unit, supplemented it with drives offset by 90 degrees.
Meusburger Georg GmbH & Co KG contributed to the consortium with its expertise in selecting the right material for the tool steels used. “The silicone market is a stable and growing market. For us at Meusburger it was important to expand our expertise here even more in order to be able to advise customers in the best possible way,” emphasised Sebastian König, regional sales manager at Meusburger. For the planned injection mould, corrosion-resistant steels were proposed and ultimately used for the basic structure and the mould inserts.
Bestenlehrer GmbH, a tool and mould making company, is a recognized expert in the field of polishing complex cavities. The second-generation family business specialises in the distortion-free and contour-accurate polishing of injection moulding, die casting, and forming tools.
