Elmet, Momentive and Sumitomo display joint LSR project at Fakuma 2024

Oftering, Austria, October 2024 – At Fakuma 2024, the dosing and mold specialist ELMET, the LSR manufacturer Momentive and the injection molding machine manufacturer Sumitomo (SHI) Demag are presenting a joint project in which the participants have contributed their special expertise in the development, production and processing of liquid silicone rubber (LSR). The result of this collaboration is a helper in the kitchen – the Drip Guard spoon holder, which prevents drips from landing on the work surface during cooking. This demo object will be produced live at the Momentive stand (A4-4307) and distributed to visitors as a useful give-away, depending on availability.
The molded part with a shot weight of around 55 g is made from the two-component liquid silicone rubber Silopren LSR 2670 from Momentive Performance Materials. The material is characterized by low viscosity, high reactivity and good mechanical strength. Due to these material properties, this raw material has established itself in many applications that include mechanically highly resilient parts in the automotive, electrical engineering and consumer goods market segments. Thanks to the adapted reactivity, it is possible to reduce the curing temperature by around 20°C and still achieve consistent cross-linking.
To determine and optimize the exact production parameters in advance, Momentive simulated the injection molding process using Sigmasoft Virtual Molding software from Sigma Engineering. This involved carrying out filling studies and determining the required curing times at adjusted mold temperatures. In addition, the newly available specific material data of Momentive’s liquid silicone rubbers also enables the precise prediction of the expected shrinkage behaviour of the molded parts.

Momentive used Sigmasoft Virtual Moulding software to precisely determine the filling behavior of the Drip Guard during LSR injection molding. © Momentive
ELMET was responsible for the concept, design and construction of the Drip Guard mold. Injection takes place via a SMARTshot P valve gate cold runner system. A pneumatic drive ensures precise movement of the nozzle needle during injection of the liquid silicone rubber into the cavity. The nozzle of the SMARTshot cold runner system can be calibrated to precisely balance the filling process. Other features include a particularly long needle guide and 100% protection against twisting of the needle, the tip of which is part of the molding cavity contour. This concept completely eliminates production waste such as sprues.
Also from Elmet is the TOP 7000 Pro dosing system, which sets a benchmark on the market with its precise adherence to the mixing ratio between A and B components and additives, as well as its exceptional cost-effectiveness. Thanks to the innovative pump unit, the amount of LSR located in the system is extremely low. This significantly reduces the cleaning volume when changing materials. Thanks to the optimized follower plate geometry, less than 0.4 % residual quantity remains in the drum, which has a particularly cost-saving effect. The drums are changed fully automatically (from the edge of the drum), which increases ease of use and reduces the amount of training required.
The Drip Guard tool is mounted on an all-electric IntElect 130 injection molding machine from Sumitomo (SHI) Demag, which is up to 80% more efficient than hydraulic machines and characterized by its small footprint. Highly dynamic direct drives ensure maximum precision, and large bar spacing increases flexibility. Including an LSR machine package, SHI provides a complete solution for liquid silicone processing with LSR injection unit, robot, vacuum, heating, cooling and interfaces to peripherals. The data from the TOP 7000 Pro dosing system is linked directly to the processing data of the IntElect via OPC-UA, supporting a fully traceable and stable production process.