Characteristics of extrude honed SG iron internal primitives

Importance of generating and finishing engineered surfaces is increasing owing to stringent parametric requirements to achieve desired functionality. This has necessitated (1) generation of surfaces with required texture, and (2) evaluation of generated surface to ensure whether it serves the intended purpose. Several new techniques have been studied to overcome the processing constraints of traditional surface finishing methods. Mostly abrasion processes are adopted for achieving the required surface finish and texture. However rigid abrasive processes induce, thermal damage. Hence flexible abrasion such as lapping can be safely used. Yet another flexible process that can be used for finishing of internal forms is extrude honing. In this study, extrude honing of SG Cast Iron (600grade) has been successfully performed in a laboratory model of hydraulically actuated extrude honing set-up using a select grade of polymer as abrasive carrier medium. SiC grit of 36 mesh size is used as abrasive. Generated surfaces were evaluated in terms of surface roughness, bearing area fraction, out of roundness, induced residual stress and macrography. Results show a significant improvement in surface finish properties. Details are presented in this paper with relevant illustrations.