An effective method for large-scale temperature simulation in SLM based on the finite difference

Abstract

Numerical simulation is an effective approach to analyze the selective laser melting (SLM) process and reduce the production development cost. Based on the finite difference method (FDM), the nonuniform grid algorithm (NUGA) is developed to simulate the thermal behavior in SLM process concerning the variable thermophysical parameters of materials with different status. The NUGA can effectively improve computing efficiency, and the calculation speed using NUGA is 610 times than that without using NUGA. Different heat transfer strategies are used on each side of the two critical scanning speeds, 68.95 mm/s and 6895 mm/s, respectively, and the results of temperature calculations are highly consistent. The correctness of the heat transfer strategy under different speeds is analyzed using the NUGA. The effects of processing parameters (laser power, scanning speed and building height) on the shape and volume of the molten pool are investigated. As the scanning speed ranged from 100 mm/s to 500 mm/s, the width and depth of the molten pool decrease, while the length increases. As the laser power ranged from 100 W to 500 W, the length, width and depth of molten pool all increase. The length of the molten pool increases 11.68% from 264.94 of layer 1 to 295.88 of layer 5. The molten pool volume decreases, then increases and decreases finally from the start to the end of single molten path. The molten pool volume increases with increasing laser power and building height, while decreases with increasing scanning speed in general. The NUGA is an effective method for temperature simulation of large-size parts, which expands the application range of temperature simulation in SLM process.