LABORATORY TEST RIG SIMULATION OF BORE POLISH

Bore polishing is a tribological process in which the cylinder bores o f an internal combustion engine are very mildly abraded to generate fe atureless planar surfaces with part of total loss of the honing patter n. In practice, bore polish can be controlled by lubricant formulation s and a number of industry standard engine tests have been developed a ccordingly but at very high cost. The typical cost of the present bore polish engine test, based on the Mercedes OM364A, is in excess of pou nd 30 000 a test. Considerable economic benefits could therefore be ac hieved if a simulative rig test to evaluate bore polish existed to stu dy the influence of material and lubricant chemistries prior to engine test evaluation. In this paper a pin-on-plate reciprocating tribotest rig has been developed and used to successfully discriminate between the reference lubricants (RL133 and RL134) used in the Mercedes OM364A bore polish engine test. Optical microscopy and surface profilometry were used to analyse the worn surfaces and confirm bore polish. The re sults show that bore polish was repeatedly generated under stimulated engine temperature conditions using cal bore black as oil contaminant. Further work is now required to refine the test method. (C) 1998 The Institute of Materials.