Machinery, material and tooling suppliers that specialize in liquid silicone rubber were among the key players at last week’s Fakuma trade show:
KIMW Kunststoff Institut Lüdenscheid introduced a KuGlas (KunststoffGlas) project to injection overmold glass panes with thermoplastics a number of years ago. After working with compact and foamed thermoplastics, as well as back molding of high-gloss "piano black" thermoplastics, the latest version of the project, KuGlas4, now includes LSR backmolding onto glass.
This project was motivated by work in KuGlas3, showing that molding larger test pieces, beyond the size of a business card, was not feasible in thermoplastics and thermosetting plastics, while LSR results were more promising over a surface of 120 mm by 160 mm.
The KuGlas4 work will include investigations into LSR bonded onto both rigid plastics and glass to form sandwich structures that should result in 3D components, as opposed to the flat glass panes that KuGlas projects previously used. KIMW also is thinking about integrated capacitive sensors via flexible circuitry films.
The IKV plastics processing institute in Aachen, Germany, was showing injection moulded LSR optical lens that have been laser-microstructured by IKV's neighbor, Fraunhofer ILT institute for laser technology.
The exhibit was located in the Kunststoffland-NRW e.V. stand with the Fraunhofer IPT for production technology.
KraussMaffei Technologies GmbH from Munich, also displayed a lens (Fresnel type), which it moulds on a PX 50-180 SilcoSet injection moulding machine designed for LSR. The machine allows for the material's extremely low viscosity with special screw seals on the machine shaft and a spring-loaded return-flow lock on the screw. The company says the fine in-molded surface structure of the lens is not visible to the naked eye.
A KraussMaffei APC Plus control system monitors LSR viscosity, compensating for possible preliminary cross-linking, then correcting filling volume accordingly, during injection. An integrated industrial robot removes the parts from the mold, and these are then submitted to camera-based visual quality control on lens magnification to ensure freedom from flash.
LSR material supplier Momentive Performance Polymers displayed a peristaltic pump tube together with the mold for it from Rico Elastomere Projecting GmbH in Thalheim bei Wels.
Momentive says the Shore A 50 hardness Silopren LSR 4650 involved meets biocompatibility requirements such as USP Class VI and ISO 10993. This material is used in medical applications such as respiratory masks, needle-free access valves, seals and various assembled parts.
Rico also supplied the mould used by Arburg GmbH & Co KG to mould two-component watch straps in Momentive's Silopren 2670 (hardness 70, Shore A) and Silopren 2620 (hardness 20, Shore A) grades of LSR. The production line inserts watch cases into the LSR straps.
A SmartPower 120/525H/130L moulding machine exhibited by Wittmann Battenfeld GmbH of Kottingbrunn, Austria, was shown moulding a two-component part combining a thermoplastic and LSR in a 4+4-cavity mould supplied by Silital (Oldrati group) and produced by Linea Stampi srl. A Wittmann W831 robot equipped with the new R9 control system removd the parts and placed them on a conveyor belt.
With its headquarters in Eberstalzell and its customer and technology center in Schörfling/Attersee in Austria, Nexus Automation GmbH produces Servomix servo-drive LSR mixing and dosing units. The Splitnex technology used involves maintenance-free pumps and ensures air-free dosing.
Overall material loss amounts to less than 0.7%, and the Servomix E200 Advanced unit can dose from less than 0.1g amounts up to 20 l/min. Nexus demonstrated its competence in development of turnkey LSR moulding solutions with a Fanuc Roboshot injection moulding machine that it has adapted for LSR, which was displayed on the Fanuc Deutschland GmbH booth.
Established 47 years ago in Reutlingen, Germany, as a moulder of primarily LSR parts, RET Reiff Elastomertechnik GmbH has made a speciality of moulding LSR to metal. The company is proud of a component for a Bosch MRR Middle Range Radar unit that warns drivers when vehicles get too close to each other.
Aside from injection moulding, the process also includes laser pretreatment for increased bond strength to LSR, camera-based quality control and tempering of the finished parts. All processes take place automatically.
Austrian LSR mould maker, moulder and mixing and dosing equipment producer Elmet GmbH in Oftering came to Fakuma with a new Top 5000 mixing and dosing system, which has a new, more modern aesthetic front design and introduces for the first time use of labels with bar coding and letters "A" and "B" to make it unlikely for machine operators to connect the A & B component material drums the wrong way round.
Elmet's new TOP 5000 equipment was in action on the booth of Schwertberg, Austria-based injection moulding machinery producer Engel Austria GmbH, where it formed a production cell with an Engel tie-barless Victory 860/160 moulding machine.
The display unit moulded 50-mm diameter complex LSR beverage bottle venting valves in a 16-cavity mould with a cold runner, demoulding unit and an Engel Viper 40 linear part-removal robot. Engel's iQ weight control ensures reliable mould cavity filling by compensating for LSR material fluctuations.
Engel pointed out that a patented force divider enables the moving mould mounting platen to follow the mould exactly during clamping force buildup so that the clamping force is evenly distributed across the platen face. This means that outer and inner cavities are kept closed with the same force so that compression results in consistently high product quality with almost flash-free parts in a fully automatic processing.
The DOPAG mixing and dosing business of Hilger & Kern GmbH in Mannheim, Germany, presented a new Silcomix PE200/20 dosing pump for LSR at Fakuma. The company has 25 years of experience in this area, selling more than 800 Silcomix lines worldwide.
The new pump was in operation at the fair, equipped with a compact design, easy-handling mixing unit. The equipment could continuously and precisely handle all LSR materials, from extremely low to high viscosity ones. An integrated "snuff back" function closes off the valve against the direction of flow so that material dosing takes place smoothly.
A so-called SWIPSYNC pressure regulated dosing system ensures precise conformity of the required relations of mixed components, in which servo drive enables synchronous switching over of the piston pump so that the mixed ratio remains constant during the injection molding process, irrespective of small or large amounts of material. SWIPSYNC stands for Switching Point Synchronization