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The aspects of real engineering surfaces are discussed with regard to their three-dimensional nature. A review of potential uses of surface finish measurement methods are discussed for characterization of functional surfaces. The use of an optical-based system and measurement procedures are discussed as a means of differentiating surface roughness and its texture of functional surfaces by surface engineering parameters. Using an optical-based system and a set of specific measurement procedures, two functional surfaces with different roughness were analyzed to illustrate a typical surface topography evaluation. A simple sliding test is then utilized to show that a special finish produced by a proprietary finishing process can provide improved performance, as measured by wear differences, frictional properties and operating temperature of the system.

Predicting fatigue performance in concentrated contacts under thin film (or mixed) lubrication conditions has historically involved various empirical approaches. Typically a lubrication parameter is used in an experimentally derived equation to predict the expected rolling contact performance. However, this model doesn't explain the performance improvements. Enhanced finish bearings have exhibited longer life than standard finish bearings, especially when bearings are operated with thin EHL film. In this paper, the contact surfaces of test bearings were analyzed by using a micro-macro contact model in which the macro-contact was elastic contact, and the micro-contact was elastic-plastic contact. The interior subsurface stress maps were calculated from the real contact surfaces, which included the effects of roughnesses, waviness, and profiles.

Lubricant formulations and lubricant additives have been slanted heavily toward protecting gear concentrated contacts from galling and wear. Much of the performance differentiation of these lubricants has been dependent on highly accelerated standardized laboratory testing. The area of contact fatigue has played a less important role in shaping lubricant formulations, but new test results for several commercially available gear lubricants suggest this area warrants a closer examintion. The implications of these findings for equipment applications are discussed, and suggestions are made for ways to minimize or avoid potential detrimental performance effects.

An experimental study of two warm and hot forged 0.30% carbon ferrite/pearlite microalloyed steels demonstrates that the optimal combination of strength and toughness is achieved in a warm forged, fan cooled condition. The properties of the warm forged microalloyed steel approached the combination of strength and toughness achieved in a heat treated 1037 steel, tested at an equivalent hardness level of 20 to 28 HRC. These warm forged microalloyed steels were successfully substituted for heat treated 1037/1040 steels in two automotive transmission hub applications. The benefits of implementing the warm forged microalloyed steel hubs include the elimination of the heat treatment, and the associated costs and problems.

This paper is focusing on the performance enhancement of the tapered roller bearings supporting the transfer shaft in a push belt type Continuously Variable Transmission (CVT). It also provides an objective comparison, based on test results, with the fixed/floating ball bearings alternative arrangement. The influence of different design parameters such as cup and cone race profile, roller length / diameter ratio, surface finish etc., is quantified in the analytical and experimental investigation. The bearings power loss is calculated and measured for operating conditions that are relevant in a vehicle fuel economy cycle. Additional specific aspects related to the use of tapered roller bearings, such as setting and mounting procedures, are discussed under similar considerations. The paper contains a system analysis of the transfer shaft interacting with the variator output shaft and with the differential.

Gas carburized and quenched low alloy steels typically produce surface microstructures which contain martensite, retained austenite and often NMTP's (non-martensitic transformation products). The NMTP's are caused by a reduction of surface hardenability in the carburizing process from loss of alloying elements to oxidation. Gas carburized low alloy steels such as SAE 8620 with NMTP's on the surface have been shown to have inferior bending fatigue properties when compared to more highly alloyed steels which do not form NMTP's, such as SAE 4615M. One method of minimizing the formation of oxides and eliminating NMTP formation during carburizing and quenching is to use plasma carburizing instead of conventional gas carburizing. In this study the microstructures and bending fatigue performance of plasma carburized SAE 8620 and SAE 4615M is compared to the same alloys conventionally gas carburized and quenched.