A study of cast chilled iron processing technology and wear evaluation of hardened gray iron for automotive application

The development of metal processing technology by cast chilled process to produce automotive parts in heterogeneous harden iron and the comparative evaluation of wear in harden gray iron is presented. The heterogeneous harden iron castings studied are the base to manufacture the bodies of engine valve lifters. The hydraulic valve lifters are precision manufactured cylinders that contact the cam to insure valve train operation and to meter lubricating oil to valve train. When valve lifters operate against the rotating came wear is produced during the automotive engine life time. A tribological study of wear in the harden faces of cast chilled valve lifters are presented. A tribometer for wear testing was used to evaluate the coefficient of friction and wear rate in time. The results indicate that the coefficient of friction and the wear rate in time of cast chilled harden iron was lower than that of standard harden iron parts obtained via thermochemical treatments. The observations and analysis of the worn surfaces, using scanning electron micrography (SEM), have allowed to explain some wear mechanisms. It was also found that the cast chilled iron processing technology is a feasible manufacturing process to produce economically automotive parts. (C) 2002 Elsevier Science B.V. All rights reserved.