Design and experimentation of a tribometer for non-lubricating fluid studies in journal bearing applications

Friction and wear phenomena are considered nowadays a strategic research topic for European Union' sustainability goals: in fact, recent studies estimate a potential saving up to 24% of primary energy consumption derived through tribological improvements 1 . Within the vast field of tribology of shaft-journal bearing systems, mechanics in non-lubricating fluid environments still represents a partially unexplored scientific area. Many industrial sectors are affected by the need of transporting and storing non-lubricating fluids, adopting mechanical technologies that often turn out to be inadequate for this purpose. Wrong materials choice and unbalanced working conditions not only lead to short working life of many mechanical components, but also force users to adopt inefficient technologies to face industrial challenges. This scenario even worsen when non-lubricating fluids contain solid particles, which can result in abrasive agents towards materials. The present study is based on an industrial problem to analyze this engineering issue. An innovative custom tribometer is proposed in order to simulate the behavior of different materials, treatments and coatings for shaft and journal bearing in non-lubricating environments. The instrument is designed to operate under high rotational speeds, heavy radial loads, and fixed operative temperature. A statistical approach is proposed to correlate torque and heat outputs with operating parameters, according to models proposed in previous literature. 2