On the energy efficiency of pre-heating methods in SLM/SLS processes

Selective laser melting/sintering (SLM/SLS) are the most established metallic powder bed additive manufacturing (AM) processes. Pre-heating of the powder and the part in SLM/SLS is performed in order to minimize residual stresses and increase the quality of manufactured parts. However, pre-heating constitutes a large portion, in some cases up to 40%, of the total energy consumed for building a part with SLM/SLS. This paper presents an energy consumption evaluation and comparison of the three existing pre-heating methods in SLM/SLS, which are (i) build chamber pre-heating, (ii) base-plate heating and (iii) laser pre-scanning heating. In order to calculate the energy consumption, transient thermal modeling with the finite element method is performed for all the three methods. The thermal model is applied in the case of the fabrication of a twin cantilever beam made out of titanium alloy Ti6AlV4. In addition, the initial energy required to heat the base plate and the process chamber up to the target temperature are calculated. Results show that laser pre-scanning heating leads to lower heat consumption when it comes to low volume parts, i.e., low part to powder bed volume ratio. For fabricating a higher number of parts or parts of high volume, i.e., high part to powder bed volume ratio, the chamber pre-heating and the base plate pre-heating method are found to be more efficient.