Ferritic-pearlitic ductile iron has variation in hardness while the ferritic ductile iron has homogenous hardness. Ferritic-Pearlitic ductile iron has a wide range of hardness that varies between 170-230 HB. Due to variation in hardness, it is difficult to machine ferritic-pearlitic ductile iron as compared to ferritic ductile iron. To overcome this issue, it is desirable to get ferritic microstructure without compromising the mechanical properties of ductile iron. Silicon is a ferritic stabilizer and it strengthens the ferrite phase through solution hardening. Current work is done to see the effect of silicon content on the mechanical properties of ductile iron. The silicon content is increased from 2.1% to 3.6% in different experiments to examine, and then evaluated its effect on ductile iron. It is observed that the increase in silicon content increases the ferrite phase and decreases pearlite phase, resulting in reduced tensile strength and an increase in elongation. However, further increase in the silicon content resulted in increased tensile strength as well as in percentage elongation. Effect of silicon on percentage elongation, hardness, and impact strength are observed in these experiments. Moreover, the effect of silicon on microstructure in all experiments is also studied which has a direct impact on mechanical properties of ductile iron.

Purpose This paper aims to present a technique that has been developed to study the wear in the camshaft and tappet. The engine manufacturers use the most suitable materials, lubrication additives and surface coatings to minimize friction in all the components of the engine. Reduced friction results in less wear of critical engine components. The researchers are constantly trying to find an improved lubrication formula which reduces the wear and friction coefficient at a considerably low price. In this regard, the cam follower interface is of much importance because most of the wear occurs in this interface. Design/methodology/approach The tappets and the cam lobes are analyzed to determine wear. A two-dimensional optical surface profilometer is used to measure the tappet wear, and a high-resolution linear variable differential transformer is used for the measurement of cam lobes. Tests are conducted on Mercedes Benz engine OM 646 under constant camshaft speed, constant inlet lubricant temperature and constant lubricant pressure to study the oil rheology on cam tappet wear. Findings The results show that the wear occurs on the cam tappet interface, which is almost a linear phenomenon, and it increases with use. Originality/value Customized jigs were made to measure wear of camshaft and tappet.