3D printer concept

What is 3D Printing? - Technology Definition and Types

3D printing, also known as additive manufacturing, is a method of creating a three dimensional object layer-by-layer using a computer created design.

3D printing is an additive process whereby layers of material are built up to create a 3D part. This is the opposite of subtractive manufacturing processes, where a final design is cut from a larger block of material. As a result, 3D printing creates less material wastage.

This article is one of a series of TWI frequently asked questions (FAQs).

3D printing is also perfectly suited to the creation of complex, bespoke items, making it ideal for rapid prototyping.

What materials can be used?
History
Technologies
Process types
How long does it take?
Advantages and disadvantages
What is an STL file?
Industries
Services
FAQs

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There are a variety of 3D printing materials, including thermoplastics such as acrylonitrile butadiene styrene (ABS), metals (including powders), resins and ceramics.

Who Invented 3D Printing?

The earliest 3D printing manufacturing equipment was developed by Hideo Kodama of the Nagoya Municipal Industrial Research Institute, when he invented two additive methods for fabricating 3D models.

When was 3D Printing Invented?

Building on Ralf Baker's work in the 1920s for making decorative articles (patent US423647A), Hideo Kodama's early work in laser cured resin rapid prototyping was completed in 1981. His invention was expanded upon over the next three decades, with the introduction of stereolithography in 1984. Chuck Hull of 3D Systems invented the first 3D printer in 1987, which used the stereolithography process. This was followed by developments such as selective laser sintering and selective laser melting, among others. Other expensive 3D printing systems were developed in the 1990s-2000s, although the cost of these dropped dramatically when the patents expired in 2009, opening up the technology for more users.

There are three broad types of 3D printing technology; sintering, melting, and stereolithography.

Sintering is a technology where the material is heated, but not to the point of melting, to create high resolution items. Metal powder is used for direct metal laser sintering while thermoplastic powders are used for selective laser sintering.
Melting methods of 3D printing include powder bed fusion, electron beam melting and direct energy deposition, these use lasers, electric arcs or electron beams to print objects by melting the materials together at high temperatures.
Stereolithography utilises photopolymerization to create parts. This technology uses the correct light source to interact with the material in a selective manner to cure and solidify a cross section of the object in thin layers.

Types of 3D printing

3D printing, also known as additive manufacturing, processes have been categorised into seven groups by ISO/ASTM 52900 additive manufacturing - general principles - terminology. All forms of 3D printing fall into one of the following types:

Binder Jetting
Direct Energy Deposition
Material Extrusion
Material Jetting
Powder Bed Fusion
Sheet Lamination
VAT Polymerization

Binder Jetting

Binder jetting deposits a thin layer of powered material, for example metal, polymer sand or ceramic, onto the build platform, after which drops of adhesive are deposited by a print head to bind the particles together. This builds the part layer by layer and once this is complete post processing may be necessary to finish the build. As examples of post processing, metal parts may be thermally sintered or infiltrated with a low melting point metal such as bronze, while full-colour polymer or ceramic parts may be saturated with cyanoacrylate adhesive.

Binder jetting can be used for a variety of applications including 3D metal printing, full colour prototypes and large scale ceramic moulds.

Direct Energy Deposition

Direct energy depositioning uses focussed thermal energy such as an electric arc, laser or electron beam to fuse wire or powder feedstock as it is deposited. The process is traversed horizontally to build a layer, and layers are stacked vertically to create a part.

This process can be used with a variety of materials, including metals, ceramics and polymers.

Material Extrusion

Material extrusion or fused deposition modelling (FDM) uses a spool of filament which is fed to an extrusion head with a heated nozzle. The extrusion head heats, softens and lays down the heated material at set locations, where it cools to create a layer of material, the build platform then moves down ready for the next layer.

This process is cost-effective and has short lead times but also has a low dimensional accuracy and often requires post processing to create a smooth finish. This process also tends to create anisotropic parts, meaning that they are weaker in one direction and therefore unsuitable for critical applications.

Material Jetting

Material jetting works in a similar manner to inkjet printing except, rather than laying down ink on a page, this process deposits layers of liquid material from one or more print heads. The layers are then cured before the process begins again for the next layer. Material jetting requires the use of support structures but these can be made from a water-soluble material that can be washed away once the build is complete.

A precise process, material jetting is one of the most expensive 3D printing methods, and the parts tend to be brittle and will degrade over time. However, this process allows for the creation of full-colour parts in a variety of materials.

