Life Test

Fig. on the left shows a crank-driven type, rated life test device for linear motion bearings. The bearings were mounted on the device, then made to break down under 120kgf of a bearing load with a drip feed lubrication of machine oil.
Each group of sixteen bearings presented a test result as shown in Table 1.

n the life test, a total of eight bearings, or five groups of sixteen bearings, were made to break down.
Each group in the table shows differences in travel distance between the first broken bearing and the last one.
The average values of five tests, and their subsequent plotting on a Weibull chart, are presented in Fig2.
The figure indicates the presence of a minimum life. for the linear motion ball bearings.
Furthermore, the distribution of bearing’s life, taking the minimum life into account, is found to be nearly equal to a Weibull slope, e=10/9.
Thus the average life Ozak linear motion ball bearings with the breakdown probability of F=50% proves to be about 430 km, representing extremely high dependability.

Also the reliability of Ozak linear motion ball bearings stands at 0.4, which means our product in use are guaranteed 100% reliable until they reach 0.4 times the amount of rated life.
In order to further increase the life of the bearing, Ozak has conducted many experiments.
The methods established in our R&D department are currently under patent application.

・Test Results