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By Joshua Shenker
Are you familiar with the word tribology? After recently gaining a doctorate in the subject, I’ve spoken about it to people and have found just a small number nod in agreement, many more confuse it with the study of tribes, but most people are just outright confused. Yet even if you have never heard the word tribology before, it’s likely that you will know its subject matter, and as designers, product developers and engineers at CDP it’s increasingly relevant to our day-to-day work for our clients.
Tribology in its broadest definition is the science of interacting surfaces in relative motion, but the subject extends to the study and application of the principles of friction, wear and lubrication. It can therefore be considered a fundamental science spanning many disciplines including physics, chemistry, engineering and material science. Historically tribology has been confined to the heavier industries such as transportation, power generation, mining and manufacturing, but as technology progressed over time, the subject spilled over into new research areas and industries.
More recently, tribological research has found its way into the development of products stretching from specialist medical environments through to every-day use consumer markets. But how can studying gecko’s feet or a lotus leaf help with the design of products?
Whilst the term tribology is a fairly recent invention, its subject matter can be traced back to some of the earliest civilisations including the ancient Egyptians and Mesopotamians. There are several examples of tribological devices scattered through history involving rudimentary bearings and manually lubricated surfaces such as potter’s wheels, hinged doors and wheeled carriages.
Yet the word only really came into the public consciousness in 1966 when a UK Government committee published what is now commonly referred to as the Jost Report. It aimed to demonstrate the potential savings to industry if greater attention were paid to tribological design. Put simply, by making equipment more efficient or less prone to wear, long-term financial savings could be made in almost every industry sector by reducing maintenance costs and increasing productivity. The report quantified these combined costs in lost earnings to the UK economy, estimated in 1966 to be around £515 Million annually (£8.6 Billion in today’s money). And so, I recently attended the 50th anniversary event of the Jost Report to hear about new developments in tribological research since finishing my studies and to identify areas of interest and relevance with our work at CDP.
One interesting emerging area of research is biotribology, the study of interacting surfaces in the natural world – in plants, the environment and people. Part of this research, biomechanics aims to understand how nature creates highly articulated joints that can be self-lubricating and thus limit levels of wear. It looks into how these systems can be replicated so that artificial implants can work seamlessly with the body. Indeed, 40% of all biotribology research focuses on artificial joints, implants and prosthetics. This in itself has opened up new branches of biotribology concerning the involvement of medical intervention, aiding the development of surgical instruments, medical therapies, medical devices and machinery.
Skin tribology is the second largest research area within biotribology. It focuses on elemental research on skin friction or synthetics, with a significant level of investment also going into researching skin contact with everyday items such as clothing, creams, cosmetics, shaving equipment, and even consumer products. A lot of research, both academic and within industry, is currently being done to understand and ensure that everyday products ‘feel’ acceptable to the consumer.
This highlighted to me the importance of being able to translate the qualitative language of what a consumer likes, into a quantitative way to test against. To quote Lord Kelvin: “If you cannot measure it, you cannot improve it.” Haptics, tactile perception and surface texture all contribute to what a consumer likes when they buy or use a product, whether they realise it or not. Therefore the importance of the tribologist cannot be underestimated in being able to translate what the consumer ‘feels’ to what can be designed, engineered and measured.
The third largest research area in biotribology is oral tribology, which goes further than oral care and hygiene for dentistry applications. A new area, oral processing, focuses on food technology, food rheology, ‘mouthfeel’ and taste perception, and examines how these parameters can be measured when developing ‘newer’ foods. A good example is chocolate, where it’s been found that consumers prefer the feel of smooth, low-viscosity melted chocolate. Sounds simple enough, but actually a tough order to fill in today’s mass manufactured world, especially with chocolate containing a complex array of particles and agglomerates, with non-homogenous properties both difficult to model and predict how they will interact. With the help of biotribology, the chocolatiers adjusted certain properties, including the inclusion of surfactants to prevent agglomeration and by refining the particles to no more than about 25 microns in diameter, so that the still solid chocolate would feel to consumers as though it were ‘liquid smooth’.
The list of areas within biotribology that are yielding interesting findings goes on, including biomimetics, which looks at nature for the development of bio-lubricants, smart fluids, or new materials with specific surface textures and chemistries. Novel research areas are looking into issues such as what causes a gecko’s feet to adhere so well to surfaces. Why is a shark’s skin more streamlined than that of other marine life? And why does water not stick to the leaf of a lotus flower? The implications of this kind of research allows for newer and greater improvements in a wide range of technology that is used extensively in different applications - whether it’s the latest sports equipment, fabrics, kitchenware or waterproof electronics.
Tribology is all around us naturally, and we benefit from it all the time, mostly unintentionally. With a greater appreciation of it as a science, and its occurrence in nature, gaining a better understanding of it can benefit us all in some shape or measure. So whether it’s the latest self-cleaning touchscreen device, or the newest non-stick household appliance, you have both nature and a tribologist to thank for that.
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