Materials

Example of an egg shaped form 3D printed in a flexible material using an SLA 3D printer. (Source: http://bit.ly/2k4hajb)

Understanding the different types of materials used across 3D printing technologies like FDM, SLA and SLS is a very important step in the design process. This is because choosing the correct material for a full three-dimensional (3D) object decides what it will look like once 3D printed, its properties (for example: hard versus flexible), and how it can be used in the real world.

Example of thermoplastic filaments used with FDM 3D Printing. (Source: http://bit.ly/2wXEctw)

FDM uses a part known as a filament to print out full 3D objects, layer by layer. A filament is a reel of material, usually a special type of plastic, called a thermoplastic. Thermoplastics are special because they can be softened using heat and can then instantly cool down to form very hard 3D objects, which can be tested on repeatedly- even at an industrial scale. Examples of different types of thermoplastics include; polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polystyrene (PS) and many others. Each of these thermoplastics is important to FDM technology because they let users print out full 3D objects for different uses. PLA is interesting because it is made from corn starch and can be composted. So it can degrade over time under the right conditions.

An SLA 3D Printer turning resin from liquid to solid. (Source: http://bit.ly/2ytU47W)

SLA technology uses a liquid plastic material called a photopolymer resin to print out full 3D objects, layer by layer. This photopolymer resin changes from a liquid state to a solid state when exposed to UV light. SLA photopolymer resins are also thermosetting plastics. This means that once 3D objects are finished, they are permanently set in their form and cannot be melted down and reshaped like thermoplastics. SLA photopolymers have limited color choices but can be used to create very smooth and detailed 3D prints. This makes SLA printers very popular in certain industries like engineering, dentistry and jewelry.

Wood is an option for SLS 3D printing. (Source: http://bit.ly/2wXZ6II)

SLS technology uses powdered forms of plastic, ceramic, glass and metal to print out full 3D objects, layer by layer. This technology uses a laser to turn these materials from powdered layers to solid layers, and is used to create complex 3D objects because supports are not needed. This makes SLS technology particularly exciting, which is why a lot of new types of powdered materials such as wood are being made.

The list of materials that is available for 3D Printing is rapidly evolving, and increasingly, materials are created to be sustainable and biodegradable too. Materials are an exciting area of 3D Printing, and each is driving exciting new development for the other: materials are being developed for 3D printing, expanding the range of applications and possibilities for 3D printing technologies; and as 3D printing grows, there is more interest in developing and exploring new or existing materials with different 3D printing technologies!

Stereolithography Apparatus (SLA)

The first steps of SLA printing. (Source: Cyant)

StereoLithography Apparatus (SLA) is an additive manufacturing process and an example of a 3D printing method. This technology uses an ultraviolet (UV) laser to turn light-sensitive resin (a liquid material that becomes hard when ultraviolet light is shined on it) into solid 3D objects, layer by layer.

Example of a tank for the resin from the Formlabs Form 2. (Source: http://bit.ly/2vWlDVN

SLA 3D printers need three main parts to do this; a tank filled with resin, a
platform that is lowered into this tank and the UV laser, which is controlled by a scanning system. In the first stage of SLA 3D printing, the platform is lowered into the resin by a small amount, where the UV laser then draws out a pattern. This pattern hardens instantly creating the first layer.

How the SLA Printing Process works. (Source: Cyant)

Next, the platform is further lowered into the resin by another small amount, where the UV laser draws a similar pattern that joins the first layer. This layering process happens again and again until a full 3D object is formed.

Final steps of SLA printing. (Source: Cyant)

Once fully formed, the 3D object, along with its ‘supports’, are removed from the tank and are washed in a solution (a special chemical liquid) to remove excess resin. After being washed, the 3D object is placed in a UV oven where it is further hardened.

SLA 3D printed flexible tire on ‘supports’. (Source:http://bit.ly/2wyIvN4)

Much like Fused Deposit Modeling (read more about FDM in the Lexicon), ‘supports’ are printed along with the 3D objects to make sure overhanging parts are supported against gravity while being printed. Once the full 3D object is completely hardened, the ‘supports’ are removed.

Selective Laser Sintering (SLS)

The SLS 3D printing process. (Source: Cyant)

Selective laser sintering (SLS) is another example of an Additive Manufacturing process and type of 3D printing method. This technology uses a laser to selectively join powdered plastic to build full three-dimensional (3D) objects, layer by layer.

S.L.S. 3D printers need three main parts to do this; a powder bed, a powder delivery system that rolls powdered plastic onto the bed and a laser that turns the powdered plastic into solid plastic layers.

