Abstract No.:

New quality diagnostic methods for continuous improvement of the twin wire arc spray process

Johannes König* / Daimler AG, Germany
Michael Lahres / Daimler AG, Germany
Oliver Methner/ Daimler AG, Germany

Because of the lightweight construction strategy of Daimler Inc. the core component of the passenger car engine is manufactured from aluminium since over 30 years. Substituting the common cylinder liners is done nowadays through a thin twin wire arc sprayed metallic coating (LDS®  technology). The as-deposited coating is finished through an adapted multi-stage honing process towards the demanded functional surface structure. The advantages of this technology are evident. Because of the custom-made iron based coating the friction loss can be decreased significant accompanied by reduced CO2- and fuel consumption.

To apply this technology to the whole engine family, the LDS®-torch must be designed and optimized respectively. The gas flow which guides the particles towards the bore surface has tremendous influence on the coating development. A test bench was developed which measures the pure gas flow concerning shape and velocity. Especially for testing the function of prototypes this created test bench (on basis of a CFD-simulation) is suitable in the very early stage for the torch development. The results are confirmed through striation optics which deliver additional informations about the flow. With this method, it can also be established the approval of new designed or maintenanced LDS®-torches for serial production.

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