Skoda introduces plasma-coated cylinder blocks

- Introduces new processing line for plasma coating in cylinder blocks

- Skoda Auto invested a total of 28.8 million Euros

Skoda Auto has introduced a new processing line for plasma coating in cylinder blocks. This technically innovative concept allows conventional cylinder liners to be replaced with a powder coating that measures just 150μm (0.15 mm). This will now be used when producing the new EVO three-cylinder engines from the EA211 series and will reduce internal friction. As a result, the 1.0 TSI EVO petrol engines will be even more efficient and boast lower emissions. Skoda has invested a total of around 29 million euros in preparing and converting its Mlada Boleslav-based headquarters. 

The Czech car manufacturer has added an assembly line with two special fixtures for plasma coating at its main plant. Both of these include two torches. During the production process, the cylinders are first bored on the machining line. A 1,500-watt laser then abrades the cylinder bores to ensure that the plasma layer will optimally adhere to the surface. This involves the laser beam creating ten grooves per millimetre, each measuring an average depth of 40μm. This production step takes place in a controlled atmosphere filled with nitrogen to keep the laser’s optics free from contamination and to ensure the necessary level of accuracy.

A mixture of hydrogen and argon is used to create plasma gas, requiring 4.5-litres of hydrogen per minute during the process. The plasma reaches a temperature of 15,000° Celsius and is then mixed with various types of steel that have been ground into fine powder. This powder is made up of iron, carbon, silicon and manganese as well as other necessary elements. The individual powder grains measure no more than 50μm. When sprayed onto the cylinder walls, the molten powder forms a layer measuring approximately 250μm. During final processing, this layer is honed out, so that it measures just 150μm. The wall of a conventional cylinder liner is 4mm thick.

Each cylinder is automatically measured at several stages throughout the process to assess its quality. Optical measuring instruments first record the surface abraded by the laser, before and then a second measurement is taken after the plasma has been applied. Finally, the structure of the plasma layer is tested using turbulent flow.

The engines featuring plasma coating are also used in the Skoda Octavia e-TEC mild hybrids. This technology is expected to be introduced in the Volkswagen Taigun and the Skoda Vision-IN as well.