Honsel makes gasoline and diesel engines much more economical for the future. At the "Aachener
Colloquium" on engine and automotive technology which took place from October 5-7th in Germany, Honsel presented a new type of coating process for cylinder bores. This highly innovative coating reduces friction between piston and cylinder in aluminium engine housings, which in turn also cuts fuel consumption. It also makes the engine much lighter because coated cylinder bores weigh much less than cast-in linings of grey iron. Moreover, the ultra thin steel coating offers excellent thermo-mechanical conditions for modern engines with high power density. And Honsel's solution costs significantly less than other types of cylinder coating.
Light, non-expendable and inexpensive: with an ultra thin steel coating for cylinder bores in aluminium crankcases (fig. above) Honsel helps to reduce fuel consumption and emissions still more efficient than with conventional heavy cast-in linings of grey-iron.
In order to save weight and fuel consumption, crankcases in modern gasoline and diesel engines are often made of lightweight aluminium instead of heavy grey iron. However, to allow the pistons to run smoothly in the aluminium cylinders, linings of thick grey iron had to be cast into the crankcases, or the surface of the cylinder walls has to be coated by means of an expensive and time consuming process. Honsel has now developed a much cheaper coating process, where a very fine layer of steel is applied to the cylinder bores by means of a plasma particle jet. "This coating reduces the fuel consumption and therefore the amount of CO2 produced because it substantially diminishes the amount of friction between the piston and the wall of the cylinder bore," explained Dr. Bernhard Gand,
head of Honsel's engine-development. Unlike the grey-iron inserts, the aluminium bores thinly coated with steel are extremely light. Due to its high surface quality, Honsel's new coating not only cuts down friction, but shows no sign of wear during the lifetime of the engine, thereby keeping oil consumption low. Compared to other types of coating for aluminium cylinder bores, the Honsel solution offers considerable potential for saving costs during engine manufacture. "Our coating process fulfils all the demands made by manufacturers on cylinder bores. It is the latest example of the technologically exacting and economically beneficial lightweight solutions produced by Honsel to allow the engine of the future to use less fuel and emit less CO2. This is one of our contributions to environmental protection and sustainable mobility," said Bernhard Gand, summarising the philosophy behind engine development at Honsel. In principle, the new coating process can be used in combination with all the processes used for casting aluminium cylinder crankcases. However, Honsel has also developed a new die-casting process specially adapted to the requirements of the subsequent coating process, which takes account of the need for a very fine metallographic structure in the cylinder area and high loading capacity of the crankshaft-bearing blocks.
Before the actual coating, the inner walls of the cylinder are activated by mechanical machining in order to create the best possible conditions for adhesion of the coating. A computer-controlled machine then approaches cylinder wall and coats the surface with molten steel by means of a plasma
particle jet. After this, the layer only has to be ground down to the appropriate thickness and honed to make it extremely smooth. In this process, the coating parameters as well as the honing process can be individually adapted to the various requirements of modern engines with regard to cylinder linings.
This innovation from Honsel can be used universally for all gasoline and diesel engines regardless of size or number of cylinders. The coating is approved for all types of fuel including alternatives such as ethanol, biodiesel, natural gas or BtL (biomass to liquid). Honsel is currently working on a number of development projects for automotive manufacturers who intend to use crankcases coated by the Honsel process in their highvolume models.