Lubrication

Additive manufacturing to be showcased at lubrication conference

Tribologists and lubrication experts to gather online for STLE’s virtual annual meeting & exhibition.

By Michael Khonsari, Min Zou, Robert Jackson May 14, 2021
Courtesy: National Center for Additive Manufacturing Excellence (NCAME) at Auburn University

Additive manufacturing (AM) is an enabling technology for the rapid fabrication of parts with complex geometries that cannot easily be manufactured with traditional methods. While originally limited to rapid prototyping, recent advances in AM technology also enable direct fabrication of functional end-use parts in aerospace, medical devices, and military applications. However, the transition from rapid prototyping to fabricating end-use parts has also revealed technology barriers, including surface quality, accuracy, part variability, and uncertainty about the process-structure-property relationship, to only name a few. Crucially, fundamental questions about friction, wear, and lubrication of AM parts have led to substantial research interest in the tribology community.

Figure 1. caption: Surface topography from nature can be imaged at a high resolution and converted to CAD file for 3D printing, which directly replicate those surfaces for tribological and other applications. For example, replicated banana peel textures show low friction properties. This approach also enables bioinspired surface topographies to be designed and printed to realize targeted surface properties. (Courtesy: Prof. Min Zou at the University of Arkansas)

Figure 1. caption: Surface topography from nature can be imaged at a high resolution and converted to CAD file for 3D printing, which directly replicate those surfaces for tribological and other applications. For example, replicated banana peel textures show low friction properties. This approach also enables bioinspired surface topographies to be designed and printed to realize targeted surface properties. (Courtesy: Prof. Min Zou at the University of Arkansas)

AM should not be confused with the manufacturing of additives for lubricants. Nonetheless, additive manufacturing will have an impact on the field of tribology, and tribological analysis will be integral to evaluating additively manufactured (AM) materials for use in machine contacts.

Photo 1. A laser sintering raw powder in an additive manufacturing process.

Photo 1. A laser sintering raw powder in an additive manufacturing process.

The area of AM and tribology can be divided into two approaches: (1.) the characterization of friction and wear properties of additively manufactured materials and how they might differ from conventionally manufactured materials, and (2.) the employment of AM to provide new solutions to tribological applications. In the first, additively manufactured materials have already been shown to have bulk elastic and plastic material properties on par with conventional materials. However, their fatigue properties are often not as good due to voids and lack of fusion in between the raw material. Therefore, AM material might also show surface fatigue properties below that achieved by conventional processes. If not addressed, this could cause problems in applications such as rolling element bearings and gears. Additively manufactured parts also often possess a surface roughness that is inadequate for tribological applications. This means surface finishing is usually required.

Photo 2. Structures printed from the laser sintering additive manufacturing process

Photo 2. Structures printed from the laser sintering additive manufacturing process

AM also presents a tool to design new advanced tribological surfaces. This may include designing bio-inspired surface geometries into the surfaces. AM surfaces could also be made that are composites and made of several different materials printed together. AM may also provide a technique to add wear-resistant and friction reduction materials to an existing surface or perhaps even repair a surface damaged by wear.

A number of leading tribologists are convening in a virtual conference hosted by the Society of Tribologists and Lubrication Engineers (STLE), May 17-20, 2021, to highlight recent advances of tribology research related to AM, defining the state-of-the-art of tribology knowledge, and framing the challenges and opportunities for future tribology research in this exciting field.

Photo 3. Complex lattice structures printed from the laser sintering additive manufacturing process. Courtesy: National Center for Additive Manufacturing Excellence (NCAME) at Auburn University

Photo 3. Complex lattice structures printed from the laser sintering additive manufacturing process. Courtesy: National Center for Additive Manufacturing Excellence (NCAME) at Auburn University

 

Several sessions are dedicated to additive manufacturing research and development topics. Also showcased are two keynote presentations by leading authorities in the AM field. On Tuesday, May 18, from 8:30 to 10 a.m. EDT, Dr. Melissa Orme, vice president of Boeing Additive Manufacturing, will discuss advancements in the AM modality of powder-bed laser fusion and will present two case studies where we have realized added value in converting traditionally manufactured parts to additively manufactured parts. In addition, on Thursday, May 20, from 8:30 to 10 a.m. EDT, Dr. Christopher Williams, professor of mechanical engineering at Virginia Tech and the director of the Design, Research, and Education for Additive Manufacturing Systems (DREAMS) Laboratory, will provide an overview of the current challenges and opportunities in additive manufacturing. The presentation will include a range of opportunities for STLE expertise to engage and improve AM technologies and applications – spanning from characterizing and improving surface finish of printed metals to tuning the tribological performance.

The STLE Virtual Annual Meeting & Exhibition is the lubrication industry’s most respected event for technical information, professional development and international networking opportunities. For a complete listing of technical sessions, click here.

Michael Khonsari is the Dow Chemical Endowed Chair and professor of mechanical engineering at Louisiana State University.

Min Zou is Twenty-First Century Chair of Materials, Manufacturing, and Integrated Systems and professor of mechanical engineering at the University of Arkansas.

Robert Jackson is professor of mechanical engineering and director of the Auburn University Tribology Minor Program.


Michael Khonsari, Min Zou, Robert Jackson
Author Bio: Michael Khonsari is the Dow Chemical Endowed Chair and professor of mechanical engineering at Louisiana State University. Min Zou is Twenty-First Century Chair of Materials, Manufacturing, and Integrated Systems and professor of mechanical engineering at the University of Arkansas. Robert Jackson is professor of mechanical engineering and director of the Auburn University Tribology Minor Program.