Powder Bed Fusion

Powder bed fusion (PBF) is a process in which thermal energy (such as a laser or electron beam) selectively fuses areas of a powder bed to form layer, and layers are built upon each other to create a part. One thing to note is that PBF covers both sintering and melting processes. The basic method of operation of all powder bed systems is the same: a recoating blade or roller deposits a thin layer of the powder onto the build platform, the powder bed surface is then scanned with a heat source which selectively heats the particles to bind them together. Once a layer or cross-section has been scanned by the heat source, the platform moves down to allow the process to begin again on the next layer. The final result is a volume containing one or more fused parts surrounded by unaffected powder. When the build is complete, the bed is fully raised to allow the parts to be removed from the unaffected powder and any required post processing to begin.

Selective laser sintering (SLS) is often used for manufacture of polymer parts and is good for prototypes or functional parts due to the properties produced, while the lack of support structures (the powder bed acts as a support) allows for the creation of pieces with complex geometries. The parts produced may have a grainy surface and inner porosity, meaning there is often a need for post processing.

Direct metal laser sintering (DMLS), selective laser melting (SLM) and electron beam powder bed fusion (EBPBF) are similar to SLS, except these processes create parts from metal, using a laser to bond powder particles together layer-by-layer. While SLM fully melts the metal particles, DMLS only heats them to the point of fusion whereby they join on a molecular level. Both SLM and DMLS require support structures due to the high heat inputs required by the process. These support structures are then removed in post processing ether manually or via CNC machining. Finally, the parts may be thermally treated to remove residual stresses.

Both DMLS and SLM produce parts with excellent physical properties - often stronger than the conventional metal itself, and good surface finishes. They can be used with metal superalloys and sometimes ceramics which are difficult to process by other means. However, these processes can be expensive and the size of the produced parts is limited by the volume of the 3D printing system used.

Sheet Lamination

Sheet lamination can be split into two different technologies, laminated object manufacturing (LOM) and ultrasonic additive manufacturing (UAM). LOM uses alternate layers of material and adhesive to create items with visual and aesthetic appeal, while UAM joins thin sheets of metal via ultrasonic welding. UAM is a low temperature, low energy process that can be used with aluminium, stainless steel and titanium.

VAT Photopolymerization

VAT photopolymerization can be broken down into two techniques; stereolithography (SLA) and digital light processing (DLP). These processes both create parts layer-by-layer through the use of a light to selectively cure liquid resin in a vat. SLA uses a single point laser or UV source for the curing process, while DLP flashes a single image of each full layer onto the surface of the vat. Parts need to be cleaned of excess resin after printing and then exposed to a light source to improve the strength of the pieces. Any support structures will also need to be removed and additional post-processing can be used to create a higher quality finish.

Ideal for parts with a high level of dimensional accuracy, these processes can create intricate details with a smooth finish, making them perfect for prototype production. However, as the parts are more brittle than fused deposition modelling (FDM) they are less suited to functional prototypes. Also, these parts are not suitable for outdoor use as the colour and mechanical properties may degrade when exposed to UV light from the sun. The required support structures can also leave blemishes that need post processing to remove.

The printing time depends on a number of factors, including the size of the part and the settings used for printing. The quality of the finished part is also important when determining printing time as higher quality items take longer to produce. 3D printing can take anything from a few minutes to several hours or days - speed, resolution and the volume of material are all important factors here.

The advantages of 3D printing include:

Bespoke, cost-effective creation of complex geometries:
This technology allows for the easy creation of bespoke geometric parts where added complexity comes at no extra cost. In some instances, 3D printing is cheaper than subtractive production methods as no extra material is used.
Affordable start-up costs:
Since no moulds are required, the costs associated with this manufacturing process are relatively low. The cost of a part is directly related to the amount of material used, the time taken to build the part and any post processing that may be required.
Completely customisable:
Because the process is based upon computer aided designs (CAD), any product alterations are easy to make without impacting the manufacturing cost.
Ideal for rapid prototyping:
Because the technology allows for small batches and in-house production, this process is ideal for prototyping, which means that products can be created faster than with more traditional manufacturing techniques, and without the reliance on external supply chains.
Allows for the creation of parts with specific properties:
Although plastics and metals are the most common materials used in 3D printing, there is also scope for creating parts from specially tailored materials with desired properties. So, for example, parts can be created with high heat resistance, water repellency or higher strengths for specific applications.

