Types Of 3D Printing Part 2

3D Printing is creating a whole new world of manufacturing, with the ability to create complex designs with quality and precision and deliver faster, more affordable results. In this article, let’s continue to learn other basic types of 3D printing technology.

Digital Light Processing (DLP)

Larry Hornbeck of Texas Instruments invented the technology for Digital Light Processing in 1987. And this technology became popular for its use in the production of projectors.

Once the 3D model created in the 3D modeling software is sent to the printer, a vat of liquid polymer is exposed to light from a DLP projector under safelight conditions. The DLP projector displays the image of the 3D model onto the liquid polymer. The exposed liquid polymer hardens and the build plate moves down and the liquid polymer is once more exposed to light. The process is repeated until the 3D model is complete and the vat is drained of liquid, revealing the solidified model. DLP 3D printing is faster and can print objects with a higher resolution.

DLP is very similar to SLA with one significant difference -- where SLA machines use a laser that traces a layer, a DLP machine uses a digital light projector to flash a single image of each layer all at once (or multiple flashes for larger parts). Meanwhile, DLP has quicker print times than SLA in light of the fact that each layer is uncovered at the same time, rather than following the cross-part of a zone with the purpose of a laser.

DLP printing can be used to print extremely intricate resin design items like toys, jewelry molds, dental molds, figurines and other items with fine details.

Selective Laser Melting (SLM)

Selective laser melting (SLM), also called direct metal laser melting (DMLM), is one of the new additive manufacturing techniques that is utilized both for rapid prototyping and mass production. 

During the SLM process, a product is formed by selectively melting successive layers of powder by the interaction of a laser beam. Upon irradiation, the powder material is heated and, if sufficient power is applied, melts and forms a liquid pool. Afterwards, the molten pool solidifies and cools down quickly, and the consolidated material starts to form the product. After the cross-section of a layer is scanned, the building platform is lowered by an amount equal to the layer thickness and a new layer of powder is deposited. This process is repeated until the product is completed.

SLM has its own pros and cons.

SLM has the ability to realize complex shapes or internal features (which would be incredibly difficult or expensive to achieve via traditional manufacturing). And powder during this process is melted only locally by the laser and the rest of the powder can be recycled for further fabrication.

However, the cost for SLM is expensive, especially if parts aren’t optimized or designed for the process. Besides, SLM is currently limited to relatively small parts, and specialized design, manufacturing skills and knowledge are needed.

Electron Beam Melting (EBM)

In 1993, Arcam collaborated with Chalmers University of Technology in Gothenburg in filing an application for a patent on the principles of EBM. In 1997, Arcam AB was founded and the company has continued to develop EBM and commercialize EBM printing.

A powdered metal is melted by a high-energy beam of electrons in EBM. A focused electron beam scans across a thin layer of powder, causing localized melting and solidification over a specific cross-sectional area. These areas are built up to create a solid object. Production takes place in a vacuum chamber to guard against oxidation that can compromise highly reactive materials.

EBM builds high-strength parts that make the most of the native properties of the metals used in the process, eliminating impurities that may accumulate when using casting metals or using other methods of fabrication. It is used to print components for aerospace, automotive, defense, petrochemical, and medical applications.

Multi Jet Fusion (MJF)

Developed by HP, Multi Jet Fusion (MJF) 3D printing is used as a manufacturing strategy to create unique parts with exquisite surface finishing in a short amount of time.

Multi Jet Fusion uses an inkjet array to selectively apply fusing and detailing agents across a bed of nylon powder, which are then fused by heating elements into a solid layer. After each layer, powder is distributed on top of the bed and the process repeats until the part is complete. When the build finishes, the entire powder bed with the encapsulated parts is moved to a processing station where a majority of the loose powder is removed by an integrated vacuum. Parts are then bead blasted to remove any of the remaining residual powder before ultimately reaching the finishing department where they are dyed black to improve cosmetic appearance.