New development allows steel pistons to be used in car engines

Automotive parts manufacturer MAHLE’s new development allows steel pistons to be used in powerful passenger car engines.

The new production technology clears the way for lower fuel consumption and carbon monoxide emissions facilitating maximum design freedom for the piston gallery to ensures optimised cooling.

The technology allows the use of steel pistons in powerful passenger car diesel engines with the special laser welding process that is used allowing for a kidney-shaped cross section of the piston gallery. The kidney-shaped cross section helps guide the cooling oil flow in an optimal hydraulic path and ensures uniform heat dissipation that makes overheating impossible.

MAHLE is thus solving a problem that has existed since the invention of the cooled piston itself. Thick walls have poor heat dissipation and therefore produce high temperatures at the bowl rim.

Meanwhile, thin walls can lead to undesired high temperatures at the inner wall of the piston gallery, causing a layer of oil carbon to form. This acts as a thermal insulator and promotes undesired wear and damage to the piston and cylinder liner, owing to excessive operating temperatures.

However, such design is only feasible using the laser welding process developed by MAHLE. It is typical to use friction welding to produce pistons, but the material build up in the cooling channel hinders the controlled guidance of the cooling oil flow. The use of steel pistons in passenger car diesel engines saves fuel and thus significantly reduces carbon dioxide emissions. The reason is the lower expansion of steel relative to an aluminium piston, which has a positive effect on frictional losses. Steel pistons can also have a shorter top land and allow for a longer connecting rod with their low overall height. The smaller pivoting angle of the longer connecting rod results in smaller lateral forces and lower friction in the region of the piston skirt.

MAHLE is a leading international development partner and supplier to the automotive industry as well as a pioneer for the mobility of the future.

MAHLE Group is committed to making transportation more efficient, more environment friendly, and more comfortable by continuously optimising the combustion engine, driving forward the use of alternative fuels, and laying the foundation for the worldwide introduction of e-mobility. The group’s product portfolio addresses all the crucial issues relating to the powertrain and air conditioning technology both for drives with combustion engines and for e-mobility.

Its products are fitted in at least every second vehicle globally. Components and systems from MAHLE are also used off the road in stationary applications, for mobile machinery, rail transport, as well as marine applications.

In 2017, the group generated sales of approximately €12.8-billion and with about 78 000 employees is represented in more than 30 countries across 170 production locations.

At 16 major research and development centres in Germany, Great Britain, Luxembourg, Spain, Slovenia, the US, Brazil, Japan, China and India, around 6 100 development engineers and technicians are working on innovative solutions for the mobility of the future.

Further, MAHLE will be speaking at this year’s National Association of Automotive Component and Allied Manufacturers Show. Other speakers at the show includes DataProphet, Business Unit South Africa, Durban Automotive Cluster and many more. The show aims at being the premier automotive manufacturing growth, technology, and transformation and stakeholder engagement forum in Africa.