What is 3D printing?

3D printing is an additive technology used to manufacture parts. It is ‘additive’ in that it doesn’t require a block of material or a mold to manufacture physical objects, it simply stacks and fuses layers of material. It’s typically fast, with low fixed setup costs, and can create more complex geometries than ‘traditional’ technologies, with an ever-expanding list of materials. It is used extensively in the engineering industry, particularly for prototyping and creating lightweight geometries.

‘3D printing’ is commonly associated with maker culture, hobbyists and amateurs, desktop printers, accessible printing technologies like FDM and low-cost materials such as ABS and PLA (we’ll explain all those acronyms below). This is largely attributable to the democratization of 3D printing through affordable desktop machines that sprung from the RepRap movement, like the original MakerBot and Ultimaker, which also led to the explosion of 3D printing in 2009.

By contrast, additive manufacturing (AM) is almost always associated with commercial and industrial applications.

‘Rapid prototyping’ is another phrase that’s sometimes used to refer to 3D printing technologies. This dates back to the early history of 3D printing when the technology first emerged. In the 1980s, when 3D printing techniques were first invented, they were referred to as rapid prototyping technologies because back then the technology was only suitable for prototypes, not production parts.

In recent years, 3D printing has matured into an excellent solution for many kinds of production parts, and other manufacturing technologies (like CNC machining) have become cheaper and more accessible for prototyping. So while some people still use ‘rapid prototyping’ to refer to 3D printing, the phrase is evolving to refer to all forms of very fast prototyping.

3D printing began as an idea for accelerating industrial product development through faster prototyping. Even though there were a few patents beforehand, Chuck Hull is typically credited with the invention of the 3D printer via his Stereolithography Apparatus (SLA), patented in 1984.

Foundations

Despite Chuck’s fame, multiple technologies were being developed in parallel in the late 1980s, and there were several companies founded in this period that was critical to the development of the technology.

• 1981 - the first patent for a device using UV light to cure photopolymers was awarded to Hideo Kodama in Japan. He designed it for ‘rapid prototyping’ as it was intended for making models and prototypes, but there was no interest and the patent was abandoned.
• 1984 - French inventors Alain Le Mehaute, Olivier de Witte, and Jean Claude André submitted a patent in which, like Hideo’s, UV light was used to cure photopolymers. General Electric abandoned the patent citing a lack of significant business potential.
• 1984 - only a few weeks after Le Mehaute, American Charles ‘Chuck’ Hull filed his own patent for an ‘Apparatus for Production of Three-Dimensional Objects by Stereolithography’, thus also coining the term ‘stereolithography’ (SLA).
• 1987 - Hull invented the STL file, and in the same year founded 3D Systems.
• 1987 - American Carl Deckard filed a patent for Selective Laser Sintering (SLS), and in the same year co-founded Desktop Manufacturing (DTM) Corp. (acquired by 3D Systems in 2001).
• 1989 - American S. Scott Crump submits a patent for Fused Deposition Modeling (FDM), and in the same year founded Stratasys with his wife.

Commercialization

From the late 1980s to the early 1990s the industry underwent very rapid commercialization. The first machines were big and expensive and their makers competed for industrial prototyping contracts with mass-market manufacturers in the automotive, aerospace, health, and consumer goods industries.

• 1987 - 3D Systems released the first commercial SLA printer, the ‘SLA-1’.
• 1992 - The FDM patent was finally granted to Stratasys, which led them to release the first FDM printer, the ‘3D Modeler’.
• 1992 - DTM released the first commercial SLS printer, the ‘Sinterstation 2000’
• 1994 - German company Electro Optical Systems (EOS), founded in 1989, unveiled its ‘EOSINT M160’, the first commercial metal 3D printer

Democratization

In the early 2000s the fierce competition for profits, developments in material science, and the ending of many patents created an environment in which 3D printing finally became affordable for the masses. This was the decade that 3D printing took off in the popular imagination - manufacturing, which had always been the domain of heavy industry and big money, came to the people.