The disadvantages of 3D printing include:

Can have a lower strength than with traditional manufacture:
While some parts, such as those made from metal, have excellent mechanical properties, many other 3D printed parts are more brittle than those created by traditional manufacturing techniques. This is because the parts are built up layer-by-layer, which reduces the strength by between 10 and 50%.
Increased cost at high volume:
Large production runs are more expensive with 3D printing as economies of scale do not impact this process as they do with other traditional methods. Estimates suggest that when making a direct comparison for identical parts, 3D printing is less cost effective than CNC machining or injection moulding in excess of 100 units, provided the parts can be manufactured by conventional means.
Limitations in accuracy:
The accuracy of a printed part depends on the type of machine and/or process used. Some desktop printers have lower tolerances than other printers, meaning that the final parts may slightly differ from the designs. While this can be fixed with post-processing, it must be considered that 3D printed parts may not always be exact.
Post-processing requirements:
Most 3D printed parts require some form of post-processing. This may be sanding or smoothing to create a required finish, the removal of support struts which allow the materials to be built up into the designated shape, heat treatment to achieve specific material properties or final machining.

An STL file is a simple, portable format used by computer aided design (CAD) systems to define the solid geometry for 3D printable parts. An STL file provides the input information for 3D printing by modelling the surfaces of the object as triangles that share edges and vertices with other neighbouring triangles for the build platform. The resolution of the STL file impacts the quality of the 3D printed parts - if the file resolution is too high the triangle may overlap, if it is too low the model will have gaps, making it unprintable. Many 3D printers require an STL file to print from, however these files can be created in most CAD programs.

Due to the versatility of the process, 3D printing has applications across a range of industries, for example:

Aerospace

3D printing is used across the aerospace (and astrospace) industry due to the ability to create light, yet geometrically complex parts, such as blisks. Rather than building a part from several components, 3D printing allows for an item to be created as one whole component, reducing lead times and material wastage.

Automotive

The automotive industry has embraced 3D printing due to the inherent weight and cost reductions. It also allows for rapid prototyping of new or bespoke parts for test or small-scale manufacture. So, for example, if a particular part is no longer available, it can be produced as part of a small, bespoke run, including the manufacture of spare parts. Alternatively, items or fixtures can be printed overnight and are ready for testing ahead of a larger manufacturing run.

Medical

The medical sector has found uses for 3D printing in the creation of made-to-measure implants and devices. For example, hearing aids can be created quickly from a digital file that is matched to a scan of the patient's body. 3D printing can also dramatically reduce costs and production times.

Rail

The rail industry has found a number of applications for 3D printing, including the creation of customised parts, such as arm rests for drivers and housing covers for train couplings. Bespoke parts are just one application for the rail industry, which has also used the process to repair worn rails.

Robotics

The speed of manufacture, design freedom, and ease of design customisation make 3D printing perfectly suited to the robotics industry. This includes work to create bespoke exoskeletons and agile robots with improved agility and efficiency.

TWI has one of the most definitive ranges of 3D Printing services, including selective laser melting, laser deposition, wire and arc additive manufacturing, wire and electron beam additive manufacturing and EB powder bed fusion small-scale prototyping, and more.

Additive Manufacturing

TWI provides companies with support covering every aspect of metal additive manufacturing (AM), from simple feasibility and fabrication projects to full adoption and integration of metal AM systems.

Laser Metal Deposition

TWI has been developing LMD technology for the last ten years. For full details of our capabilities in this area, and to find out more about the process and the benefits it can bring to your business.

Selective Laser Melting

TWI has been developing selective laser melting technology for the last decade. Find out full details of our capabilities in this area and the benefits it can bring to your business.

Can 3D Printing be used for Mass Production?

While there have been great advances in 3D printing, it still struggles to match other manufacturing techniques for high volume production. Techniques such as injection moulding allow for much faster mass production of parts.

Where is 3D Printing Heading in the Future?

As 3D printing technology continues to improve it could democratise the manufacture of goods. With printers becoming faster, they will be able to work on larger scale production projects, while lowering the cost of 3D printing will help its use spread outside of industrial uses and into homes, schools and other settings.

Which 3D Printing Material is most Flexible?

Thermoplastic polyurethane (TPU) is commonly deemed to be the most flexible material available to the 3D printing industry. TPU possesses bendable and stretchy characteristics that many other filaments do not have.

