Ningbo Kent Bearing Co., Ltd

For electric motor production and R&D, whining noise is not only a notorious "quality saboteur" but also a top pain point for most motor manufacturers. Drawing on decades of bearing technology expertise, I have identified that the root cause of the vast majority of motor whining noise issues lies in the selection and matching of bearings. Fix 1: Choose High-Precision Bearings to Suppress Whining at the Source One core cause of motor whining is insufficient bearing precision, which leads to excessively high friction-induced vibration frequencies between the raceways and steel balls during operation.Our high-precision ball bearings adopt nano-level super-finishing grinding technology, controlling radial runout within standard limits and significantly reducing vibration deviations during rotation. Coupled with an optimized raceway curvature design, they minimize high-frequency noise generated by frictional contact—cutting off the possibility of whining at the source. This is also the preferred solution for numerous motor manufacturers to resolve whining problems. Fix 2: Match Low-Friction Quiet Bearings to Suit Diverse Working Conditions Motors used in different application scenarios have varying bearing requirements; blindly using general-purpose bearings can easily trigger whining noise.For instance: Home appliance motors demand silent operation; Power tool motors need to withstand high-frequency start-stop cycles; New energy motors require high-temperature resistance. Our bearings are formulated with premium low-friction lubricants tailored to different motor working conditions. They not only reduce operational noise but also adapt to a wide temperature range of -20°C to 120°C. Furthermore, we offer customized adjustments based on customer-specific motor parameters such as power, rotational speed, and operating conditions, ensuring perfect compatibility between bearings and motors and eliminating whining caused by mismatched working conditions. Fix 3: Strictly Control Bearing Installation & Quality Assurance to Avoid Secondary Whining Even with the right bearings selected, improper installation or quality defects in the bearings themselves can still lead to whining noise.As a direct bearing manufacturer, every batch of our bearings undergoes 12 rigorous inspection procedures including dynamic noise testing and service life testing, ensuring zero quality defects before factory shipment. We also provide customers with professional installation guidelines to avoid issues such as coaxiality deviations and improper preload during assembly. This full-process support—from production to installation—helps manufacturers eliminate the risk of secondary whining noise. In short, there’s no need to worry about solving motor whining noise—the core lies in selecting the right bearings, achieving precise matching, and enforcing strict quality control. Ningbo Kent Bearing has provided over 200 million sets of silent bearing solutions to more than 500+ motor manufacturers worldwide. If your motors are plagued by whining noise issues, or if you want to avoid such problems proactively, feel free to contact the Kenda Technical Service Team at +86-19957028916. We will provide you with a free customized technical bearing selection plan, helping you completely eliminate whining noise troubles and enhance your product competitiveness!

  For motor manufacturers, the excessive friction in motor bearings is a pervasive pain point that impacts every stage of production and the market. Ordinary bearings with high friction resistance demand more electrical energy to overcome resistance during startup, leading to excessive energy consumption. This is particularly detrimental in sectors with stringent energy efficiency requirements, such as new energy vehicles and home appliances, where it can quickly erode competitiveness. Moreover, high friction accelerates wear between bearing raceways and rolling elements, increasing operational noise and shortening the lifespan of both the bearings and the entire motor, which directly drives up repair rates and after-sales costs. Most critically, the heat generated by friction can compromise the stability of internal motor components. In high-load, continuous operation scenarios like those found in garden tools and industrial motors, this can lead to overheating failures and a surge in customer complaints。   The motor bearings produced by Kent are specifically designed to address these pain points. Their core advantage stems from two key technological breakthroughs: first, the use of optimally designed rolling elements paired with micron-polished raceways to reduce the coefficient of friction, ensuring not only a "smooth and resistance-free" operation but also extending the motor's lifespan. Second, the application of a custom low-friction lubricant, which not only minimizes friction between contact surfaces but also maintains stable performance across a wide temperature range of -40°C to 180°C, adapting to various motor operating conditions. The value of low friction is immediately evident: it reduces motor energy consumption to meet efficiency certification standards, minimizes heat generation, significantly enhances operational stability, and reduces noise levels.   For motor manufacturers, selecting motor bearings is not just a "nice-to-have" but a critical factor in "cost reduction and efficiency improvement." It not only helps optimize product performance and create differentiated selling points but also indirectly saves significant costs by reducing energy consumption and minimizing returns. As a direct manufacturer, Kenda focuses on low-friction technology R&D from material selection to process optimization. We can precisely adjust bearing structures and lubrication solutions based on motor speed, load, operating environment, and other conditions, ensuring the low-friction advantage is perfectly tailored to your products.     

