Optical Metrology For Advanced Manufacturing II

Optical Metrology For Advanced Manufacturing II

PROJECT NUMBER: 87 | AUTHOR: Morgan Trexler​, Mechanical Engineering

MENTOR: Jeff Squier, Physics

ABSTRACT

Current additive manufacturing (AM) techniques struggle to provide feedback on part quality in-situ. As a result, AM parts require extensive post-process testing for certification. In laser-based AM processes, a 200+ watt laser melts metal powders at the fusion surface. Rapid thermal differentials cause defects in the part, such as porosity and warping. Our goal is to create a feedback system that determines characteristic interactions in-situ for optimizing print quality in real-time. Understanding the thermal structure of the part could provide means of understanding the fusion interaction. Thermal information at every point in the part is encoded by black body radiation. However, extracting the black body spectrum via traditional thermal imaging is challenging because of the high measurement speeds required in AM. We propose multiwavelength passive Spatial Frequency Modulated Imaging (SPIFI) as a possible solution for determining the thermal topography at the fusion surface. Thermal information would be collected along a line cursor and modulated by a SPIFI mask. The wavelengths of the modulated spectrum could then be split into multiple detectors where the ratio of incoming wavelengths can be compared for each location on the line cursor. Such an approach avoids the high costs and low resolution of ultrafast 2D camera-based thermal imaging. By providing more extensive feedback during the printing process, multiwavelength passive SPIFI could eventually detect printing failures and part properties minimizing optimization times for quality control.

PRESENTATION

AUTHOR BIOGRAPHY

Morgan is a junior in mechanical engineering with a passion for 3D printing. During high school, he built a 3D printer from scratch to be able to manufacture files he designed but he also really enjoyed understanding the printing process. When he came to Mines, he sought out opportunities to research with metal 3D printing, finding Jeff Squier from the physics department. Morgan has played a crucial role in researching metal 3D printing feedback technologies at Mines. One day he hopes to be able to integrate the techniques he is developing into commercial metal 3D printing.