Reducing Waste in Liquid Silicone Rubber Process Chains by New Injection Mould Process Chain

The number of components made of liquid silicon rubber (LSR) is following a global increasing trend. Due to the low viscosity, the different LSR types are suitable for injection moulding, as they can reproduce even the most complex structures. However, the low viscosity of LSR results in challenges regarding the manufacturing of the injection moulds. LSR injection mould manufacturers operate with highest effort to produce perfectly fitting mould inserts. In case of a perfect sealing, a venting of the cavities is limited, leading to defects in the moulded parts and consequently to an increase of production waste. This paper presents a far more effective process chain solving these contradictory requirements, describing new types of LSR moulding tools and an associated process chain for a resource efficient production. Experimental studies revealed the possibility of an electrical discharge dressing to generate a form fit between the mould inserts with a uniform material removal, leading to flash-free injection moulding at lowest closing forces. Thereby, the specific surface structure created by EDM presents a novel approach for venting the cavities. A resource-oriented customization of the injection moulding process can additionally reduce the energy consumption, leading to a more sustainable production.