  Research shows that approximately 80% of premature bearing failures are due to incorrect installation. Proper bearing installation can not only extend bearing life and reduce costs, but also significantly improve production efficiency. Therefore, learning correct bearing installation knowledge is urgent.   Bearings are components used for support, specifically to support rotating parts on a shaft. By friction type, bearings are classified as sliding bearings and rolling bearings; by load direction, they include radial bearings, thrust bearings, and radial-thrust bearings. So how to install them correctly? ‌     Sliding Bearing Assembly‌       Sliding bearings are characterized by sliding friction, offering smooth operation, low noise, and the ability to withstand heavy loads and significant impact. They are classified into integral, split, and block types based on structural design.  ‌    1) Integral Sliding Bearing Assembly‌   Commonly called bushings, integral sliding bearings are the simplest form, primarily assembled via pressing or hammering. In special cases, thermal installation is used. Most bushings are made of copper or cast iron. Care is required during assembly: use a wooden hammer or a hammer with a wooden block for striking, or a press for larger interference fits. Tilting must be avoided, and oil grooves/holes must align precisely. Post-assembly, if deformation occurs, recondition the inner bore. Small bores are reamed, while larger ones are scraped. Maintain the shaft-bushing clearance within tolerance. To prevent rotation, install positioning pins or set screws on the contact surface. Due to material hardness differences, drilling may cause bit deflection. Solutions: Pre-punch hard material before drilling. Use a shorter drill bit to increase rigidity. ‌2) Assembly of Split Bearings‌ Split bearings, also known as two-piece bearings, are characterized by simple structure, convenient adjustment, and disassembly. Two bearing liners are inlaid on the bearing shell, and a reasonable clearance is adjusted with shims at the joint. ‌① Assembly of Bearing Liner and Bearing Body‌ The contact between the upper and lower bearing liners and the inner hole of the bearing body must be good. If it does not meet the requirements, use the inner hole of the bearing body of the thick-walled bearing liner as a benchmark, scrape the back of the bearing liner, and at the same time, the steps at both ends of the bearing liner should tightly against the ends of the bearing body. For thin-walled liners, it is sufficient that the split surface of the liner is about 0.1mm higher than the split surface of the bearing body, and scraping is not necessary. ‌② Installation of Bearing Liner in Bearing Body‌ The bearing liner installed in the bearing body is not allowed to have displacement either radially or axially. Usually, the steps at both ends of the bearing liner are used for positive positioning or positioning pins are used. ‌③ Fitting and Scraping of Bearing Liner‌ Split bearing liners are generally matched with their corresponding shaft for spotting. Usually, the lower liner is scraped first, then the upper liner. To improve efficiency, when scraping the lower liner, the upper bearing liner and cover may not be installed. When the contact points of the lower liner basically meet the requirements, then press the upper liner and upper cover tightly, and when scraping the upper liner, further correct the contact points of the lower liner. During fitting and scraping, the tightness of the shaft can be adjusted by changing the thickness of the shims as the number of scraping times increases. When the bearing cover is tightened, the shaft can rotate easily without significant clearance, and the contact points meet the requirements, indicating the fitting and scraping is completed. ‌④ Measurement of Bearing Clearance‌ The size of the bearing clearance can be adjusted by shims at the split surface, or obtained by directly scraping the bearing liner. The bearing clearance is usually measured by the lead wire compression method. Take several sections of lead wire with a diameter larger than the bearing clearance, place them on the journal and the split surface, then tighten the nuts to compress the split surface. Then unscrew the nuts, remove the bearing cover, carefully take out the flattened lead wires, measure the thickness of each section with a micrometer, and the bearing clearance can be known based on the average thickness of the lead wires. Generally, the bearing clearance should be 1.5‰-2.5‰ (mm) of the shaft diameter. When the diameter is large, a smaller clearance value is taken. For example, for a shaft diameter of 60mm, the bearing clearance should be between 0.09-0.15mm. ‌II. Assembly of Rolling Bearings‌ Rolling bearings offer advantages such as low friction, compact axial dimensions, easy replacement, and simple maintenance. ‌1) Technical Requirements for Assembly‌ ① The end face of the rolling bearing marked with a code should be installed in a visible direction for easy reference during replacement. ② The fillet radius at the shoulder of the shaft neck or housing hole must be smaller than the corresponding radius on the bearing. ③ After assembly, the bearing must not be skewed on the shaft or in the housing hole. ④ Among two bearings on the same shaft, one must allow axial movement during thermal expansion of the shaft. ⑤ Strictly prevent contaminants from entering the bearing during assembly. ⑥ After assembly, the bearing should operate flexibly with low noise, and the working temperature should generally not exceed 65°C.