DMLS is a process whereby a laser is used to sinter a powdered material (usually metal) together to create a 3D structure or part. It is similar to SLS (selective laser sintering), but has different technical details.
The process begins with a STL file, as per other additive manufacturing processes, and an operator orients the part and adds any required support structures. The file, along with its support structure, is then sliced into layers and is sent to the DMLS machine. These layer slices are equal to the thickness that the machine will build each layer at. The powdered material is dispensed on the build platform, and a high power laser fuses the metal powder into a solid part. The build platform then lowers by the thickness of one layer, more powder is dispensed, and the process repeats until the part is complete.
DMLS allows very complex geometries, that would normally be thought impossible, to be built very quickly. It does not require any special tooling to be manufactured before hand, and internal geometries such as passageways and channels can be built inside the parts. This makes the process ideal for prototyping, but also for short production runs of final components. It has the added benefit that provided the build envelope is large enough; multiple parts can be built at once. DMLS is used across aerospace, motorsport, automotive, dental & medical industries, as it gives the ability to manufacture highly complex, small to medium parts very quickly.
DMLS does have some limitations – the build envelopes on current machines are still relatively small, so large DMLS parts cannot be manufactured in one piece, and feature details and surface finish are not quite up there with CNC milled or turned parts – to achieve a mirror or extremely smooth finish, the surfaces will have to be polished. Also, the support removal method is much more involved than in SLA & FDM, as the support structures have to be removed by way of machining, EDM and/or grinding – a very time consuming process that requires a high level of accuracy. The surface finish of completed parts is comparable to cast parts, whilst the mechanical properties are comparable to that of cast or machined parts.
Materials currently in use in DMLS include Aluminium, Stainless steel, Maraging steel, Cobalt Chrome, Inconel & titanium.