This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

The processes for manufacturing parts using additive manufacturing have meanwhile conquered a firm place in both the plastics and metal sectors. The processes usually work with a strong heat input, which can lead to distortion or shrinkage of the components. In order to calculate and compensate these undesired effects in advance, the finite element method is ideally suited, since multi physical simulations are now part of the standard equipment of software tools. Some experts therefore assume that the possibilities of simulation represent the next level of automation of additive manufacturing processes.



In the present paper, the possibilities have therefore been tested using a leading commercial tool. On different 3D metal parts, thermomechanical analysis as well as a purely mechanical analysis using a calibration part and the method of inherent strains were worked over. For thermomechanical analysis, approximately 60 different input values had to be determined, queried, calculated or simply guessed. In the purely mechanical analysis, only one real calibration part had to be created on the same printing machine with the same material and a deformation vector had to be measured during cutting.



The SLM (Selective Laser Melting) printed parts were precisely scanned and thus served as reference geometry for the deviations from the drawing geometry. The results from the process simulation - especially the distortions due to heat input - were compared with the deformations of SLM manufactured parts. There were hardly any differences between the results of the two simulation methods. The biggest differences were - of course - found during an additional investigation of the scanning directions and the position of the parts in the build-up chamber of the metal printer. The compensation of the distortion by the inversion of the calculated distortion resulted in a significant improvement of the distortion on the real parts, but led to rougher surfaces.



This first step into the simulation of the additive manufacturing process showed very encouraging results. Especially the method with a calibration part showed astonishingly good results and convinced with its advantages: reasonable computing times, independence from determination of the settings of the 3D-printing machine and powder quality as well as general practicability --> universality. Both methods have important advantages and disadvantages, which are compared here. From the findings of the present work, clear demands can be derived from the point of view of everyday users for the further development of the software tools.