KraussMaffei’s system for LSR coffee cup lids

Silicone is flexible, antibacterial, temperature-resistant, durable and it does not contain any plasticisers. These properties make liquid silicone rubber (LSR) the ideal raw material for coffee cup lids.

To enable the production of LSR coffee cup lids, German machinery maker KraussMaffei has put together a network of partners, such as toolmaker ACH Solution and material manufacturer Wacker Chemie, which provides its Elastisol LR5040 series.

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Using the turnkey system, two different covers are created in one shot on KraussMaffei’s fully electric PX 121-180 SilcoSet. One is for thick-walled porcelain cups and one for the well-known Recup deposit system, which is now widespread in many cities and regions. The article weights are 38 and 50 g, whereby the heavier Recup lid has a decorative feature. The attached tab can be decorated with advertising or a small message by laser.

The greatest challenge when processing LSR is its low viscosity. The mould has to close extremely tightly in order to achieve a stable process; very often a vacuum is even applied. In addition, the temperature control is reversed compared to thermoplastics. The tool is heated so that the crosslinking process can even start.

On the machine side, the perfect sealing of the dosing and injection unit is also important. Since silicones are subject to comparatively large batches and the resulting process fluctuations, particular attention must be paid to the constant weight of the manufactured components.

KraussMaffei’s APC plus machine function determines the viscosity of the material during production and adjusts the filling volume from shot to shot in the cycle.

After removal and camera inspection for complete demoulding and geometrical correctness, the coffee lids are then ready for use without being tempered.

Krauss Maffei adds, “With the right partner, it is so easy and risk-free to participate in the silicone growth market.” Further growth rates are already being predicted, it emphasises.


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