NSK Technical Review (the former NSK Technical Journal)

NSK Technical Review introduces cutting-edge R&D activities and new products. (Past NSK Technical Journal also remain available bellow.)

Technical explanation

March 2026

No.2607　Gear Fault Diagnosis AI for Efficient Operation of Rotating Machines: A Physics-informed Approach

Inside rotating machines such as wind turbines, not only rolling bearings but also gears continue to rotate without rest. If gear damage occurs and the rotating machine keeps operating without anyone noticing it, the damage can lead to sudden shutdowns and severe consequences. However, when operating conditions such as the rotational shaft speed change, the vibrational characteristics of gears also change. Under such conditions, conventional vibration-based and AI-based diagnostics have sometimes struggled to make reliable decisions. NSK therefore studied an AI model that also learns the physical phenomena underlying vibration signals and examined whether it can stably diagnose gear damage even under previously unseen operating conditions.

March 2026

No.2606　Foundational development, modeling and configuration of state stabilizing mechanism to maintain axial tension in ball screw feed drive systems

This study presents a state stabilizing mechanism (SSM) that can maintain consistent axial tension in ball screw feed drive systems, even when the screw shaft is elongated due to thermal expansion. Hydraulic fluid sealed within a pressurized chamber expands from the intrinsic heat generated by bearing rotation, allowing the unit to autonomously maintain stable axial tension. Model calculations and experimental results have demonstrated the functionality of the mechanism and validate it as a solution that may be considered during design and specification review. The SSM is planned for incorporation in future products as the “NSK Feed Drive Adjuster.”

The article below was originally published in an academic journal of the Japan Society of Mechanical Engineers. It has been reproduced here with permission.

March 2026

No.2603　Lubrication Life Formula(Lubrication Pentagon Theory)

To achieve both further reduction in torque and extended life of bearings, we are working on deriving a lubrication life formula. This effort involves using five predictive formulas based on the Lubrication Pentagon Theory to forecast lubrication life, with the expectation of theoretically optimizing bearing performance. Additionally, we are making efforts to enhance the accuracy of the lubrication life formula by utilizing NSK's original visualization techniques.

March 2026

No.2601　Establishing a Spalling Life Prediction Method for Rolling Bearings utilizing “NSK Micro-UT™”

A highly accurate method for predicting Weibull plots of the spalling life of rolling bearings has been established using NSK's original steel cleanliness evaluation method, NSK Micro-UT™, and a life calculation formula derived from a new theory. This method supports the design and selection of more appropriate rolling bearings and can contribute to the realization of safety, security, and carbon neutrality.

New product introduction

March 2026

No.2609　Highly Reliable Spherical Roller Bearings for Wind Turbine Main Shafts

NSK has developed a high-reliability spherical roller bearing for wind turbine main shafts. This newly developed product has high load capacity enabled by a new type of cage and high raceway wear resistance achieved through NSK's proprietary materials, heat treatment, and high-hardness coating technology. By applying these technologies, the bearing life is approximately 1.3 times longer than that of standard products, and the amount of wear is reduced to less than one‑tenth. Sales of this developed product have commenced, primarily targeting the North American aftermarket. NSK will continue to contribute to the stable operation of wind turbines through sales expansion.

March 2026

No.2608　Low-Friction Hub Unit Bearing

HUB unit bearings support the vehicle body and enable smooth rotation of the wheels, and reducing friction in these bearings is expected to improve fuel efficiency. In addition, because HUB unit bearings are installed close to the tires, they are exposed to harsh operating environments, such as muddy water splashed up during driving, and therefore require high resistance to muddy water ingress. NSK has developed a new seal technology that combines low friction with excellent resistance to muddy water, achieving a significant 40% reduction in friction compared with conventional products.

March 2026

No.2605　Development of Bearings for Gas Turbine Generators for eVTOL (Large Drones)

To extend the cruising range of eVTOL aircraft, a range extender is essential to overcome the limitations of battery capacity. For gas turbine generators—considered the most realistic solution—we have developed a dedicated bearing equipped with a new, versatile lubrication mechanism capable of achieving rotational performance exceeding dmn 2.5 million.

March 2026

No.2604　Compact, Lightweight Deep Groove Ball Bearing for Electric Vehicles

To extend the driving range of electric vehicles, deep groove ball bearings for drive units must be compact, lightweight, narrow in width, low in friction, and capable of high-speed operation. NSK has developed a new deep groove ball bearing using a narrow width combined plastic cage. By integrating this cage with existing technologies, the bearing achieves significant reductions in size and weight, along with low friction and high-speed performance.

March 2026

No.2602　Extending the Basic Rated Life (Calculated Life) of Rolling Bearings: Practical Application of “High-Precision Life Prediction Using NSK Micro-UT™”Enhances Basic Dynamic Load Ratings of Rolling Bearings

NSK has developed the world's first method for accurately predicting the rolling contact fatigue life of common steel rolling bearings based on statistical data of non-metallic inclusions in steel using the ultrasonic flaw detection method.

This development enables NSK to improve the basic dynamic load rating up to twice as much as the rolling contact fatigue life, thereby reducing the frequency of parts replacement and machine maintenance and enabling downsizing of machines, thereby contributing to carbon neutrality.

＜Past NSK Technical Journal are available here.＞