What is 3D Printing?

3D printing or additive manufacturing is a process of making three dimensional solid objects from a digital file.

The creation of a 3D printed object is achieved using additive processes. In an additive process an object is created by laying down successive layers of material until the object is created. Each of these layers can be seen as a thinly sliced horizontal cross-section of the eventual object.

3D printing is the opposite of subtractive manufacturing which is cutting out / hollowing out a piece of metal or plastic with for instance a milling machine.

3D printing enables you to produce complex (functional) shapes using less material than traditional manufacturing methods.

How Does 3D Printing Work?

It all starts with the creation of a 3D model in your computer. This digital design is for instance a CAD (Computer Aided Design) file. A 3D model is either created from the ground up with 3D modeling software or based on data generated with a 3D scanner. With a 3D scanner you’re able to create a digital copy of an object.

3D Scanners

Currently, prices of 3D scanners range from expensive industrial grade 3D scanners to $30 DIY scanners anyone can make at home. We’ve created a handy guide to scanning technology right here, rating them by price, speed, precision and software capabilities.

3D Modeling Software

3D modeling software come in many forms. There’s industrial grade software that costs thousands a year per license, but also free open source software, like Blender, for instance. You can find some beginner video tutorials on our Blender tutorials page.

3D modeling software are often made to suit the functions of the user’s industry. This has resulted in the rise of software suited to specific niches. As a result, there are software applications on the market that cater to aerospace or transportation, furniture design or fabrics and fashion among many others.

For this reason, when you are starting out, the amount of choices can be a bit overwhelming, we recommend starting with Tinkercad. Tinkercad is available for free and it works in browsers that support WebGL, for instance Google Chrome. They offer beginner lessons and has a built in option to get your object printed via a 3D print service.

Now that you you have a 3D model, the next step is to prepare it in order to make it 3D printable.

Slicing: From 3D Model to 3D Printer

You will have to slice a 3D model in order to make it 3D printable. Slicing is dividing a 3D model into hundreds or thousands of horizontal layers and is done with slicing software.

Sometimes it’s possible to slice a 3D file within a 3D modeling software or in the 3D printer itself. It is also possible that you are forced to use a certain slicing tool for a certain 3D printer.

When your 3D model is sliced, you are ready to feed it to your 3D printer. This can be done via USB, SD or Wi-Fi. It really depends on what 3D printer brand you work with. When a file is uploaded in a 3D printer, the object is ready to be 3D printed layer by layer.

Learn How to 3D Print – Where to Start?

Getting started with 3D printing means asking yourself what you would like to learn first. Are you interested in the hardware, or do you want to focus on the end result – creating objects? Answering this question could lead you to the decision if whether you should buy a pre-assembled 3D Printer or a DIY 3D Printer kit. Read more in our 3D Printers for Beginners buyers guide.

Which 3D Printer Is Right for You?
Want to buy a 3D printer but you have a tight budget? Starting your journey into 3D printing doesn’t need to be expensive. There are plenty cheap 3D printers under $250.

Besides the examples above, there are a bunch of different elements which will help decide what the best 3D printer is for you. Will it be used in the classroom? Will it be used for small batch production? For more information, please read our buyers guide: the best 3D printers of 2019.

Types of 3D Printing Technologies and Processes

There are several ways to 3D print. All these technologies are additive, differing mainly in the way layers are build to create an object.

Some methods use melting or softening material to extrude layers. Others cure a photo-reactive resin with a UV laser (or another similar light source) layer by layer.

To be more precise: since 2010, the American Society for Testing and Materials (ASTM) group “ASTM F42 – Additive Manufacturing”, developed a set of standards that classify the Additive Manufacturing processes into 7 categories  according to Standard Terminology for Additive Manufacturing Technologies. These seven processes are:

Vat Photopolymerisation

A 3D printer based on the Vat Photopolymerisation method has a container filled with photopolymer resin which is then hardened with a UV light source.

Stereolithography (SLA)

The most commonly used technology in this processes is Stereolithography (SLA). This technology employs a vat of liquid ultraviolet curable photopolymer resin and an ultraviolet laser to build the object’s layers one at a time. For each layer, the laser beam traces a cross-section of the part pattern on the surface of the liquid resin. Exposure to the ultraviolet laser light cures and solidifies the pattern traced on the resin and joins it to the layer below.

After the pattern has been traced, the SLA’s elevator platform descends by a distance equal to the thickness of a single layer, typically 0.05 mm to 0.15 mm (0.002″ to 0.006″). Then, a resin-filled blade sweeps across the cross section of the part, re-coating it with fresh material. On this new liquid surface, the subsequent layer pattern is traced, joining the previous layer. The complete three dimensional object is formed by this project. Stereolithography requires the use of supporting structures which serve to attach the part to the elevator platform and to hold the object because it floats in the basin filled with liquid resin. These are removed manually after the object is finished.

This technique was invented in 1986 by Charles Hull, who also at the time founded the company, 3D Systems.

Digital Light Processing (DLP)

DLP or Digital Light Processing refers to a method of printing that makes use of light and photosensitive polymers. While it is very similar to stereolithography, the key difference is the light-source. DLP utilises traditional light-sources like arc lamps.

In most forms of DLP, each layer of the desired structure is projected onto a vat of liquid resin that is then solidified layer by layer as the buildplate moves up or down. As the process does each layer successively, it is quicker than most forms of 3D printing.

