The main challenge associated with the application of Selective Laser Melting (SLM) to Ni-based superalloys is the performance of process optimisation to maximise the mechanical properties. The energy density parameter has typically been used as a semi-quantitative approach to identify the energy threshold beyond which the material achieves virtually full consolidation. Nonetheless, some Ni-superalloys are susceptible to crack formation during SLM, which cannot be avoided via process optimisation. In this report, a comparative study is presented showing the utility of the energy density parameter in process optimisation for and / strengthened Ni-based superalloys. For both classes, it was found that the build density increases (i.e. void area (%) decreases) with the increase in the energy density. Nonetheless, no direct correlation can be found between the energy density parameter and the cracking density.