All-electric machine for liquid silicone processing

Electric machines, such as KraussMaffei's EX series, have an excellent track record for production tasks demanding high precision, repeatability, and cleanliness. Variant models are available for processing a wide range of materials. An example is the EX machine in operation with Bernhard Kneifel Werkzeugbau GmbH in Bad Aibling, Germany, since spring 2010. It is being used to inject liquid silicone seals onto polyamide substrates.

The company builds moulds and tooling, and also runs a contract moulding operation, supplying components, e. g. for the white goods sector. By moving silicone seal application in-house, Kneifel has reduced its logistics effort and increased the yield of good parts it produces. To achieve its goals of high precision and low wear on the machine, Kneifel chose KraussMaffei's EX series as its technology platform.

Hallmarks of EX machines are their speed and high precision. The three-platen electric clamp unit features a Z-toggle system. The number of moving parts has been deliberately reduced. The plasticising and injection units are direct drive systems with high-torque motors. The force of two coupled electric motors is transmitted directly to the screw. Like the Z-toggle, the direct drives have been engineered to cut the number of moving parts for higher precision, more reliability, and lower wear.

Since spring 2010, Kneifel has been operating a KraussMaffei EX 80-180 SilcoSet. The machine is tasked with injecting silicone seals onto substrates made of the polyamide Grivory HT1V with 40 % glass fibre content. The substrates are produced on hydraulic machines, also from KraussMaffei, immediately prior to this operation. The outcome of the production process is a milk foaming nozzle for a coffee machine. Previously, Kneifel had outsourced the application of the seal.

By bringing this process step in-house, the company is able to save processing costs. It has eliminated the logistics effort and transport costs, and also the necessity for cleaning and reheating the substrates before applying the seal. Moreover, Kneifel now achieves a close to zero reject rate. The production cell now in operation at the company is a custom solution developed as a joint project by Kneifel and KraussMaffei. Before going into production, the system underwent a comprehensive series of tests in KraussMaffei's TechCenter in Munich.