Voices in the US. 

As tribology challenges move beyond the limits of standardised tests, particularly in areas such as electrification, alternative fuels, and demanding industrial systems, designing tests around real operating conditions has become critical. Dr Peter Lee is an Institute Engineer and Chief Tribologist in Tribology Research and Evaluations at Southwest Research Institute in the United States, and an Adjunct Professor at Texas A&M University. In this Q&A, Peter shares his perspective on why conventional testing often falls short, how experimental tribology should be approached in practice, and what capabilities testing instrumentation needs to keep pace with emerging applications. 

You’ve worked with PCS Instruments across a range of projects at Southwest Research Institute. From your perspective, how has PCS influenced the way your team approaches tribology problem solving for industry clients? 

PCS is a very responsive partner, as are some other rig manufacturers, in helping us adapt your rigs or add additional features or change safety limits in the software. We take a client’s individual problem and then look at which test rigs are available both in house and from rig manufacturers and select the rig that is going to be the best fit for finding a solution.  Sometimes these rigs have not been available, and one example of PCS’s response to our enquiry is the collaborative work with developing the MTM-EC. 

You’ve spoken previously about the limitations of relying purely on standardised tests. How do you think experimental tribology testing should be designed and implemented to better reflect real operating conditions in practice? 

The friction, wear and failure mechanism seen in the bench test has to be the same as that seen in the real application.  If that is not the case – the test is wrong – and will give misleading results at best. Therefore, before a bench test is designed, what is happening in the real application must be fully understood. Only then is it possible to begin considering how and if it can be modelled. In the tribology world, this process is rarely undertaken effectively and often the resulting test is further compromised to fit a test rig readily available in the labs. This approach wastes resources. For a test rig to give meaningful results, the test must give the same wear and friction as the real system.  Only when it is the same, can the test be used to find a problem solution or improvement for the real application. This involves four distinct steps, all of which must be done correctly – understanding the real system – designing a test that will replicate that system – undertaking that test on the correct tribometer – interpreting the results correctly and accepting any limitations. 

As tribology challenges evolve in areas such as electrification, alternative fuels and new materials, what role do you see advanced experimental testing playing in keeping research and industry aligned? 

Advanced experimental testing is essential for industry to be competitive, responsive and cost conscious. Therefore, as new technologies evolve, testing capabilities need to keep pace. If it is not possible to effectively test electrification or ammonia, for example, when the research tools don’t exist and the work cannot be done. This is why rig manufacturers are developing electrified, pressurised and high-speed versions of their test rigs and new test rigs are being developed. The research community, both those in industry and academia, needs to be vocal about their needs. Without this communication, rig manufacturers are less aware of upcoming requirements and where they should focus their development efforts. Once the rigs exist, then the research needed by industry can be undertaken. Currently, I would say that the advanced experimental testing for real applications is noticeably behind industry requirements. 

 
Looking ahead, what capabilities do you think tribology instrumentation needs to offer to keep pace with the demands you’re seeing from applied research and industry in the US? 

We are currently seeing a lot of space, nuclear and alternative fuel research. 

Space requires rigs that can operate under vacuum. But there are limited options available, and hence replicating the real application accurately can be challenging or impossible.  It is not possible to simply place an entire test rig in a vacuum chamber, as problems with circuit board and component cooling occur due to lack of air! In some circumstances the vacuum is not needed, and dry nitrogen can be used, but this still requires a sealed chamber from which friction results are desired. A full understanding of the dynamics of the rigs is required to ensure measurements are real and not artifacts of the rig design or alteration. 

Nuclear testing has involved different gases, such as argon, and friction and wear measurements at high temperatures and pressures. We have also been testing different material pairs at moderate temperatures with liquid salt under argon. No rig manufacturer currently makes an off the shelf rig that enables this testing and we have had to adapt and manufacture rigs to perform this work. 

Alternative fuel, such as hydrogen and ammonia, present their own challenges with rig design being as much about the health and safety of the testing as about the design of the tribometer. In these circumstances the rigs need to be designed and delivered, as much as is practically possible, with all health and safety requirements integral to the rig design. Obtaining friction results for alternative fuels can be challenging as it turns out internal test chamber strain gauges dissolve in the fuel and make great lubricity additives, whereas the alternative of measuring friction of the entire chamber response is not ideal either! 

Our latest round of patent applications have all been a result of finding novel ways to undertake testing requested by clients in the electrified, space, nuclear and alternative fuel areas. 

Outro 

Peter’s perspective highlights the growing disconnect between standardised testing and the realities of modern engineering systems. As industry requirements continue to evolve, progress increasingly depends on close collaboration between applied research organisations, industry, and instrumentation developers. PCS Instruments continues to engage with US-based research and evaluation teams to support testing approaches that better reflect real operating conditions and application-driven needs.