Which 3D Printing Material is the Strongest?

Polycarbonate is seen as the strongest 3D printing material, with a tensile strength of 9,800 psi, compared to nylon, for example, with just 7,000 psi.

Why is 3D Printing Important?

3D printing is important for the many benefits it brings. It allows users to produce items that have geometries which are difficult or impossible for traditional methods to produce. It also allows users with a limited experience to edit designs and create bespoke, customised parts. On-demand 3D printing also saves on tooling costs and provides an advanced time-to-market. 3D printing is important for industries such as aerospace, where it can create lightweight yet complex parts, offering weight saving, the associated fuel reductions and a better environmental impact as a result. It is also important for the creation of prototypes that can advance industry.

Will 3D Printing Replace Traditional Manufacturing?

3D printing has the capability to disrupt traditional manufacturing through the democratisation of production along with the production of moulds, tools and other bespoke parts. However, challenges around mass production mean that 3D printing is unlikely to replace traditional manufacturing where high volume production of comparatively simple parts is required.

Are 3D Printing Fumes Dangerous?

3D printing fumes can be dangerous to your health as the process produces toxic filament fumes. These emissions are produced as the plastic filaments are melted to create the product layer-by-layer. However, correct procedures such as ensuring sufficient ventilation or using extractors can solve this issue.

What is 3D printing? How does a 3D printer work? Learn 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 cross-section of the 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 shapes using less material than traditional manufacturing methods.

Table of Contents

How Does 3D Printing Work?
3D Printing Industry
Examples of 3D Printing
3D Printing Technologies & Processes
Materials
Services

Jump to your field of interest:

Rapid Prototyping & Manufacturing
Automotive
Aviation
Construction
Consumer Products
Healthcare
Food
Education

Jump to process:

All Technologies & Processes
Vat Photopolymerisation
Material Jetting
Binder Jetting
Material Extrusion
Powder Bed Fusion
Sheet Lamination
Directed Energy Deposition

How Does 3D Printing Work?

It all starts with a 3D model. You can opt to create one from the ground up or download it from a 3D library.

3D Software

There are many different software tools available. From industrial grade to open source. We’ve created an overview on our 3D software page.

We often recommend beginners to start with Tinkercad. Tinkercad is free and works in your browser, you don’t have to install it on your computer. Tinkercad offers beginner lessons and has a built-in feature to export your model as a printable file e.g .STL or .OBJ.

Now that you have a printable file, the next step is to prepare it for your 3D printer. This is called slicing.

Slicing: From printable file to 3D Printer

Slicing basically means slicing up a 3D model into hundreds or thousands of layers and is done with slicing software.

When your file is sliced, it’s ready for your 3D printer. Feeding the file to your printer can be done via USB, SD or Wi-Fi. Your sliced file is now ready to be 3D printed layer by layer.

3D Printing Industry

Adoption of 3D printing has reached critical mass as those who have yet to integrate additive manufacturing somewhere in their supply chain are now part of an ever-shrinking minority. Where 3D printing was only suitable for prototyping and one-off manufacturing in the early stages, it is now rapidly transforming into a production technology.

Most of the current demand for 3D printing is industrial in nature. Acumen Research and Consulting forecasts the global 3D printing market to reach $41 billion by 2026.

As it evolves, 3D printing technology is destined to transform almost every major industry and change the way we live, work, and play in the future.

Examples of 3D Printing

3D printing encompasses many forms of technologies and materials as 3D printing is being used in almost all industries you could think of. It’s important to see it as a cluster of diverse industries with a myriad of different applications.

A few examples:

– consumer products (eyewear, footwear, design, furniture)
– industrial products (manufacturing tools, prototypes, functional end-use parts)
– dental products
– prosthetics
– architectural scale models & maquettes
– reconstructing fossils
– replicating ancient artefacts
– reconstructing evidence in forensic pathology
– movie props

Rapid Prototyping & Rapid Manufacturing

Companies have used 3D printers in their design process to create prototypes since the late seventies. Using 3D printers for these purposes is called rapid prototyping.

Why use 3D Printers for Rapid Prototyping?
In short: it’s fast and relatively cheap. From idea, to 3D model to holding a prototype in your hands is a matter of days instead of weeks. Iterations are easier and cheaper to make and you don’t need expensive molds or tools.

Besides rapid prototyping, 3D printing is also used for rapid manufacturing. Rapid manufacturing is a new method of manufacturing where businesses use 3D printers for short run / small batch custom manufacturing.