• 2005 - The open-source RepRap Project (for ‘Replicated Rapid Prototyper’) launched with the aim of creating self-replicating 3D printers capable of printing their own parts, causing popular interest in the technology to skyrocket.
• 2009 - Key FDM patents fell into the public domain and MakerBot launched their desktop 3D printer, the ‘Cupcake CNC’. It cost hundreds of dollars, not thousands, and all components were downloadable from Thingiverse, a website dedicated to the sharing of user-created digital design files.
• 2012 - Formlabs release the ‘Form 1’, the first affordable SLA printer, through a record-breaking Kickstarter campaign that raised $2.95 million in funding.
• 2013 - Protolabs Network launches as a peer-to-peer 3D printing service, allowing mass transactions between people buying prints and people with machines. It quickly grew to be the single biggest 3D printing platform in the world with over 50,000 printing ‘hubs’, before pivoting to focus on helping its business customers by making all forms of custom manufacturing more accessible.
• 2014 - Key SLS patents fell into the public domain, leading to a whole crop of companies making smaller and more affordable SLS printers.

Maturity

From 2018 the hype around 3D printing had largely disappeared from mass media, but interest in commercial applications for businesses of all sizes has never been higher. Today there are thousands of companies producing printers and offering all sorts of services leveraging 3D printing technology.

Learn more about the history of 3D printing

There are many articles out there, most are just fun reads. For those looking to really delve deep into history, Wikipedia and Wohler Associates are the best resources.

• Wikipedia - 3D printing
• Wohlers Report 2016 - History of Additive Manufacturing

Additive manufacturing has only been around since the 1980s, so the manufacturing methods developed before it are often referred to as traditional manufacturing. To understand the major differences between additive and traditional manufacturing, let’s categorize all methods into 3 groups: additive, subtractive and formative manufacturing.

Additive manufacturing

Additive manufacturing builds up 3D objects by depositing and fusing 2D layers of material.

This method has almost no startup time or costs, making it ideal for prototyping. Parts can be made rapidly and discarded after use. Parts can also be produced in almost any geometry, which is one of the core strengths of 3D printing.

One of the biggest limitations of 3D printing is that most parts are inherently anisotropic or not fully dense, meaning they usually lack the material and mechanical properties of parts made via subtractive or formative techniques. Due to fluctuations in cooling or curing conditions, different prints of the same part are also prone to slight variations, which puts limitations on consistency and repeatability.

Subtractive manufacturing

Subtractive manufacturing, such as milling and turning, creates objects by removing (machining) material from a block of solid material that’s also often referred to as a ‘blank’.

Almost any material can be machined in some way, making it a widely used technique. Because of the amount of control over every aspect of the process this method is capable of producing incredibly accurate parts with high repeatability. Most designs require Computer Aided Manufacturing (CAM) to plot customized tool paths and efficient material removal, which adds setup time and costs, but for the majority of designs, it’s the most cost-effective method of production.

The major limitation of subtractive manufacturing is that the cutting tool must be able to reach all surfaces to remove material, which limits design complexity quite a lot. While machines like 5-axis machines eliminate some of these restrictions, complex parts still need to be re-orientated during the machining process, adding time and cost. Subtractive manufacturing is also a wasteful process due to the large amounts of material removed to produce the final part geometry.

Formative manufacturing

Formative manufacturing, such as injection molding and stamping, creates objects by forming or molding materials into shape with heat and/or pressure.

Formative techniques are designed to reduce the marginal cost of producing individual parts, but the creation of unique molds or machines used in the production process means setup costs are very, very high. Regardless, these techniques can produce parts in a large range of materials (both metals and plastics) with close to flawless repeatability, so for high volume production, they’re almost always the most cost-efficient.

How these methods compare

Manufacturing is complex, and there are too many dimensions for comprehensively comparing each method against all others. It is near impossible to optimize all at once for cost, speed, geometric complexity, materials, mechanical properties, surface finish, tolerances, and repeatability.

In such complex situations heuristics and rules of thumb are more valuable:

• Additive manufacturing is best for low volumes, complex designs, and when speed is essential.
• Subtractive manufacturing is best for medium volumes, simple geometries, tight tolerances, and hard materials
• Formative manufacturing is best for the high-volume production of identical parts.

Cost per part is usually the governing factor determining which manufacturing process is best. As a rough approximation the unit costs per method can be visualized like this:

Learn more about 3D printing vs CNC machining.

3D printing is becoming cheaper every year and in some instances, it is starting to compete with injection molding for cost efficiency. However it’s usually 3D printing and CNC machining that are considered interchangeable for particular jobs, so we’ve written a thorough guide comparing them side by side. Read more about 3D printing vs CNC machining.

