Development of a polygon mirror based SLA 3D-printer

Abstract

Additive manufacturing (AM) constantly gains in importance in the manufacturing industry. Compared to classical manufacturing technologies, it offers many advantages such as almost unlimited design freedom and affordable manufacturing even at low quantities. Furthermore, parts can be produced with minimum excessive material consumption compared to conventional manufacturing methods. This leads to a significantly reduced ecological footprint of AM. State of the art industrial printers, which achieve high resolution and accuracy, are based on the stereolithography (SLA) principle in combination with Galvanometer beam steering. Scanning speeds between 2 m/s and 30 m/s are typical and limited by the scanner dynamics, such that medium and large part counts are not economically achievable. By speeding up the manufacturing processes, this limitation can be circumvented, enabling additive mass production. With polygon mirrors (PMs), a laser line scan speed of a few hundred meters per second can be achieve. This work presents the design, control and evaluation of a polygon mirror based SLA 3D-printer. To compensate the imperfections of the PM the facet to facet and wobble error is determined. Prints of multiple test objects are performed to evaluate the achievable accuracy and surface finish. Finally, the performance is compared to a commercial LCD based SLA printer.