Quiet Bearings Make for Quiet Electric Motors
MRO MagazineLubrication Transportation & Logistics
For long life and minimal motor noise, it is important to select a quiet bearing for electric motors. Today, electric motors function at increasingly higher speeds and higher operating temperatures, a...
For long life and minimal motor noise, it is important to select a quiet bearing for electric motors. Today, electric motors function at increasingly higher speeds and higher operating temperatures, and bearings must withstand the harsher operating conditions. NSK electric motor bearings are produced to high standards for quality, meeting or exceeding industry standards, which ensures extra-quiet ball bearings. NSK uses SUJ-2 steel for ball and ring assemblies. The steel is ultra-clean, vacuum-melted bearing steel, which is near aircraft quality, with oxygen content lower than 9 ppm. This nearly doubles the rated fatigue life of the bearings, resulting in long service life.
Smooth raceways also are important, since rough raceways inhibit lubrication and can lead to increased noise. At NSK, raceways are finished to a super-smooth condition, using a custom honing process. Surface finishes of less than a micron provide excellent lubrication and extend bearing life. Balls are made of high-grade steel. The two-piece riveted steel cages come with coined pockets for extremely close tolerances in the ball pocket. Friction is reduced by providing even distribution of the lubricant on the rolling elements. This means a strong cage with lower operating temperature an higher speed limits. The grease bears high-temperature, low-noise characteristics.
In the manufacturing process, NSK uses up-to-the-minute automated equipment to achieve consistency in every bearing it produces. At each step in the process, the company applies the latest Statistical Process Control techniques. Each assembled bearing is tested 100% twice for noise and vibration levels, using side-by-side anderometers in the manufacturing line. These instruments measure the degree of geometric and surface perfection and detect surface irregularities as small as one-millionth of a metre. Any bearing that does not pass low-, medium- and high-frequency vibration tests is rejected.