With so many different 3D printing technologies on the market, it can be hard to understand the whole landscape. The International Organization for Standardization created the ISO/ASTM standard 52900 to standardize the exploding terminology around 3D printing and we’ve pulled together the most-used language into this glossary of 3D printing terms.

3D printers can be categorized into one of several types of processes:

1. Vat Polymerization: liquid photopolymer is cured by light
2. Material Extrusion: molten thermoplastic is deposited through a heated nozzle
3. Powder Bed Fusion: powder particles are fused by a high-energy source
4. Material Jetting: droplets of liquid photosensitive fusing agent are deposited on a powder bed and cured by light
5. Binder Jetting: droplets of liquid binding agent are deposited on a bed of granulated materials, which are later sintered together
6. Direct Energy Deposition: molten metal simultaneously deposited and fused
7. Sheet Lamination: individual sheets of material are cut to shape and laminated together

There are seven main 3D printing processes. Within each type of process there are unique technologies, and for every unique technology there are also many different brands selling similar printers.

Vat photopolymerization

Photopolymerization is the process of a photopolymer resin being exposed to certain wavelengths of light and becoming solid.

Stereolithography (SLA), direct light processing (DLP) and continuous direct light processing (CDLP) are additive manufacturing processes that fall under the category of vat photopolymerization. In SLA, an object is created by selectively curing a polymer resin layer-by-layer using an ultraviolet (UV) laser beam. DLP is similar to SLA but uses a digital light projector screen to flash a single image of each layer all at once. CDLP is a lot like DLP but relies on the continuous upward motion of the build plate. All vat photopolymerization processes are good for producing fine details and smooth surface finishes, making them ideal for jewelry and medical applications.

Benefits

• Smooth surface
• Fine details
• Good for prototyping of IM

Limitations

• Brittle
• Usually requires supports
• UV sensitive
• Extensive post processing required

Powder bed fusion

Powder bed fusion (PBF) technologies use a heat source to induce fusion (sintering or melting) between the particles of a plastic or metal powder one layer at a time. Selective Laser Sintering (SLS), electron beam melting (EBM) and multi jet fusion (MJF) all fall within this technology. The metal 3D printing processes selective laser melting (SLM) and direct metal laser sintering (DMLS) also use powder bed fusion to selectively bind metal powder particles.

Benefits

• Strong parts (nylon)
• Complex geometry
• Scalable (fits size)
• No support

Limitations

• Longer production time
• Higher cost (machines, material, operation)

Material extrusion

Material extrusion technologies squeeze a material through a nozzle and onto a build plate, layer by layer. Fused deposition modeling (FDM) falls under this category and is the most widely used 3D printing technology.

Benefits

• Fast
• Low cost
• Common thermoplastics

Limitations

• Rough surface finish
• Anisotropic
• Usually requires supports
• Not scalable
• Limited accuracy

Material jetting

Material jetting technologies use UV light or heat to harden photopolymers, metals or wax, building parts one layer at a time. Nano particle jetting (NPJ) and Drop-on-demand (DOD) are two other types of material jetting.

Benefits

• Realistic prototypes
• Excellent details
• High accuracy
• Smooth surface finish

Limitations

• High cost
• Brittle mechanical properties

Binder Jetting

Binder jetting uses an industrial printhead to deposit a binding adhesive agent onto thin layers of powder material. Unlike the other 3D printing technologies, binder jetting does not require heat.

Benefits

• Full-color options
• Range of materials
• No support
• No warping or shrinking

Limitations

• Low part strength
• Less accurate than material jetting

Direct energy deposition

Direct energy deposition (DED) creates 3D objects by melting powder material as it is deposited. It is mostly used with metal powders or wire and is often referred to as metal deposition. Laser engineered net shape (LENS) and Electron Beam Additive Manufacture (EBAM) also fall within this category.

Benefits

• Strong parts
• Range of materials
• Larger parts

Limitations

• High cost
• Poor surface finish

Sheet lamination

This technology stacks and laminates thin sheets of material to make parts. There are a few different types of lamination to choose from: bonding, ultrasonic welding or brazing.

Benefits

• Fast
• Low cost
• No support structures necessary
• Multi-material layers

Limitations

• Post processing is required
• Limited materials
• Finishing may vary

The whole landscape of additive manufacturing technologies can be summarized in a simple tree-diagram:

Click here to download a high-resolution version of this poster.

