Variable pressure scuffing of a flake graphite cast iron diesel cylinder liner

Abstract

A novel scuffing methodology was developed utilising variable specimen geometry to replicate numerically modelled top compression ring contact pressures (4–62 MPa) from a 12.8-litre heavy duty diesel engine as a function of stroke position. Scuffing of grade 250 cast iron was induced by reciprocating sliding (TE77) against a drip lubricated (PAO4) 52100 rectangular contact operating at 15 Hz and 311 N normal load by incrementing the temperature at 4°C per minute until a sharp rise in friction coefficient was observed. Scuffing initiation temperature was insensitive to dynamic contact pressure. Formation of an oxide ‘glaze’ layer resulted in friction coefficients as low as 0.03 prior to severe scuffing.