ADVERTORIAL TECHNOLOGY IN ACTION Plain bearings – plain by
The problem often starts when a designer relies on the same bearing even though the application has evolved – the loads get bigger, the speeds get faster or another variable is introduced such as a change in chemical or the withdrawal of adequate lubrication or maintenance access. A bearing is a small part with a big responsibility and like all components, it has a limit; so the key is to respecify, rather than push the boundaries of the bearing you are used to using.
Specifying the right plain bearing
any specifiers fall into the trap of treating plain bearings as a commodity design element, opting for the same product time and time again, with no real regard to the application.
M
Here Paul Mitchell, managing director for Bowman International, explores the importance of correct specification when it comes to optimising performance and reducing both planned and emergency maintenance. With many more material and design options to choose from that one might expect, it could be said that plain bearings are plain by name but not by nature. For design engineers who work in a closed field specifying component parts for a specific environment, specifying plain bearings can become a tick-box exercise. However the same can’t be said for aggressive or unusual applications, where it is far more important to select your bearings on a project-by-project basis.
The guiding principal for an engineer is that the bearing is the wear element and therefore the shaft must be made of a harder material than the bearing. Knowing the shaft material and its performance properties before commencing bearing selection is crucial and combined with that all important consideration of cost, your manufacturer or distributor of choice will be able to assist you in making the right choice for each project. There are a huge number of variables at play when selecting the right bearing and if you are using a shaft which has not been rated by your bearing supplier, then many of the commonly used ‘lifetime calculations’ will still leave margin for error when it comes to marrying the right shaft with the right bearing.
One of the main parameters used in correct bearing specification is the
Pressure Velocity Ratio (PVR), the relationship between load and speed, which can give an indication of the wear that is likely. Like all lifetime calculations though, it doesn’t offer a complete picture, so further investigation into the load and speed is essential. The type of load, whether intermittent or continuous, and whether there is a shock load to consider are all important factors, as well as the coefficient of friction and the lubrication within the system.
Bearing manufacturers have invested heavily in research and development in recent years and we are really starting to see the benefit as an industry. New alloys have been introduced, along with new techniques for manufacturing, testing and fault analysis.
32 SEPTEMBER 2016 | DESIGN SOLUTIONS
/ DESIGNSOLUTIONS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
