Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS)
Powder bed fusion (PBF) is an AM process where powder bed is fused by thermal energy to create the cross-sections of a part. Basically, in the PBF process, the build platform is covered with powder and the thermal energy is hit on to the cross-section of the layer inducing fusion between powder particles. The build platform is lowered for the next layer and the process repeats until the part is built.
The SLM and DMLS are one of the printing technique of Powder bed fusion Technology. The part built in SLM/DMLS is similar to SLS, but these techniques are used to 3d print metals instead of polymers. The DMLS process heats the metal powder to a temperature such that it fuses on the molecular level. The SLM process uses the laser source to fully melt the metal powder, thus forming a homogeneous part. Thus, the SLM technology can produce only from single element materials. Whereas, the DMLS process can be used to 3d print parts using metal alloys. The temperature required to fuse the metal powder is very high and this generates residual stresses in the part while printing. Thus, the parts generated using SLM/DMLS require support material to minimize distortion in the part. After the part is successfully printed, the supports should be removed manually or by CNC machining, and then are thermally treated to remove the residual stresses. The common applications of the DMLS/SLM technologies are as follows: Functional metal parts used in aerospace and automotive sectors, medical parts (with low volume, high complexity), dental applications such as crowns, bridges etc.
Advantages of SLM/DMLS
• Strongest functional parts.
• Can produce complex geometries that traditional machines cannot produce.
• Ideal for high-end engineering applications
Disadvantages of SLM/DMLS
• Very high cost.
• Limited build volume
• High power usage