In-Mould-Metal-Spraying: Surface and partial metallisation of plastic parts

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Usually, only a fragment of the feedstock material adheres to the insert. The overspray has to be removed as it would set on movable parts of the mould and eventually damage it. Thus, the coating of the inserts takes place in an enclosed cabin. To put the coated inserts into the mould, the transfer technology seems predestined when using a basic mould with changeable cavity inserts [7]. Thus, a metallised insert can be back-moulded with plastic, while a second insert is coated.

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Diverse applications in the fields of electrical engineering, decoration

The process’ basic feasibility was confirmed in 2013. Sprayed copper tracks were back-moulded and transferred for the first time [8]. The first parts with a full or partial zinc coating were produced in 2014. Last year, the studies’ focus lay on increasing the reproducibility of the insert coating wherein various types of steel and surface treatments were examined (Figure 4). The positive impact of the mould’s reduced surface roughness on the transferability of the sprayed coating was observed [9]. A complete and partial transfer of zinc coatings on various engineering plastics such as PP, PA6 and PC could be achieved successfully as well as the transfer of complex geometrical structures (Figure 1 and 5). The influence of the melt viscosity and related injection moulding parameters on the transferability are the subject of the current investigations.

With IMMS, diverse applications arise in the fields of electronics and electrical engineering, decoration and thermal management. The production of engine control units made of plastic with integrated electromagnetic shielding is possible. Interior components in the automotive sector can provide a "cool-touch" effect with a partial metal surface. Furthermore, the cooling performance of injection-moulded heat sinks are increased by a metallised outer skin.

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Authors

Prof. Dr.-Ing. Christian Hopmann is the head of the Institute of Plastics Processing (IKV) and holds the Chair of Plastics Processing at RWTH Aachen University.

Prof. Dr.-Ing. Kirsten Bobzin is the head of the Surface Engineering Institute (IOT) and holds the Chair of Surface Technology in Mechanical Engineering at RWTH Aachen University.

M.Sc. Philipp Ochotta, is a research associate of the IKV since 2013 and heads the working group injection moulding / multi-component technology.

M.Sc. Mehmet Öte is chief engineer of the IOT since 2013 and research associate at IOT since 2010.

M. Sc. Martin Andreas Knoch is a research associate of the IOT since 2015 and heads the working group thermal spraying I since 2016.

M.Sc. Xifang Liao is a research associate of the IOT since 2013 and works in the group thermal spraying.

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Literature

[1]Grob, W., Müller, K., Habiger, E. EMC Kompendium 2003. München, publish-industry, 2003.

[2]Brosig, E. Chemisch-Kupfer sorgt für eine schützende Haut. EMV-Schutz: Kunststoffgehäuse selektiv metallisieren. Industrieanzeiger 1996, 43, pp. 44-46.

[3]Liu, A., Guo, M., Zhao, M., Hu, M. Arc Sprayed Erosion-Resistant Coating for Carbon Fiber Reinforced Polymer Matrix Composite Substrates. Surface and Coating Technology 2006, 200, pp. 3073-3077.

[4]Robitaille, F., Yandouze, M., Hind, S., Jodoin, B. Metallic Coating of Aerospace Carbon/Epoxy Composites by the Pulsed Gas Dynamic Spraying Process. Surface and Coating Technology 2009, 203, pp. 2954-2960.

[5]Bobzin, K., Hopmann, C., Kopp, N., Linke, T.F., Schulz, C., Wunderle, J. Investigation of Transferring Coatings using the In-Mould Metal Spraying Process. Proceedings of The A Coatings, Institut für Oberflächentechnik, RWTH Aachen, Aachen, 2013, pp. 1-10.

[6]Bobzin, K., Öte, M., Linke, T.F., Liao, X., Hopmann, C., Ochotta, P. Application of thermal spraying for the manufacture of metal/plastic components. Thermal Spray Bulletin. 2015, 8, pp. 23-31.

[7]Michaeli, W., Lettowsky, C. Mehrkomponentenspritzgießen. Verfahren und Möglichkeiten. Umdruck zur VDI-Fachtagung Spritzgießen, Baden-Baden, 2005.

[8]Bobzin, K., Öte, M., Linke, T.F., Schulz, C., Hopmann, C., Wunderle, J. Integration of Electrical Functionality by Transplantation of Cold Sprayed Electrical Conductive Cu Tracks via Injection Moulding. International Thermal Spray Conference 2014, Barcelona, 2014, pp. 1-6.

[9]Hopmann, C., Ochotta, P., Bobzin, K., Öte, M., Linke, T.F., Liao, X. Flächige und partielle Metallisierung von Kunststoffbauteilen mit dem In-Mould-Metal-Spraying-Verfahren. Tagungsband des 28. Internalen Kolloquiums Kunststofftechnik, Hopmann, C. Ed., Shaker Verlag, Aachen, 2016, pp. 721-732.

Acknowledgements

The depicted research referring to the In-Mould-Metal-Spraying (IMMS) has been funded by the German Research Foundation (DFG) as part of the program Cluster of Excellence "Integrative Production Technology for High-Wage Countries". We would like to extend our thanks to the DFG. ETMM

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Research & Development

In-Mould-Metal-Spraying: Surface and partial metallisation of plastic parts

Diverse applications in the fields of electrical engineering, decoration

Acknowledgements