Our article on The Seven Official Types Of 3D Printers gives a broad overview of how each type of printer works, the materials available, the price and speed of printing, geometric properties (size, complexity & resolution), mechanical properties (accuracy, strength & surface finish) and common applications.

Looking for more in-depth information on the topic? We also wrote a handbook on 3D printing. If you’re a professional looking to truly master the key aspects of 3D printing, this book is for you.

Selecting the optimal 3D printing process for a particular part can be difficult as there’s often more than one suitable process but each one will produce subtle variations in cost and output. Generally there are three key aspects to consider:

• The required material properties: strength, hardness, impact strength, etc.
• The functional & visual design requirements: smooth surface, strength, heat resistance, etc.
• The capabilities of the 3D printing process: accuracy, build size, etc.

These correspond to the three most common methods for selecting the right process:

• By required material
• By required functionality or visual appearance
• By required accuracy or build size

For an in-depth look at how to use these methods read our complete guide to Selecting the right 3D printing process. The following comparison guides will also help inform your decision.

• HP MJF vs. SLS: A 3D printing technology comparison
• Industrial SLA/DLP vs. desktop SLA/DLP
• Industrial FDM vs. desktop FDM

The number of available 3D printing materials grows rapidly every year as market demand for specific material and mechanical properties spurs advancements in material science. This makes it impossible to give a complete overview of all 3D printing materials, but each 3D printing process is only compatible with certain materials so there are some easy generalizations to make.

Thermoplastic and thermoset polymers are by far the most common 3D printing materials, but metals, composites and ceramics can also be 3D printed.

Another way of categorizing materials is by their properties: cheap, chemically resistant, dissolvable, flexible, durable, heat resistant, rigid, water resistant, UV resistant. Many industrial applications require durable plastics such as Nylon 12, and most hobbyist applications use either PLA or ABS, which are the most common materials used in FDM 3D printing.

For a more thorough overview of each of the main 3D printing materials see these articles.

• FDM 3D printing materials compared
• PLA vs. ABS: What’s the difference?
• SLA 3D printing materials compared
• 3D printed injection molds: Materials compared

3D printing starts with software and there are many different programs to aid with each stage of the design and printing process, from 3D modelling, to print simulations and slicer programs.

The two main methods of 3D modelling are ‘solid modelling’ and ‘surface modelling’, and there are different CAD software packages for each approach. Solid modelling refers to the creation of virtual objects through defining and joining 3D shapes that are usually predefined and to which refined surface details are added later. Surface modelling is similar except the designer starts with 2D surfaces and shapes them in ‘freeform’ to create 3D shapes.

Both approaches can produce exactly the same output, but solid modelling is faster for simple and non-organic shapes, whereas surface modelling is faster for more organic shapes. SolidWorks, Fusion 360 and Rhino 3D are the most popular software with professionals, and there are many free programs for amateurs.

Other useful 3D printing software include print simulation tools and file error fixers.

The exact best practices and rules of thumb vary between the different 3D printing technologies, but there are certain features you always need to pay attention to:

• Supported wall thickness
• Unsupported wall thickness
• Supports and overhangs
• Embossed and engraved details
• Horizontal bridges
• Holes
• Connecting or moving parts
• Escape holes
• Minimum feature size
• Minimum pin diameter
• Maximum tolerance

The process-specific design rules for each of these features are summarized in the graphic below:

Click here to download a high-resolution version of this poster.

3D printing is exceptionally useful for prototyping. Speed is everything in prototyping, and the ability to move from CAD to print with close to zero set up costs means 3D printers can produce parts fast and have great unit economics for single-part and small runs.

For printing production parts, speed and price are also important, but the characteristics most commonly exploited are design freedom and ease of customization. In aerospace and automotive, topology optimized structures with a high strength-to-weight ratio are used for high-performance parts, and components that previously required assembly can be consolidated into a single part. In healthcare, customization is critical - most hearing aids manufactured in the US are made almost exclusively using 3D printing. In manufacturing, low-run injection molds can be 3D printed from stiff, heat-resistant plastics instead of machined from metal, making them much cheaper and faster to produce.

There are many applications for 3D printing in the medical industry, and each year doctors and scientists come up with new and creative ways to use this fast-growing technology. The speed and versatility of 3D printing makes it perfect for developing customized prosthetics and implants and patient-specific replicas of bones, organs and blood vessels. It is also used for 3D printing surgical tools, anatomical models, personalized medical equipment and a range of other life-saving innovations.

