Real-time process control of powder bed fusion by monitoring dynamic temperature field

Abstract

This study aims to optimize the uniformity of the temperature field during sintering to improve part performance. A temperature-field monitoring system is established based on an infrared thermal imager and the temperature field data obtained during the sintering of a part can be measured in real time. The relationship among the sintering temperature field, sintering process parameters, and part performance is established experimentally. Subsequently, a temperature field monitoring and analysis system is constructed, and various sintering temperature-field control strategies are established for various part sizes. Finally, a dynamic control strategy for controlling the temperature field during sintering is proposed, experimentally validated, and fully integrated into a developed powder bed fusion (PBF) equipment. For eight-shaped standard parts, the range of sintering temperature field is optimized from 44.1 °C to 19.7 °C, whereas the tensile strength of the parts increased by 15.4%. For large-size H parts, localized over burning is eliminated and the final quality of the part is optimized. This strategy is critical for the optimization of the PBF process for large-sized parts, in particular in the large-sized die manufacturing industry, which offers promise in the optimization of part performance.

Keywords

Powder bed fusion (PBF) / Sintering temperature field / Monitoring system / Infrared thermal imager

References

[1] Bidare P, Bitharas I, Ward RM, et al. Laser powder bed fusion at sub-atmospheric pressures. Int J Mach Tools Manuf, 2018, 130/131: 65-72.

[2] Criales LE, Arısoy YM, Lane B, et al. Laser powder bed fusion of nickel alloy 625: experimental investigations of effects of process parameters on melt pool size and shape with spatter analysis. Int J Mach Tools Manuf, 2017, 121: 22-36.

[3] Josupeit S, Ordia L, Schmid H. Modelling of temperatures and heat flow within laser sintered part cakes. Addit Manuf, 2016, 12: 189-196.

[4] Ganci M, Zhu W, Buffa G, et al. A macroscale FEM-based approach for selective laser sintering of thermoplastics. Int J Adv Manuf Technol, 2017, 91: 3169-3180.

[5] Setti GDO, Lopes Da Silva JV, De Oliveira MF, et al. Surface methods for monitoring the densification of parts in the selective laser sintering process. Rapid Prototyp J, 2014, 20: 157-163.

[6] Bai J, Zhang B, Song J, et al. The effect of processing conditions on the mechanical properties of polyethylene produced by selective laser sintering. Polym Test, 2016, 52: 89-93.

[7] Song JL, Li YT, Deng QL, et al. Rapid prototyping manufacturing of silica sand patterns based on selective laser sintering. J Mater Process Technol, 2007, 187/188: 614-618.

[8] Brajlih T, Paulic M, Irgolic T, et al. Study of the complementary usages of selective laser sintering during the high volume production of plastic parts. Rapid Prototyp J, 2016, 22: 735-742.

[9] Van Hooreweder B, Kruth J. High cycle fatigue properties of selective laser sintered parts in polyamide 12. CIRP Ann Manuf Technol, 2014, 63: 241-244.

[10] Xing J, Sun W, Rana RS. 3D modeling and testing of transient temperature in selective laser sintering (SLS) process. Optik, 2013, 124: 301-304.

[11] Wegner A, Witt G (2011) Process monitoring in laser sintering using thermal imaging. In: The 22nd annual international solid freedom fabrication symposium-an additive manufacturing conference, Austin, TX

[12] Wegner A, Witt G (2015) Understanding the decisive thermal processes in laser sintering of polyamide 12. In: Proceedings of the polymer processing society 30th annual meeting, Cleveland, Ohio. https://doi.org/10.1063/1.4918511

[13] Wroe WW, Gladstone J, Phillips T, et al. In-situ thermal image correlation with mechanical properties of nylon-12 in SLS. Rapid Prototyp J, 2016, 22(5): 794-800.

[14] Abdelrahman M, Starr TL. Quality certification and control of polymer laser sintering: layerwise temperature monitoring using thermal imaging. Int J Adv Manuf Technol, 2016, 84: 831-842.

[15] Zeng K, Pal D, Stucker B (2012) A review of thermal analysis methods in laser sintering and selective laser melting. In: The 23rd annual international solid freeform fabrication symposium—an additive manufacturing conference, Austin, TX, pp 796–814

[16] Kim H, Lin Y, Tseng TB. A review on quality control in additive manufacturing. Rapid Prototyp J, 2018, 24: 645-669.

Funding

The National High Technology Research and Development Program of China (863 Program)(2015AA042503)