The Envision Tec Ultra, MiiCraft High Resolution 3D printer, and Lunavast XG2 are examples of DLP printers.

Continuous Liquid Interface Production (CLIP)

The newest and fastest process using Vat Photopolymerisation is called CLIP, short for Continuous Liquid Interface Production, invented by a company called Carbon.

Digital Light Synthesis

The heart of the CLIP process is Digital Light Synthesis technology. In this technology, light from a custom high performance LED light engine projects a sequence of UV images exposing a cross section of the 3D printed part causing the UV curable resin to partially cure in a precisely controlled way. Oxygen passen through the oxygen permeable window creating a thin liquid interface of uncured resin between the window and the printed part known as the dead zone. The dead zone is as thin as ten of microns. Inside the dead zone, oxygen prohibits light from curing the resin situated closest to the window therefore allowing the continuous flow of liquid beneath the printed part. Just above the dead zone the UV projected light upwards causes a cascade like curing of the part.

Simply printing with Carbon’s hardware alone does not allow for end use properties with real world applications. Once the light has shaped the part, a second programmable curing process achieves the desired mechanical properties by baking the 3d printed part in a thermal bath or oven. Programmed thermal curing sets the mechanical properties by triggering a secondary chemical reaction causing the material to strengthen achieving the desired final properties.

Parts printed with Digital Light Synthesis™ are much more like injection-molded parts. Digital Light Synthesis™ produces consistent and predictable mechanical properties, creating parts that are solid on the inside

Material Jetting

In this process, material is applied in droplets through a small diameter nozzle, similar to the way a common inkjet paper printer works, but it is applied layer-by-layer to a build platform making a 3D object and then hardened by UV light.

Binder Jetting

With binder jetting two materials are used: powder base material and a liquid binder. In the build chamber, powder is spread in equal layers and binder is applied through jet nozzles that “glue” the powder particles in the shape of a programmed 3D object. The finished object is “glued together” by binder remains in the container with the powder base material. After the print is finished, the remaining powder is cleaned off and used for 3D printing the next object. This technology was first developed at the Massachusetts Institute of Technology in 1993 and in 1995 Z Corporation obtained an exclusive license.

Material Extrusion

The most commonly used technology in this process is Fused Deposition Modeling (FDM).

Fused Deposition Modeling (FDM)

Fused deposition modelling (FDM), a method of rapid prototyping: 1 – nozzle ejecting molten material (plastic), 2 – deposited material (modelled part), 3 – controlled movable table. Image source: Wikipedia, made by user Zureks under CC Attribution-Share Alike 4.0 International license.

The FDM technology works using a plastic filament or metal wire which is unwound from a coil and supplying material to an extrusion nozzle which can turn the flow on and off. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package. The object is produced by extruding melted material to form layers as the material hardens immediately after extrusion from the nozzle. This technology is most widely used with two plastic 3D printer filament types: ABS (Acrylonitrile Butadiene Styrene) and PLA (Polylactic acid). Though many other materials are available ranging in properties from wood fill to flexible and even conductive materials.

FDM was invented by Scott Crump in the late 80’s. After patenting this technology he started the company Stratasys in 1988. The term Fused Deposition Modeling and its abbreviation to FDM are trademarked by Stratasys Inc.

Fused Filament Fabrication (FFF)

The exactly equivalent term, Fused Filament Fabrication (FFF), was coined by the members of the RepRap project to give a phrase that would be legally unconstrained in its use.

There are many different FFF 3D Printer configurations. The most popular arrangements are:

  • Cartesian-XY-Head
  • Cartesian-XZ-Head
  • Delta
  • Core XY

Looking for an overview of all FFF 3D printers? Use our tool and compare 3D printer price.

Powder Bed Fusion

The most commonly used technology in this processes is Selective Laser Sintering (SLS).

Selective Laser Sintering (SLS)

SLS uses a high power laser to fuse small particles of plastic, ceramic or glass powders into a mass that has the desired three dimensional shape. The laser selectively fuses the powdered material by scanning the cross-sections (or layers) generated by the 3D modeling program on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness. Then a new layer of material is applied on top and the process is repeated until the object is completed.

SLS system schematic. Image source: Wikipedia from user Materialgeeza under Creative Commons Attribution-Share Alike 3.0 Unported license

Direct Metal Laser Sintering (DMLS)

DMLS is basically the same as SLS, but uses metal instead of plastic, ceramic or glass.

All untouched powder remains as it is and becomes a support structure for the object. Therefore there is no need for any support structure which is an advantage over SLS and SLA. All unused powder can be used for the next print. SLS was developed and patented by Dr. Carl Deckard at the University of Texas in the mid-1980s, under sponsorship of DARPA.

Sheet Lamination

Sheet lamination involves material in sheets which is bound together with external force. Sheets can be metal, paper or a form of polymer. Metal sheets are welded together by ultrasonic welding in layers and then CNC milled into a proper shape. Paper sheets can be used also, but they are glued by adhesive glue and cut in shape by precise blades. A leading company in this field is Mcor Technologies.

Directed Energy Deposition

This process is mostly used in the high-tech metal industry and in rapid manufacturing applications. The 3D printing apparatus is usually attached to a multi-axis robotic arm and consists of a nozzle that deposits metal powder or wire on a surface and an energy source (laser, electron beam or plasma arc) that melts it, forming a solid object.