An object printed with an SLS printer is pulled out of the powder bed. (Source: http://bit.ly/2x2Hpfw

Before SLS 3D printing starts, the machine heats up all the powdered plastic to soften it. This makes it easier and faster for the laser to turn the softened powdered plastic, into a liquid plastic that hardens instantly to make a solid plastic layer. In the first step of SLS 3D printing, the powder bed is lowered by a small amount and a layer of softened powdered plastic is rolled out onto it from the powder delivery system. The laser then draws a pattern on to the powder bed and the pattern hardens instantly, making the first layer.

How the SLS printing process works. (Source: Cyant)

Then, the powder bed is lowered again by the same amount as before, and a new layer of softened powdered plastic is rolled out onto it from the powder delivery system. The laser then draws another pattern on top of the first layer, creating a second layer. This new second layer hardens instantly and joins to the first layer. This layering process happens again and again until a full 3D object is created.

Example of a fully finished SLS 3D printed object. (Source: http://bit.ly/2vCVK20

Unlike in FDM and SLA (you can find out more about these in the Lexicon), 3D objects printed by an SLS 3D printer aren’t printed with ‘supports’. This is because the 3D object is always surrounded and supported by the powdered plastic. It is also important to know that in SLS 3D printing users cannot print out closed, empty 3D objects because a hole is needed to remove the powdered plastic once the object is finished. However, SLS creates smooth looking and polished objects.

Fused Deposition Modeling (FDM)

Felix 3D Printer using FDM technology. (Source: http://bit.ly/2veLng0)

Fused Deposition Modeling (FDM) is an additive manufacturing process and a type of 3D printing technology that builds a three-dimensional (3D) object, layer by layer, from the bottom up. This 3D printing method is a lot like chocolate piping to make or decorate chocolate pieces. During chocolate piping, chocolate is melted, inserted in a piping container such as a piping bag, and then pushed out through the piping nozzle. The pastry chef or chocolate maker follows a path to create a design. To build up the height of this design, another layer of chocolate is added along the same path. This layering process is repeated until a 3D chocolate decoration is made.

Chocolate piping at the Godiva Factory. (Source: http://bit.ly/2fWBykA)

With the FDM method, the bag of chocolate is replaced by a reel of material called a filament, which is then heated in the FDM nozzle. This softens the filament. The nozzle then runs the softened filament along a path to build a design by layers that are around the same thickness of a human hair. This layering process is repeated until a full 3D object is made.

How the FDM printing process works. (Source: Cyant)

Some 3D printed models come with ‘supports’. These are thin, break-away pieces of plastic that support 3D printed models with overhanging parts.

Overview of the FDM Printing with supports. (Source: Cyant)

These might cause the model to sag, so ‘supports’ are printed beneath the overhanging parts and hold up the model while it’s printed. Once ‘supports’ are removed, the 3D object is then ready.

3D printed rabbit with ‘supports’ intact. (Source: http://bit.ly/2x42bbs)

FDM is currently the most popular 3D printing method, as the technology is easy-to- use, office and home friendly and clean!

3D Printing

The Additive Manufacturing process - Building an object layer by layer. (Source: Cyant)

Additive Manufacturing is the process of creating a three-dimensional (3D) object by adding one layer of material on to another layer until a full object is created. The main difference between additive and traditional manufacturing methods is based on how objects are made. During traditional manufacturing, materials are often molded, removed or carved out, but during additive manufacturing, materials are only ever added.

Most 3D printers are a form of additive manufacturing, but some use different additive methods to create 3D objects. Examples of different 3D printing processes include; Fuse Deposition Modeling (FDM), Selective Laser Sintering (SLS) and Stereolithographic Apparatus (SLA).

From 3D modeling to 3D printing - Part 1/2. (Source: Cyant)

Despite being different 3D printing processes, they all follow a similar set of steps to create 3D printed objects. First, a 3D modeling program (such as Cyant’s Lab) is used to create a 3D computer model. The computer model is then saved in a file that describes the geometry of the model. A typical format for this file is the STL file format.

From 3D modeling to 3D printing Part 2/2. (Source: Cyant)

The model file is then opened in a slicer software, where the model is “sliced” into the individual layers that will be printed. The slicer software also collects information from the model file and creates a G-code. This code instructs the 3D printer on how to print the 3D object- one layer at a time- by controlling the speed, movement, height and path of the 3D printing machine. Together these processes bring your 3D models to life!

A complex 3D printed object. (Source: Brewbooks from near Seattle, USA)

3D Printing enables the creation of parts and objects that cannot be produced with traditional methods. This means new things can now be designed and this makes this technology very exciting. Still, 3D Printing can also be used with traditional crafts. So beautifully designed objects can be created from the combination of time-proven techniques and new technologies!