Plug & Produce concept for silicone
14.12.2020 | Petra Rehmet

Admittedly, many aspects of reactive silicone processing are different from the familiar thermoplastic area. Many experienced injection molders are hesitant to jump to the new technology.  However, silicones—whether liquid (LSR) or solid (HTV)—are opening up new application areas all the time thanks to their physical properties. They offer great opportunities for growth. And with a system partner who is up to the task, such as KraussMaffei, the Plug & Produce concept can be applied to this material as well. 

For example, an all-electric PX 50-180 with a clamping force of 500 kN can produce four nasal cannulae in one shot. This is at a shot weight of 6.7 g in a cycle time of 24 s. For this purpose, initially, two barrels supply the fully mixed component A (consisting of base polymer, platinum catalyst, and additives) and the component B (consisting of base polymer, curing agent and inhibitor) and joined together in the mixing unit. These and the downline plasticizing unit must be cooled (approximately 20 °C) to prevent a premature reaction. In exchange, the temperature in the mold can then reach approximately 180 °C and the curing begins. 

In addition, the APC plus (Adaptive Process Control) machine function measures the viscosity of the melt and controls the filling quantity individually in the same shot. This is particularly important for batch fluctuations. However, APC plus also offers a clear advantage during a restart after a machine standstill by minimizing the number of cycles until the required shot weight consistency is reached again. Even the first shot can be run in fully automated fashion. This, in turn, saves time and money.

Producers who meet these requirements benefit from a product that resists aging and chemicals, is highly flexible, flame-resistant and free of plasticizers, in addition to being resistant to aging and bacteria. In particular, the medical and automotive industry are becoming increasingly interested in this. Another reason is that the manufacturing can be made just as compact and cost-optimized as for thermoplastics. For the nasal cannula, the entire automation is integrated into the safety cell, where an SPX 10 servo-electric sprue picker with enhanced functions removes the parts, separates them and deposits them. The compact system solution needs a footprint of less than 7 m² and has CE certification. This saves additional installation area, which means a cost advantage, specifically for cleanroom applications.  

With a complete package from KraussMaffei, silicone processing is no longer the exclusive territory of specialists. New entrants to the market also have the opportunity to take part in an exciting growth market.