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Researchers in Germany have developed production technologies that combine a coating for components and the precision boring of cylinders to reduce engine friction and wear - with the aim to eliminate the need to run-in new cars.
Although not as necessary as in the past, many experts advise that the engine in a new car is run as smoothly as possible within the first few thousands miles of use in order to allow the engine to bed-in. During this running-in process the components in mechanical contact with one another within the engine change as a result of friction - the surfaces themselves become 'smoother' and the granularity of the microstructure becomes finer at a material depth of roughly 500 to 1000 nanometers (nm), creating a nanocrystalline layer.
However, a considerable amount of friction takes place to form this nano-scale layer on components and a large amount of energy is lost to friction during running-in. The properties of the surfaces are also dependent on the driver’s behaviour during running-in.
The Triboman research project, which involves five Fraunhofer Institutes, is focussing on improving production technologies and finishes for components exposed to particularly high levels of friction, such as engine cylinders, to reduce friction and therefore improve efficiency and reduce CO2 emissions.
Torsten Schmidt from the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz, said: “Our common approach is to move the process of forming marginalised layers to an earlier stage in production.
“For precision drilling of running surfaces on cylinders, we use defined cutting edges with a specific design. This results in very high surface quality. We also systematically use the force of the machining process to promote ‘grain refinement‘ - meaning the hardening of the materials - even during production.”
As well as friction reductions, the advancements will shorten the running-in period for new engines and reduces the risk of premature wear as a result of running in a new engine.
Researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg have already documented the first positive results of this kind of modified finishing. They used a single cylinder test engine with cylinder running surfaces of aluminium.
Analyses of the processed cylinder surfaces showed a significantly lower grain size compared to conventional methods. The surface microgeometry was comparable to the cylinder running surfaces of well-run-in cylinders.
The researchers are currently working to adapt their method to new development trends in automobile manufacturing such as the introduction of biofuels.