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The total amount of exhaust emissions from diesel engines all over the world must be reduced. Off-road machines consume a considerable part of the diesel fuel used in Sweden and much of the exhaust emissions originate from these machines. Consequently, it is urgent to study different methods to reduce fuel consumption and the exhaust emissions from off-road machines. The test-cycles used to calculate exhaust emissions from off-road machines are developed for heavy on-road vehicles, e.g. trucks and busses. A pilot study at JTI indicates that calculation of the amount of emission based on these test-cycles may give completely wrong figures. More relevant test-cycles have to be established.

This paper is discussing how a specific machining problem was resolved. The part is an engine cylinder liner made of PM steel. The liner had to be machined by the engine manufacturer after it was cast in place in an aluminum engine block. The liner was bored in a customized transfer machining line, with the machining parameters set for boring of gray cast iron or eutectic aluminum engine bore. The developed technology permits machining of PM carbon steel at surface speed at or above 700 m*min-1 in both wet and dry condition using CBN (cubic boron nitride) material in the insert. The liner is surface treated in the bore prior to the aluminum casting process and the liner material has an elevated content of iron sulfide (FeS) enhancing the machinability of the liners. The cost of machining is today in parity to conventional products. There are still options for further improvements.

AB Carbox in Sweden, together with Höganäs AB and a large manufacturer of cylinder liners, has been working since 1975 on the development of a new method to manufacture cylinder liners in sponge iron for combustion engines. Utilization of the P/M process has resulted in a 20-40% cost savings when comparing P/M liners to cast iron liners. A highly mechanized and modern manufacturing method, the P/M process can be adopted for the welfare of labor and the environment.