The break-in stage of cylinder-ring wear: A correlation between fired engines and a laboratory simulator

Abstract

The wear of the piston ring-cylinder wall contact area in fired engines has not been satisfactorily simulated in bench testers so far. This paper reports the development of a successful test device in which the same progression of surface change occurs as in fired engines. These changes were observed by microscopy, by hardness indentations and by the use of the stylus roughness tracer. The test device uses ring and cylinder segments and it oscillates at 350 cycles mm-' over a stroke of 19 mm. It is apparently not necessary to duplicate the temperature, atmosphere, fluid film thickness and other obvious conditions in an engine to achieve simulation. At least, the materials in the engine were not affected by the conditions in the engine that were not duplicated in the laboratory tester. The purpose in developing the tester was to study the role of the honed roughness pattern found on most cylinder walls. Several engine manufacturers attempt to achieve "plateau honing". No manufacturer polishes new cylinder walls. The reason for the honed roughness is to allow a high wear rate, without catastrophic scuffing, in locations of high stress between poorly conforming parts.

Scuffing mechanisms of EN-GJS 400-15 spheroidal graphite cast iron against a 52100 bearing steel in a PAO lubricated reciprocating contact

“…Wear that occurs during starvation, characterised by macroscopically observable directional modification of the surface morphology may be classified as scuffing, according to the ASTM terminology standard G40 [7]. In many cases scuffing wear is sufficiently severe to modify the surface geometry such that oil consumption and blow-by increase to an unacceptable level resulting in piston seizure [8].…”

Time Dependent Wear and Its Mechanisms in Engine Cylinders

“…The low oil viscosity is caused by the increase in the oil temperature, as it gets in contact with the hot wall surfaces. These surfaces are exposed to the products of combustion at their highest temperature, before they are covered by the piston when it reaches TDC" 1 . The lubrication around the dead centers, and in particular TDC, is believed to be of the severe boundary lubrication regime' 191 .…”

In situ stylus profilometer for a high frequency reciprocating tribometer

“…Induced changes in wear regimes can sometimes be predicted however changes arising from the contact evolution are often unexpected and consequently much more interesting. For example the quasi stability of a cyclic wear mechanism such as the removal and reforming of an oxide film during sliding wear lends itself to using a high resolution in situ wear detection technique [4] [5].…”