The essence of the poor lubrication of the hard-tooth surface F97-Y7.5-NA40-M4 reducer bearing is that 'the lubricating medium does not continuously and stably act on the rolling contact surface of the bearing according to the design requirements.' The reason can be disassembled from the four core dimensions of the lubricating medium itself, lubrication system/structure, installation operation, and working environment . The specific analysis is as follows:
1. Reasons related to lubricating media (core factors)
The performance, state or Selection of the lubricating medium (usually gear oil, some bearings use grease alone) directly determines the lubrication effect, and is the most common source of failure:
Lubricating oil Selection error
Failure to select the oil according to the requirements of the reducer manual: for example, misuse of low-viscosity oil (unable to form a sufficient oil film, resulting in direct metal contact), high-viscosity oil (poor fluidity, difficult to penetrate into the tiny gap between the bearing raceway and the rolling element), or failure to use 'extreme pressure anti-wear gear oil' (hard-tooth surface reducer load is large, ordinary lubricating oil is easily crushed, and cannot form an effective protective film).
Mixing oil types: When lubricating oils of different brands, different base oils (mineral oil, synthetic oil) or different additive systems are mixed, chemical reactions may occur, resulting in a decrease in oil film strength, abnormal viscosity changes, and even sludge blocking the lubrication channels.
Deterioration of lubricating oil quality
Oxidative deterioration: Long-term high temperature (the bearing temperature is usually 40-80°C when the reducer is running, overloading or poor heat dissipation will cause over-temperature) causes the lubricating oil to oxidize, generating acidic substances and sludge, which not only reduces lubricity, but also corrodes the metal surface of the bearing.
Excessive pollution: External impurities (dust, metal scraps) or internal pollutants (iron filings produced by gear wear, particles from initial bearing wear) are mixed into the oil, which will destroy the continuity of the oil film and accelerate the abrasive wear of the bearing raceways and rolling elements, forming a vicious cycle of 'pollution - wear - more serious pollution'.
Water intrusion: Water intrusion into the oil (such as rainwater infiltration due to reducer seal failure, cooling system leakage) will emulsify the oil film, lose its lubrication ability, and may also cause bearing corrosion (especially bearing steel materials are prone to rust in humid environments).
2. Lubrication system/structural design or cause of failure
Abnormalities in the reducer's lubrication system (such as oil bath lubrication, splash lubrication, forced lubrication) or related structures may cause the oil to fail to effectively reach the bearings:
Oil level problem under oil bath lubrication method
The oil level is too low: If the F97 series reducer adopts oil bath lubrication (the bearing is partially or completely immersed in oil), the oil level does not reach the 'minimum oil level line' specified in the manual, and the bearing rolling elements cannot fully soak up the oil, resulting in insufficient lubrication.
Oil level is too high: Although there is sufficient oil, an excessively high oil level will increase the rotational resistance of the bearing, lead to increased friction and heat generation, and in turn accelerate the oxidation of the oil. At the same time, the oil may be violently stirred to produce foam (foam cannot form a stable oil film).
The lubrication channel is clogged or has a design defect
Channel blockage: If forced lubrication (such as oil pump supply) is used, or the bearing seat is designed with a special lubricating oil channel, sludge and metal debris may accumulate in the oil channel after long-term use, causing the oil to not flow smoothly into the bearing lubrication points.
Unreasonable channel design: For example, the oil channel aperture is too small, the angle is improper, or the oil port is not aligned with the 'load-bearing area' of the bearing raceway, resulting in the oil unable to accurately cover the key lubrication surface, resulting in local lubrication gaps.
Failure of splash lubricated 'splash parts'
Some reducers splash oil through gear rotation. If the top circle of the oil-splashing gear (such as a high-speed gear) is not immersed in oil, or the oil splash plate (if any) is deformed or falls off, the oil cannot be splashed into the oil groove/oil passage of the bearing seat, resulting in a lack of oil in the bearing.
