ABSTRACT
Additive manufacturing has the capability to build three-dimensional objects directly from a computer design by selectively depositing material. It allows the construction of parts with complete internal or external geometries. However, most conventional metal additive manufacturing technologies are limited in their ability to build overhanging structures. Kruth et al.1 and Thomas and Bibb2 found that selective laser melting (SLM) was limited in its ability to build overhanging structures with an angle less than 40° to 45° from the horizontal without building xed support structures. Fixed support structures provide a means to support tracks and features during solidication and are usually removed during post-processing of parts. If the individual tracks are supported during solidication it may be possible to create overhanging tracks or tracks that start on a substrate but stretch into free space, as shown in Figure 2.1. Overhanging features can be built by layering individual overhanging tracks. After solidication it may not be necessary to continue supporting the track which would allow deposition in any plane or straight into free space.
