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Types of 3D Printing Processes

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3D printers build parts layer by layer and each printer differs in how they form plastic and metal parts, as well as in material selection, surface finish, and manufacturing speed and cost. There are many types of 3D printing processes, some of which are listed and explained below. Read more to see which process is best for different purposes.

Types of 3D Printing Processes

  • Vat Photopolymerization (SLA, DLP, CDLP)

  • Material Extrusion (FDM)

  • Powder Bed Fusion (SLS, SLM/DMLS, EBM, Multi Jet Fusion)

  • Binder Jetting

Vat Photopolymerization (SLA, DLP, CDLP)

The first of the technologies to be introduced to the market and still regarded as one of the industry standards for both its accuracy and material capabilities is Vat Photopolymerization.

The two most common types are Stereolithography (SLA) and Digital Light Processing (DLP). Both use liquid resins as a build material which are placed into a build tank, usually with a clear windowed bottom.

A build platform is then submerged and a light source is introduced, tracing specific patterns, solidifying a single layer at a time, mapped to the design of the final object. For each consecutive layer, the build platform will raise by a small increment, allowing additional resin to be introduced and solidified. This process is repeated until the final object is complete.

SLA & DLP printers are ideal for printing objects that require a high level of detail and an aesthetic surface finish. This makes them ideal for use in creating intricate medical devices such as hearing aids as well as creating highly detailed anatomical models for pre-operative planning.

Vendors include 3D Systems, Formlabs, Envisiontec and Carbon.

Material Extrusion (FDM)

Fused Deposition Modeling (FDM) was the first mainstream desktop technology introduced to the market and as a result, is one of the most widely used technologies.

The technology uses a solid spool of plastic material (typically PLA or ABS) which is uncoiled during the printing process into a heated printer nozzle to make it molten.

The nozzle continually extrudes molten plastic onto a flat build platform following a predefined path on its XY axis to effectively draw one layer of material at a time matching the CAD model uploaded to the printer.

Due to the relatively low cost of the technology and materials, it has opened the technology up to be used in a wide variety of applications.

Within the medical field, FDM is a good choice when making larger, less complex geometries such as prosthetic fairings & lightweight splints.

Vendors include: Stratasys, Ultimaker, Makerbot and Markforged.

Powder Bed Fusion (SLS, SLM/DMLS, EBM, Multi Jet Fusion)

The process of powder bed fusion is most common in prototyping engineering fields such as automotive or aeronautical. This is due to the superior mechanical properties of the parts which come straight from the printer, which can be used for functional simulation testing.

The process of Selective Laser Sintering (SLS) works by heating a bed of powdered material (typically Nylon or PEEK materials) to just below its melting point.

A laser is then drawn over the surface of the material in a cross-section, matching that of the 3D model uploaded to the system. This laser ‘sinters’ a fine layer of powder while leaving all other material around it still in powder form.

After each layer is sintered, the bed lowers and a roller passes across the top of the bed to deposit a fine layer of additional powder before the sintering process is repeated until a finished part emerges.

One of the technology’s main benefits, aside from its superior mechanical properties, is that supports are not required when using the technology. This is because unsintered powder within the bed doubles as support material during the print process which can be easily removed and recycled for additional prints.

SLS is mainly used within the industrial engineering space because of the relative size, power requirements and cost of equipment. However, much lower cost and office friendly versions of the technology have been emerging, allowing the technology to be integrated into many other applications.

SLS is a great choice when considering applications where mechanical properties of parts are paramount. This makes it ideal for use in medicine when parts are being subject to daily mechanical strain such as lightweight cast design & scoliosis braces and prosthetic applications.

Vendors include: EOS, 3D Systems, Formlabs and Renishaw.

Binder Jetting

Binder jetting is the process of dispensing a binding agent onto a powder bed to build a part, one layer at a time. These layers bind to one another to form a solid component. Solid parts are created from a bed of powdered material by binding them together with an adhesive or reagent.

Binder jetting is like SLS technologies as it comprises a bed of powdered material. However instead of a laser sintering each layer, particles are bound together using material that is sprayed over the top of the print bed.

Once the binder is deposited, matching a cross section of the CAD file, a new layer of material is deposited on with a roller system and the process is repeated until there is a fully formed part.

The most common material for this technology is gypsum powder. However, larger industrial machines can also manufacture parts in glass or metal powders using the same technique. When using the common gypsum powder, the binding agent can be integrated within a conventional inkjet printer head to deposit colored material to make fully colored finished parts.

Binder jet printing is great for full-color display parts where mechanical functionality and material properties are not required.

This makes it ideal for applications in colored prototype modeling or in anatomical models when a number of detailed anatomical structures have to be delineated from one another,  such as cardiac modeling.

Vendors include: 3D Systems, Voxeljet and ExOne.

Patient-Specific Medical 3D Models by Axial3D

At Axial3D, we segment 2D patient scans and convert them into 3D visuals and printable files in our Segmentation-as-a-Service software. We can then print the models in our print lab, or through our partners. The print-ready files can also be output into a hospital’s print lab. To see first hand how our 3D solutions can help your organization, consult our experts for a trial.

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