Analysis of Quasi-Simulateneous Energy Deposition for Preheating Polymer Powders in the Simultaneous Laser Beam Melting Process

Motivation: Simultaneous Laser Beam Melting is a new Additive Manufacturing technology to build parts that consist of different materials. By the means of SLBM polymer powders with different properties are processed in order to achieve multi-material parts with different mechanical, optical, and chemical properties. The SLBM process is still on the basic research stage.
Until now, a lot of work have been done to optimize SLBM process and to study variety of the applicable polymers and their compatibility in simultaneous melting. Besides all that, the problem that limits the progress in the SLBM process is the fixed rectangular form of the built-up specimens. This is mainly because a DOE (diffractive optical element) was used to achieve a fixed form simultaneous laser energy deposition. This step of the process is essencial to compensate the preheating temperature difference between two polymers. Moreover due to the DOE usage the energy density over the region of interest was limited since the laser energy was spread over the entire surface through the DOE mask. This prevented the ability to compensate the high preheating temperature difference and thus limited the possible polymer combinations.
The aim of the project is to modify the CO2 radiation delivery system that will allow a preheating of the flexible shapes. Plus, it will allow the preheating of the polymer combinations with a big melting temperature difference. The aim of this modification is to obtain a homogeneous temperature distribution on the surface of the powder bed through quasi-simultaneous laser energy deposition with single defocused laser beam prior for melting. Therefore, a high speed galvanometric laser scanner is integrated and its operation is investigated. Moreover, the LabVIEW software program is developed for the synchronized control of the scanner and the CO2 laser during the process. Afterwards, the quasi-simultaneous energy deposition parameters are analyzed and optimized. Furthermore, the aim of this project is to use the quasi-simultaneous energy deposition method to try to compensate a preheating temperature difference in 60 K between polyamide based TPE and PA12 polymers. Therefore, required experiments are done. The analysis of the three-dimensional temperature field of the powder bed during the preheating stage of the process is delivered, using thermal camera system and thermocouples positioned inside the powder bed. The final objective of this study is to develop a process protocol to preheat the PA12 polymer powder in combination with polyamide based TPE using a quasi-simultaneous energy deposition.