BENCH WEAR TESTING OF COMMON GASOLINE-ENGINE CYLINDER BORE SURFACE PISTON-RING COMBINATIONS

In this study, two bench wear tests, the Cameron-Plint modified test ( C-P) and the Electro-Mechanical test (LS9), have been used to evaluate common internal combustion engine cylinder bore surface/piston ring p airs. Bore materials tested include cast iron, 390 aluminum, and Nikas il. Piston rings tested include chromium-plated, plasma-sprayed molybd enum, and gas-nitrided stainless steel. Both the CP and LS9 bench weal tests showed the same general trends. Gas-nitrided stainless steel ri ngs provide the lowest overall ring wear and the lowest cast iron bore wear. 390 bore wear is higher than that of cast iron or Nikasil. Chro mium-plated or gas-nitrided stainless steel rings provide the best bal ance of ring and bore wear against 390 aluminum, while molybdenum ring s against 390 produce the worst combined wear. Differences in wear rat es for 390 aluminum are related to variations in temperature and lubri cation rate between. the two testers. Bore wear measurement accuracy i s quantified and an improved measurement technique is introduced. An. initial study of surface finish effects shows that an increase in roug hness increases the friction coefficient.