“Voxel-Scale Characterization of Photopolymer Additive Manufacturing”

ABSTRACT:

Additive manufacturing (AM) promises disruption of traditional manufacturing supply chains, democratizing and distributing manufacturing, enhancing flexibility and enabling previously impossible geometries and customization. Applications range from aerospace to regenerative medicine, leveraging the numerous benefits of the technology. Within polymer AM, vat photopolymerization, enabled by advances in high-resolution display technologies (e.g. liquid crystal display - LCD, digital light processing - DLP) to locally cure liquid resin into solid polymer, prints millions of voxels per layer simultaneously in a few seconds or less. Typically, these layers are combined step-wise until a 3-dimensional part is formed. Fundamental understanding and control of the printing process with geometrically and mechanically precise voxels requires characterization of printer hardware and resultant parts at sub-pixel or sub-voxel length scales. Despite the advanced light engines, resultant parts exhibit defects such as over/under-polymerization, 3-dimensional anisotropy, weakened layer interfaces and more. In this presentation, we examine the formation of these defects starting from the individual light-pixels in the printer, through to the liquid resin and eventually solid parts. We introduce novel, multiscale measurement tools that elucidate the small-scale printing process in both space and time. The novel characterizations are used to develop new models of the printing process and enable precise geometric and mechanical control of the individual voxels. 

BIOGRAPHY:

Dr. Jason P. Killgore is the co-leader of the Photopolymer Additive Manufacturing project and leader of the Scanning Probe Microscopy for Advanced Materials and Processes project in the Applied Chemicals and Materials Division at the National Institute of Standards and Technology in Boulder, CO. He is a co-founder of the Photopolymer Additive Manufacturing Alliance and leader of the Materials Characterization Committee which seeks to engage industry stakeholders to prioritize relevant research topics. His research interests range from development of novel measurements, design of new printing materials and processes and implementation of industrial standards. Jason received his Ph.D. from the University of Washington Department of Chemical Engineering and joined NIST as a National Research Council fellow in 2009. Jason was a recipient of the 2018 NIST Bronze Medal award for the development of nanoscale viscoelastic measurements and the 2019 NIST Distinguished Mentoring Award. He has served as adviser and mentor to 6 national research council postdoctoral fellows and numerous graduate students.