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As for the polyamide (nylon) resins, i.e., nylon 6, nylon 66, nylon 46 and so on, when they are reinforced by glass fibers (GF), their static mechanical strength and heat distortion temperature increase considerably, and many faults of them are improved. However, when repeating stress is applied to a GF-reinforced nylon, the interface stress concentration between nylon and GF is easily to happen and so, depending upon working condition, the damage phenomenon similar to fatigue flaking is often observed for the GF-reinforced nylon by the reason of the insufficiency of interface strength between nylon and GF. In this study, thus, it mainly focused on the improvement of the fatigue property of GF-reinforced nylon. Actually, we compounded of nylon 66 and GF the fiber diameter of which was smaller than conventional GF, and investigated the mechanical and physical properties of the nylon 66 / GF composite we prepared.

The belt-type continuous variable transmission (b-CVT) consists of a simple structure that transmits power by using a steel push belt in combination with a pulley. One important factor that leads to the deterioration of rolling bearing life is influence of additives in the special traction oil (CVT fluid). CVT fluid is mixed various additives to increase friction coefficient with the aim of maximizing sliding performance between the metal belt and pulley surface areas. In order to restrain heat generation due to friction driving between the metal belt and the pulleys, and to minimize churning resistance of the gears in the unit, viscous resistance of CVT fluid is designated at a lower class than that of gear lubrication oil used in manual transmissions. As a result, formation of an oil film is impeded throughout the bearing interior, creating harsher operating conditions that those found in conventional transmissions.

Bearings used in electrical engine-driven accessories, such as alternators and air conditioner (A/C) compressor pulleys, generate flaking related to non-metallic inclusions of unusual microstructure (white structure flaking), which occurs at one-tenth to one-twentieth of the calculated bearing life. In this paper, we will describe our investigation of the mechanism of white structure flaking, and report on how we achieved extended service life of engine-driven accessory bearings by implementing an evaluation of white structure flaking based on the discovered mechanism. We verified that the tribochemical reaction of grease, and statistic electricity generated by friction between the drive belt and pulley were the main culprits of white structure flaking. White structure flaking was further augmented by hydrogen invading the bearing steel, which further impaired bearing life.

Lubricant contamination is a frequent hazard to bearing life in automotive transmissions. The “Sealed Clean” bearing concept uses dynamic, rubber seals to exclude significant contamination from transmission bearings. However there is often insufficient space in a roller bearing application to accommodate seals. HTF steel specifications and processing were developed for such applications. Debris within a rotating bearing will create indentations in the raceway. Contact stress is concentrated at the indentation edges and fatigue damage is accelerated. A indentation's diameter and edge radius determine the stress concentration between the ball and raceway. The HTF steel specification and tightly controlled heat treatment processing have been developed to provide long life despite the contamination hazard. Testing confirms the effectiveness of the new material.