Automotive

Car manufacturers have been utilizing 3D printing for a long time. Automotive companies are printing spare parts, tools, jigs and fixtures but also end-use parts. 3D printing has enabled on-demand manufacturing which has lead to lower stock levels and has shortened design and production cycles.

Automotive enthusiasts all over the world are using 3D printed parts to restore old cars. One such example is when Australian engineers printed parts to bring a Delage Type-C back to life. In doing so, they had to print parts that were out of production for decades.

Aviation

The aviation industry uses 3D printing in many different ways. The following example marks a significant 3D printing manufacturing milestone: GE Aviation has 3D printed 30,000 Cobalt-chrome fuel nozzles for its LEAP aircraft engines. They achieved that milestone in October of 2018, and considering that they produce 600 per week on forty 3D printers, it’s likely much higher than that now.

Around twenty individual parts that previously had to be welded together were consolidated into one 3D printed component that weighs 25% less and is five times stronger. The LEAP engine is the best selling engine in the aerospace industry due to its high level of efficiency and GE saves $3 million per aircraft by 3D printing the fuel nozzles, so this single 3D printed part generates hundreds of millions of dollars of financial benefit.

GE’s fuel nozzles also made their way into the Boeing 787 Dreamliner, but it’s not the only 3D printed part in the 787. The 33-centimeter-long structural fittings that hold the aft kitchen galley to the airframe are 3D printed by a company called Norsk Titanium. Norsk chose to specialize in titanium because it has a very high strength-to-weight ratio and is rather expensive, meaning the reduction in waste enabled by 3D printing has a more significant financial impact than compared to cheaper metals where the costs of material waste are easier to absorb. Rather than sintering metal powder with a laser like most metal 3D printers, the Norsk Merke 4 uses a plasma arc to melt a metal wire in a process called Rapid Plasma Deposition (a form of Directed Energy Deposition) that can deposit up to 10kg of titanium per hour. A 2kg titanium part would generally require a 30kg block of titanium to machine it from, generating 28kg of waste, but 3D printing the same part requires only 6kg of titanium wire.

Construction

Is it possible to print a building? – yes it is. 3D printed houses are already commercially available. Some companies print parts prefab and others do it on-site.

Most of the concrete printing stories we look at on this website are focused on large scale concrete printing systems with fairly large nozzles for a large flow rate. It’s great for laying down concrete layers in a fairly quick and repeatable manner. But for truly intricate concrete work that makes full use of the capabilities of 3D printing requires something a little more nimble, and with a finer touch.

Consumer Products

When we first started blogging about 3D printing back in 2011, 3D printing wasn’t ready to be used as a production method for large volumes. Nowadays there are numerous examples of end-use 3D printed consumer products.

Footwear

Adidas’ 4D range has a fully 3D printed midsole and is being printed in large volumes. We did an article back then, explaining how Adidas were initially releasing just 5,000 pairs of the shoes to the public, and had aimed to sell 100,000 pairs of the AM-infused designs by 2018.

With their latest iterations of the shoe, it seems that they have surpassed that goal, or are on their way to surpassing it. The shoes are available all around the world from local Adidas stores and also from various 3rd party online outlets.

Eyewear

The market of 3D printed eyewear is forecasted to reach $3.4 billion by 2028. A rapidly increasing section is that of end-use frames. 3D printing is a particularly suitable production method for eyewear frames because the measurements of an individual are easy to process in the end product.

But did you know it’s also possible to 3D print lenses? Traditional glass lenses don’t start out thin and light; they’re cut from a much larger block of material called a blank, about 80% of which goes to waste. When we consider how many people wear glasses and how often they need to get a new pair, 80% of those numbers is a lot of waste. On top of that, labs have to keep huge inventories of blanks to meet the custom vision needs of their clients. Finally, however, 3D printing technology has advanced enough to provide high-quality, custom ophthalmic lenses, doing away with the waste and inventory costs of the past. The Luxexcel VisionEngine 3D printer uses a UV-curable acrylate monomer to print two pairs of lenses per hour that require no polishing or post-processing of any kind. The focal areas can also be completely customized so that a certain area of the lens can provide better clarity at a distance while a different area of the lens provides better vision up close.

