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An education in bearings - what does it translate to in the job market?

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An education in bearings - What does it translate to in the job market?

Part 1 of 2

Written by our guest Bearings Expert, Dave

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You will most certainly have come across bearings at some point in your engineering degree or other higher education program. It may have been a fleeting reference to them simply describing what they are and their function in the system, or you may have done some design or calculation involving bearings at some level.

Typically, in-depth training on bearings does not come as part of an educational curriculum, except for certain specialised courses, particularly those involving machine design, and mostly at masters level. I Myself had the good fortune of this on an MSc. course in Design of Rotating Machines, at Cranfield University in the UK. Here, I was assigned a project where I had to select appropriate bearings for a system being designed, determine their positioning along a shaft, analyse the force systems at play with them incorporated, along with other machine elements like gears, belt drives, etc.

Really specialised courses will let you in on a bit more of the science of bearings. These are programs which have a practical and industrial aspect to them, or those involving Tribology. A module in Tribology may be found as part of the curriculum in an engineering department where part of their research work is in this area. Cardiff and Leeds University and Imperial college in the UK are examples. South-Western University in (Texas) in the US is another. (If getting into such universities is not an option, alternative ways of educating yourself are discussed in Part 2 of this article). Again I was fortunate to go further in my education onto a PhD. at Cardiff where I did do research into tribology, and a module on the topic was taught to the graduate students there. My research was not specifically on bearings in particular though, but it did have to do with some sort of bearing interface. All the same, those educational experiences led me to most of my working career being on bearings, previously in the marine industry, and currently in the aerospace sector. In these industries, bearings are designed from scratch by themselves, and then sent to the bearing manufacturer to be made. So the first point to be aware of is that a career with an educational background giving a good foundation in bearings does not necessarily have to be with a bearing manufacturer.

So what is Tribology? Simply put, it is the science of interfaces. Where any two surfaces come into contact with each other, usually with some relative movement, tribology is involved. As we know, the bearing balls roll (sometimes slide) over the bearing rings. Even though there is an interposing fluid in between, it is still classed under tribology. We’ll come back to the reason why later.

So what is the focus for two mating surfaces coming together? Yes you guessed it - friction! Tribology is focused on the study of friction and wear between two mating parts. Hand in hand with friction comes wear. The cost of wear of machine or structural parts runs into millions of dollars per year. This cost comes in the form of maintenance, machine downtime, efforts to resolve amongst a host of other things. Lots of research goes into understanding these phenomena in order to alleviate these problems. Utilisation of specially fashioned materials and coatings and additives in lubricants are amongst the methods used.

Bearings are introduced into a mechanical system to allow a shaft to rotate, because of their low friction. However, because of the foregoing discussion, they themselves can suffer wear. The manufacturers have put a lot of effort into designing their bearings. Advances in materials technology has been a major contributor to improvement to bearings in perhaps the last 20 years or so.

I was recently involved in a task whereby some of the bearings used in the company’s machinery with older specification of materials had to be modified to have new bearing materials, as they were coming into service too often. This was not only accruing cost, but causing unnecessary service disruption. To my surprise, the task was not as simple as changing the material spec on the drawing and sending it to the shop floor to be made and fitted. Even though the advantages in material properties were obvious, it had to be taken through a design modification process as any other design activity and proven from every angle. Mistakes in design of a component can be even more costly than if it had been left as it is if every aspect that may affect it and the other components surrounding it in the system are not carefully considered.

The larger manufacturers have their own research technology centres where they are constantly trying to improve bearing technology. Bearing design itself is a fundamental science which has not changed for many decades. ISO280, which is a bearing international standard, has had very few minor updates since the 1980s. But with new applications and failure scenarios arising in recent times, they need to stay on top of their game! The main aim of this International Standard is to come up with a standardised method for calculating Load carrying capacity, and to specify the calculation method to determine Life ratings for bearings, so that users can know how long to run them for before replacing, and can plan their maintenance schedules. This is because bearings do not follow the general fatigue laws for life calculations, because of the complex physics involved (i.e. tribology discussed above), and lots of empirical factors from testing and experience need to be introduced.

As well as design, bearing dynamics is also paid a lot of attention to, particularly in high speed applications. At very high speed, centrifugal forces may distort the bearing components and lead to different behaviour to the design condition. The bearing cage is one aspect of bearings not really taken into account in the bearing design standards, and may be considered by a dynamic analysis. You may not have been exposed to this in an educational program, so it is good to be aware of. To note, systems where the bearings are on a shaft rotating at high speed are normally referred to as rotating machinery, although the term can be applied to slower moving machines as well. So anything from an aeroengine or high speed tool spindle, to a conveyor or cement mixer.

It is quite a lucrative industry, and there is a high demand there for people that have knowledge of bearings. As I mentioned, the course I took was specifically design of rotating machinery, to show that there is a real need for engineers in this area.

This brings us back to the topic - how does an education in bearings translate into the job market?

This article was written by our Bearings Expert Dave.