3D Printing Process Introduction
SLA
Stereolithography (SLA) is an additive manufacturing process that works in a different way to FDM. In SLA 3D printing, a 3D object is created with a laser, which is directed at areas of photosensitive liquid resin. The laser causes areas of the resin to harden, forming a solid part.
The SLA process uses a moving platform in a tank of liquid resin. The platform moves up or down after each layer is fully cured, which is different to FDM, in which the platform remains stationary. The SLA laser is focused using a system of mirrors.
SLA can only be used with photosensitive polymers, but offers high accuracy and fine details. It also predates other forms of additive manufacturing, having been invented back in the 1980s.
SLS
Selective Laser Sintering (SLS) is a powder bed additive manufacturing process used to make parts from thermoplastic polymer powders. It is commonly used for functional parts, since SLS printed components have good mechanical properties.
An SLS 3D printer works by sintering areas of powder with a laser. During the process, a thin layer of powder is distributed evenly across the build platform, after which the laser sinters selected areas of the 2D layer.
When the layer is complete, the platform is lowered, more powder added, and the laser sinters the next layer.
When all layers are complete, the part is left to cool. Unused powder is kept to be used again, and the part is cleaned to remove excess material.
SLM
Selective Laser Melting (SLM) is a metal additive manufacturing process used to create functional, end-use products. SLM printers use a laser to melt particles of metal powder, fusing them together to form a 3D object.
An SLM 3D printer uses a gas-filled chamber containing the metal powder. The laser passes over the desired sections of the powder, causing the particles to melt and bond. When a layer is complete, the build platform moves down to allow the laser to pass over the next layer.
The SLM process can be used to create strong metal parts with highly complex shapes, providing engineers with new levels of design freedom.
FDM
Fused Deposition Modeling (FDM) is the most widely used additive manufacturing process for desktop 3D printers. The process involves extruding a melted plastic from a computer-controlled nozzle, building a part layer by layer.
FDM 3D printers use a spool of filament as raw material. This filament is directed into the print head, where it is melted and deposited onto the incomplete part. In accordance with computer instructions, the print head moves along 3 axes in order to deposit material in the right place.
Because the material cools after it is deposited, further layers of material can be deposited on top of the existing layers, allowing for the creation of 3D shapes.
