What is 3D Printing?

3D printing or additive manufacturing (AM) technologies create three-dimensional parts from computer-aided design (CAD) models by successively adding material layer by layer until physical part is created.

While 3D printing technologies have been around since the 1980s, recent advances in machinery, materials, and software have made 3D printing accessible to a wider range of businesses, enabling more and more companies to use tools previously limited to a few high-tech industries.

Today, professional, low-cost desktop and benchtop 3D printers accelerate innovation and support businesses in various industries including engineering, manufacturing, dentistry, healthcare, education, entertainment, jewelry, and audiology.

How Does 3D Printing Work?

All 3D printing processes start with a CAD model that is sent to software to prepare the design. Depending on the technology, the 3D printer might produce the part layer by layer by solidifying resin or sintering powder. The parts are then removed from the printer and post-processed for the specific application.

1. Design

3D printers create parts from three-dimensional models, the mathematical representations of any three-dimensional surface created using computer-aided design (CAD) software or developed from 3D scan data. The design is then exported as an STL or OBJ file readable by print preparation software.

3D printers include software to specify print settings and slice the digital model into layers that represent horizontal cross-sections of the part. Adjustable printing settings include orientation, support structures (if needed), layer height, and material. Once setup is complete, the software sends the instructions to the printer via a wireless or cable connection.

2. 3D Print

Some 3D printers use a laser to cure liquid resin into hardened plastic, others fuse small particles of polymer powder at high temperatures to build parts. Most 3D printers can run unattended until the print is complete, and modern systems automatically refill the material required for the parts from cartridges.

With Formlabs 3D printers, an online Dashboard allows you to remotely manage printers, materials, and teams.

3. Post-Process

Depending on the technology and the material, the printed parts may require rinsing in isopropyl alcohol (IPA) to remove any uncured resin from their surface, post-curing to stabilize mechanical properties, manual work to remove support structures, or cleaning with compressed air or a media blaster to remove excess powder. Some of these processes can be automated with accessories.

3D printed parts can be used directly or post-processed for specific applications and the required finish by machining, priming, painting, fastening or joining. Often, 3D printing also serves as an intermediate step alongside conventional manufacturing methods, such as positives for investment casting jewelry and dental appliances, or molds for custom parts.

Types of 3D Printers

The three most established types of 3D printers for plastics parts are stereolithography (SLA), selective laser sintering (SLS), and fused deposition modeling (FDM). Formlabs offers two professional 3D printing technologies, SLA and SLS, bringing these powerful and accessible industrial fabrication tools into the creative hands of professionals around the world.

Stereolithography (SLA)

Stereolithography was the world’s first 3D printing technology, invented in the 1980s, and is still one of the most popular technologies for professionals. SLA 3D printers use a laser to cure liquid resin into hardened plastic in a process called photopolymerization.

SLA resin 3D printers have become vastly popular for their ability to produce high-accuracy, isotropic, and watertight prototypes and parts in a range of advanced materials with fine features and smooth surface finish. SLA resin formulations offer a wide range of optical, mechanical, and thermal properties to match those of standard, engineering, and industrial thermoplastics.

Resin 3D printing a great option for highly detailed prototypes requiring tight tolerances and smooth surfaces, such as molds, patterns, and functional parts. SLA 3D printers are widely used in a range of industries from engineering and product design to manufacturing, dentistry, jewelry, model making, and education.

Stereolithography is ideal for:

· Rapid prototyping

· Functional prototyping

· Concept modeling

· Short-run production

· Dental applications

· Jewelry prototyping and casting

Stereolithography (SLA) 3D printing uses a laser to cure liquid photopolymer resin into solid isotropic parts.

SLA parts have sharp edges, a smooth surface finish, and minimal visible layer lines.

Selective Laser Sintering (SLS)

Selective laser sintering (SLS) 3D printers use a high-power laser to sinter small particles of polymer powder into a solid structure. The unfused powder supports the part during printing and eliminates the need for dedicated support structures. This makes SLS ideal for complex geometries, including interior features, undercuts, thin walls, and negative features. Parts produced with SLS printing have excellent mechanical characteristics, with strength resembling that of injection-molded parts.

The most common material for selective laser sintering is nylon, a popular engineering thermoplastic with excellent mechanical properties. Nylon is lightweight, strong, and flexible, as well as stable against impact, chemicals, heat, UV light, water, and dirt.

The combination of low cost per part, high productivity, and established materials make SLS a popular choice among engineers for functional prototyping, and a cost-effective alternative to injection molding for limited-run or bridge manufacturing.

Selective laser sintering is ideal for:

· Functional prototyping

· End-use parts

· Short-run, bridge, or custom manufacturing

SLS 3D printers use a high-powered laser to fuse small particles of polymer powder. 

SLS parts have a slightly rough surface finish, but almost no visible layer lines.

Fused Deposition Modeling (FDM)

Fused deposition modeling (FDM), also known as fused filament fabrication (FFF), is the most widely used type of 3D printing at the consumer level. FDM 3D printers work by extruding thermoplastic filaments, such as ABS (Acrylonitrile Butadiene Styrene), PLA (Polylactic Acid), through a heated nozzle, melting the material and applying the plastic layer by layer to a build platform. Each layer is laid down one at a time until the part is complete.

FDM 3D printers are well-suited for basic proof-of-concept models, as well as quick and low-cost prototyping of simple parts, such as parts that might typically be machined. However, FDM has the lowest resolution and accuracy when compared to SLA or SLS and is not the best option for printing complex designs or parts with intricate features. Higher-quality finishes may be obtained through chemical and mechanical polishing processes. Industrial FDM 3D printers use soluble supports to mitigate some of these issues and offer a wider range of engineering thermoplastics, but they also come at a steep price.

Fused deposition modeling is ideal for:

· Basic proof-of-concept models

· Simple prototyping

FDM 3D printers build parts by melting and extruding thermoplastic filament, which a printer nozzle deposits layer by layer in the build area.

FDM parts tend to have visible layer lines and might show inaccuracies around complex features.