INNOVATION | ELECTRICAL AND ELECTRONIC
From PA6 to 66
German company Wieland Electric has Domo Chemicals’ Domamid 6LVGT85 for its GST18i3 and GST18i5 installation connectors, which make up part of the “gesis” pluggable electrical installation system for buildings. Domamid 6LVGT85 is a low-viscosity PA6, certified V2 at 0.75mm with a UL Yellow card, matching the PA66 previously used for the housing shells, and top and bottom parts of the product.
Domo says the property profile with good flow and demoulding characteristics, as well as good particles crystallization, enables an optimised production process. “After a short sampling phase we selected Domamid 6LVGT85, a solution that met all our mechanical
Right: Wieland connectors make use of Domamid 6LVGT85 low viscosity PA6
and flammability specifications,” says Matthias Gewecke, Strategic Buyer at Wieland Electric. Domamid 6LVGT85 has a glow wire resistance of 850°C on both test specimens and moulded parts, which were the specific values requested on the material characterisation. “Since acquiring the Technyl brand
[from Solvay] in February 2020, Domo has offered both PA6 and PA66 materials,” says Andrea Rizzo, Sales Manager at Domo Engineered Materials. “Our philosophy is to provide customers with the best
brings together materials, machines, moulds, and technical service and engineering. Our partners have their own sales forces, which adds to our ability to access and assist the global market.” Bang up to date is a hybrid encapsulation system involving additive manufacturing and potting which has been the subject of a joint development involving a Fraunhofer institute and Arburg, with its Freeformer 3D printing system. As the Fraunhofer Institute for Manufacturing and Automation IPA points out, 3D printing not only makes it possible to produce very complex shapes that would otherwise be virtually impossi- ble to generate using conventional processes, but also enables small batch numbers to be produced on a cost-effective basis. But the integration of electronic components and the production of customised sensors has presented a challenge. Standardised inductive proximity sensors in cylindrical metal casings are used in great numbers in automation technology for non-contact detec- tion of metal objects. But the shape of the casings has prevented them from integration into specific environments such as robotic arm gripper fingers. A research team from the Centre for Additive
Production at Fraunhofer IPA asked if the sensor casing could be printed in plastic so that it could be manufactured in any shape. The answer ‘yes’ came back with the help of Arburg and the sensor and automation specialist Balluff.
50 INJECTION WORLD | October 2021
solutions for their applications and support them in gaining a competitive advantage in their field. In this case the PA66 substitution has provided multiple benefits as good flow and fast crystallisation have also resulted in better processability and cycle time reduction, not an easy achievement for a flame retardant solution with a glow wire resistance of 850°C down to 0.8mm.”
A plastic with high dielectric strength and
flame-retardant properties was required for the sensor casing. The experts opted for a PBT often used to injection mould electronic casings, but which had not yet been used for 3D printing. However, it could be used on the Arburg Free- former, which works with regular granules. The Freeformer was used to create components with cavities layer by layer, into which electronic components could be inserted during the printing process – the printer automatically stopped when coil, circuit board and plug needed to be integrat- ed, very precisely. In a separate process, a dispens- er was then used to produce the silver conductor tracks inside the casing. Finally, the cavities were then potted in polyurethane. The team produced more than 30 demonstra- tion models of customised sensors for testing to ensure they could withstand temperature changes and vibrations, that they were waterproof, and could pass an electrical insulation test. By optimis- ing the design and manufacturing process, the tests were ultimately completed successfully. The “Electronic Function Integration in Addi- tively Manufactured Components” research project ran for eighteen months. Stefan Pfeffer, who led the project at Fraunhofer IPA, is currently working with Arburg on research into how conductive plastics can also be used in the future to tap into additional application areas.
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IMAGE: WIELAND ELECTRIC
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