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Today, especially medium duty engine platforms have to fulfill a wide spread of applications and thus also power ratings. With heavy duty engines being already for a long time in a peak cylinder pressure range above 20MPa, forged steel pistons have become an industry wide standard. However, for medium duty, many engines still utilize Aluminium piston technologies due to mainly economic reasons and operating conditions at lower peak cylinder pressures. The drawback of this situation is a lower performance in terms of thermal efficiency and thus fuel consumption. This becomes even more important, when CO2-based regulations might come into action. Recently, medium duty platforms are developed with variants that need forged steel pistons due to their peak cylinder pressure requirements, causing rather a high degree of fragmentation of engine components.

Total cost of ownership is requiring further improvements to piston friction reduction as well as additional gains in thermal efficiency. A piston compression height reduction in combination with carbon based piston pin coatings is enabling advancements in both demands. MAHLE implemented a new innovative metal joining technology by using laser welding to generate a cooling gallery. The MonoLite concept offers design flexibility which cannot be matched by any other welding process. Especially an optimum design and position of the cooling gallery as well as durability for very high peak cylinder pressures can be matched. This is particularly advantageous for complex combustion bowl geometries that are needed in modern diesel engines to meet fuel economy and emission requirements. The MonoLite steel piston technology offers a superior compression height reduction potential compared to typical friction welded designs.