ENERGY EFFICIENT BEARING DEVELOPMENT PROJECT
Aim of this project is to; decrease the friction losses in to minimum level, by decreasing the friction torque values of the bearings.
In the content of this project, three key factors are identified that affects the friction torque.
These factors are:
- Special internal design of bearing
- Low friction grease
- Special cage design
In order to see the results of new designs and define the proper grease, different kinds of specimens were prepared and friction torque tests are performed. Results were compared and analyzed according to tests and proper grease is defined. Also the effects of the cage and internal design improvements on the friction torque was seen.
INTERNAL DESIGN OF BEARING
Internal design of the bearing is improved in order to decrease the friction losses. To see the effect of the design change, 6205 bearing specimens were prepared with G131 grease. With these specimens friction torque test was performed.
Graph 1: 6205 Bearing Internal Design Comparison Tests
|Ranking||Bearing Type||Mean of the Friction Torque Values|
|6205 EV1 G131 (Energy Efficient Bearing)||0.025092 Nm|
|6205 G131 (Standard Bearing)|
Low friction grease proposals were investigated from different grease suppliers. With these proposed low friction greases, 6205 bearing test specimens were prepared. Energy efficient bearing of a competitor’s also included to the comparison tests.
Graph 2. Grease Comparison test of 6205 Bearing.
|Ranking||Grease Code||Grease Name||Mean of the Friction Torque Value|
|1||G169||Klueber Isoflex Topas L32||0.001569 Nm|
|2||G27||Kyodo Yushi Multemp SRL||0.002180 Nm|
|3||GN79||Opet Fuchs Renolit WTF 2 B||0.002418 Nm|
|4||GN75||Shell Gadus S5 V25Q 2.5||0.002617 Nm|
|5||—||Competitor’s energy efficient bearing||0.004809 Nm|
|6||GN73||Molykote BG 555||0.005824 Nm|
Best result was achieved with Klüber; Isoflex Topas L 32 grease which can also be seen from above graph. Moreover, better results were seen according to the competitor bearing.
For decreasing the friction level further, cage design was also improved to decrease the friction region between cage pocket and ball. Cage weight was also decreased with new design, thus centrifugal effects at high speeds reduced. Strength of cage was decreased with decrease in weight. Because of this reason, material is changed to increase strength. Standard type TN1 cage and energy efficient TH2 cage were tested in 6306 EV1 bearing in order to compare friction torque.
Graph 3. Cage Design Comparison Test of 6306 EV1 Bearing.
|Ranking||Bearing Type||Cage Type||Mean of the Friction Torque Values|
After the tests, it was seen that, newly designed cage (TH2) is efficient in decreasing the friction torque of the bearing.
In the aim of increasing the energy efficiency of a bearing by decreasing its friction torque, different design improvements and tests were performed. According to this:
- Best friction torque value is achieved with Klüber; Isoflex Topas L 32 (G169). So, Klüber grease is selected as the grease of energy efficient bearings.
- According to test results, better friction torque results were achieved with improved internal design. With higher loads this improvement will show better results.
- TH2 cage, which is designed for decreasing the friction losses, is successful in 6306 bearing. During tests it was noted that new cage design is much more effective in larger bearing sizes and high speed applications.
- ORS EV1 energy efficient bearing and competitor’s energy efficient bearing friction torque test results are compared and ORS EV1 bearings have lower friction torque values rather than competitor energy efficient bearings.