NSK Develops World's First Highly Accurate Bearing Life Prediction Method Applying Ultrasonic Testing – Increases Basic Dynamic Load Rating of NSK Rolling Bearings

<p style="text-align: center;"><img src="/ueditor/php/upload/image/20230330/1680160669328332.png" title="1680160669328332.png" alt="2.png"/></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">NSK has developed the world&#39;s first high accuracy method for predicting the life of&nbsp;<a href="https://www.wswbearings.com/products/catalogue.html" target="_blank"><strong>steel rolling bearings</strong></a> based on statistical data of non-metallic inclusions in the steel from ultrasonic testing. Non-metallic inclusions are typically the origin of rolling contact (flaking) fatigue.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">This development has enabled NSK to revise up the basic dynamic load rating of applicable products to up to double the equivalent rolling contact fatigue life.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">This technology contributes to carbon-neutrality by enabling a reduction in the frequency of component replacement and machine maintenance and also enabling downsizing of machinery.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">NSK Ltd. has developed the world&#39;s first method to highly accurately predict the life of a rolling bearing based on statistical data (size and quantity) of non-metallic inclusions (impurities) in the steel.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">This technology has enabled NSK to revise up the basic dynamic load rating of its bearings and further enables customers to design machines and vehicles that make full use of the long-life performance of high-quality NSK bearings.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">NSK will initially begin to propose solutions based on this technology to select customers, followed by a broad revision of the basic dynamic load rating of its standard bearing lineup.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;"><br/></span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Background</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">NSK bearings are made of high-quality steel, which has been constantly improved by NSK researchers and engineers closely collaborating with steel manufacturers. As a result, the actual life of NSK bearings tends to be considerably longer than bearing life calculated in accordance with ISO standards.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">In order to better enable customers to make full use of the long-life performance of NSK bearings in their machine design and pursue carbon neutrality, we needed a technology that could calculate rolling fatigue life with a high degree of accuracy.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;"><br/></span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Details</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">1. Advanced detection and analysis of non-metallic inclusions using Micro Ultrasonic Testing Method (Micro-UT Method)</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">The rolling contact fatigue life of bearings is closely related to the size and quantity of non-metallic inclusions in the steel. Depending on the steel, the amount and distribution of non-metallic inclusions can vary widely.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">NSK&#39;s unique Micro-UT Method*1&nbsp;can inspect a volume of steel 3,000 times larger in one-fifth of the time compared to conventional methods*2. This enables efficient collection and analysis of highly reliable statistical data on non-metallic inclusions in bearing steel.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">2. NSK Digital Twin technology used to establish rolling bearing life calculation method based on non-metallic inclusion size.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">To derive a bearing life calculation method based on the analysis of non-metallic inclusions, NSK developed a unique rotational testing method that involves introducing artificial defects simulating non-metallic inclusions of various sizes into rolling bearing raceways.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">We succeeded in reproducing specific modes of failure as intended and further created a simulation*3&nbsp;capable of reproducing and analyzing the stresses around the artificial defects to futher clarify the mechanism of flaking fatigue.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Based on this we sucessfully developed the world&#39;s first*4&nbsp;method for calculating rolling contact fatigue life based on the size of non-metallic inclusions in steel.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;"><br/></span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Benefits</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Highly accurate bearing life prediction using NSK&#39;s Micro-UT Method enables the long-life performance of NSK bearings to be calculated more accurately than before. This calculation method is applied to revise up the basic dynamic load rating of bearings, which is a vital parameter used in application life calculation. For example, for radial roller bearings, it is possible to revise up the basic dynamic load rating to double the equivalent rolling contact fatigue life.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Revised basic dynamic load ratings open up new possibilities for customers that want to capitalize on the long-life performance of NSK bearings in their machine design. This is expected to help customers reduce the frequency of component replacement and machine maintenance and potentially downsize machine and unit designs, thereby contributing to the realization of a carbon-neutral society.</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;"><br/></span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">Notes</span></p><p><span style="font-family: arial, helvetica, sans-serif; font-size: 12px; text-align: justify;">*1: Micro-UT Method: Non-destructive testing using ultrasonic waves</span><br/></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">*2: Compared to NSK&#39;s conventional analysis method</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">*3: Created through an open innovation project with Professor Hisao Matsunaga, Kyushu University</span></p><p style="text-align: justify;"><span style="font-family: arial, helvetica, sans-serif; font-size: 12px;">*4: Based on NSK examination of available literature</span></p><p><br/></p>