Jewelry

There are two ways of producing jewelry with a 3D printer. You can either use a direct or indirect production process. Direct refers to the creation of an object straight from the 3D design while indirect manufacturing means that the object (pattern) that is 3D printed eventually is used to create a mold for investment casting.

Healthcare

It’s not uncommon these days to see headlines about 3D printed implants. Often, those cases are experimental, which can make it seem like 3D printing is still a fringe technology in the medical and healthcare sectors, but that’s not the case anymore. Over the last decade, more than 100,000 hip replacements have been 3D printed by GE Additive.

The Delta-TT Cup designed by Dr. Guido Grappiolo and LimaCorporate is made of Trabecular Titanium, which is characterized by a regular, three-dimensional, hexagonal cell structure that imitates trabecular bone morphology. The trabecular structure increases the biocompatibility of the titanium by encouraging bone growth into the implant. Some of the first Delta-TT implants are still running strong over a decade later.

Another 3D printed healthcare component that does a good job of being undetectable is the hearing aid. Nearly every hearing aid in the last 17 years has been 3D printed thanks to a collaboration between Materialise and Phonak. Phonak developed Rapid Shell Modeling (RSM) in 2001. Prior to RSM, making one hearing aid required nine laborious steps involving hand sculpting and mold making, and the results were often ill-fitting. With RSM, a technician uses silicone to take an impression of the ear canal, that impression is 3D scanned, and after some minor tweaking the model is 3D printed with a resin 3D printer. The electronics are added and then it’s shipped to the user. Using this process, hundreds of thousands of hearing aids are 3D printed each year.

Dental

In the dental industry, we see molds for clear aligners being possibly the most 3D printed objects in the world. Currently, the molds are 3D printed with both resin and powder based 3D printing processes, but also via material jetting. Crowns and dentures are already directly 3D printed, along with surgical guides.

Bio-printing

As of the early two-thousands 3D printing technology has been studied by biotech firms and academia for possible use in tissue engineering applications where organs and body parts are built using inkjet techniques. Layers of living cells are deposited onto a gel medium and slowly built up to form three dimensional structures. We refer to this field of research with the term: bio-printing.

Food

Additive manufacturing invaded the food industry long time ago. Restaurants like Food Ink and Melisse use this as a unique selling point to attract customers from across the world.

Education

Educators and students have long been using 3D printers in the classroom. 3D printing enables students to materialize their ideas in a fast and affordable way.

While additive manufacturing-specific degrees are fairly new, universities have long been using 3D printers in other disciplines. There are many educational courses one can take to engage with 3D printing. Universities offer courses on things that are adjacent to 3D printing like CAD and 3D design, which can be applied to 3D printing at a certain stage.

In terms of prototyping, many university programs are turning to printers. There are specializations in additive manufacturing one can attain through architecture or industrial design degrees. Printed prototypes are also very common in the arts, animation and fashion studies as well.

Types of 3D Printing Technologies and Processes

The American Society for Testing and Materials (ASTM), developed a set of standards that classify additive manufacturing processes into 7 categories. These are:

Vat Photopolymerisation
1. Stereolithography (SLA)
2. Digital Light Processing (DLP)
3. Continuous Liquid Interface Production (CLIP)
Material Jetting
Binder Jetting
Material Extrusion
1. Fused Deposition Modeling (FDM)
2. Fused Filament Fabrication (FFF)
Powder Bed Fusion
1. Multi Jet Fusion (MJF)
2. Selective Laser Sintering (SLS)
3. Direct Metal Laser Sintering (DMLS)
Sheet Lamination
Directed Energy Deposition

Vat Photopolymerisation

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

Vat photopolymerisation schematics. Image source: lboro.ac.uk

Stereolithography (SLA)

SLA was invented in 1986 by Charles Hull, who also at the time founded the company, 3D Systems. Stereolithography employs a vat of liquid 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 fuses 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. Depending on the object & print orientation, SLA often requires the use of support structures.

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 SLA, the key difference is the light source. DLP utilizes other light sources like arc lamps. DLP is relatively quick compared to other 3D printing technologies.

Continuous Liquid Interface Production (CLIP)

One of the fastest processes using Vat Photopolymerisation is called CLIP, short for Continuous Liquid Interface Production, developed by 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 passes 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.

Components printed with Carbon’s technology are on par with injection molded parts. Digital Light Synthesis produces consistent and predictable mechanical properties, creating parts that are truly isotropic.

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 and then hardened by UV light.

Material Jetting schematics. Image source: custompartnet.com