In the automotive industry, automakers use 3D printing to test form and fit, to experiment with aesthetic finishes and make sure that all parts operate and interact as intended. It also provides a flexible solution for the quick turnaround of jigs, fixtures and grips; creating bellows; engineering complex ducting; and rapidly manufacturing complex, lightweight mounting brackets.

There are a few reasons that so many designers use 3D printing to create jewelry. The technology allows jewelers to produce very complex, highly customizable designs, sidestepping some of the limitations of previously popular jewelry making techniques such as CNC machining, handcrafting and lost-wax casting. Today, precious metals can be 3D printed in a variety of patterns and designs quickly and cost effectively.

To learn more about the many different applications of 3D printing, check out these articles.

• 3D printed rapid tooling
• 3D printing for grips, jigs and fixtures
• 3D printing low-run injection molds
• Producing low-cost cast metal parts using 3D printing

3D printing is an exceptional tool for custom parts and rapid prototyping with a unique set of advantages but also lags behind traditional manufacturing in some ways. The key benefits and limitations can be summarized as follows:

Benefits

• Very low start-up costs
• Very quick turnaround
• Large range of available materials
• Design freedom at no extra cost
• Each and every part can easily be customized

Limitations

• Less cost-competitive at higher volumes
• Limited accuracy & tolerances
• Lower strength & anisotropic material properties
• Requires post-processing & support removal

For a more thorough overview read our article about the benefits and limitations of 3D printing

So where is 3D printing today? Is the hype over? Yes, and now the technology is reaching maturity. We’ve produced a 3D Printing Trend Report every year since 2017. Over those years we’ve watched the technology reach the height of the hype cycle, drop through the ‘trough of disillusionment, and bounce back to where it is now - on the ‘slope of enlightenment.

The hype of the previous years was based on the idea of widespread consumer adoption. This was a misleading interpretation of where the technology could add value to the world. The most promising applications of 3D printing are in very specific roles in the world of manufacturing.

To understand where 3D printing is headed in the next few years, consult the most recent version of our annual 3D printing trend report.

• 3D Printing Trend Report - Most Recent Report
• 3D Printing Trend Report - Past Trends

3D printing has come a long way since its inception and it’s now very easy to get something 3D printed quickly and affordably.

3D printing has come a long way since its inception and it’s now very easy to get something 3D printed very fast for pretty cheap.

Should you buy your own 3D printer or use an online service? It’s an important decision to make, so we’ve collected arguments for both sides to help you make the right choice.

If you’ve decided it’s a good idea to buy your own 3D printer, you may be overwhelmed by the range of choices now available. To help people make sense of the 3D printer market, we reached out to our entire customer base and our global network of 3D printing service providers to find out about the 3D printers they own and their experiences in using them.

With reviews from more than 10,000 3D printer owners, who’ve completed about 1.48 million prints on 650+ different 3D printer models, our research is the most comprehensive 3D Printer Guide available.

Read our guide to finding the best 3D printer for you.

At Protolabs Network, we’re building the smartest manufacturing solution on the planet. One of our main offerings is our 3D Printing service.

When you upload a part to our online 3D printing service our proprietary pricing algorithm gives you a quote in a matter of seconds. As you specify your requirements the price will update automatically, and if you’re happy with the price and the lead times you can submit the order in just a few minutes.

If you have more questions about 3D printing, check out our Knowledge Base and filter on ‘3D printing’ to see everything all at once.

If you’re interested in diving deeper into any of the topics covered above, we literally wrote the book on 3D printing. If you’re a professional looking to truly master the key aspects of 3D printing, this book is for you. It provides practical advice on selecting the right technology and how-to design for 3D printing, based upon the first-hand experience from the industry’s leading experts.

Here’s what Tony Fadell (creator of the iPod and founder of Nest) had to say about it:

“The Handbook” will help to guide you on your own path as you look to leverage 3D printing and its potential to create your own breakthrough products, that hopefully will change the world. Every designer and engineer should keep it close as it paves your way into new manufacturing technologies that will spur your creativity and unlock your ideas as they become reality. Creation is changing, manufacturing is changing and design is changing, turn the page, it’s time to stay ahead…

If you’re ready to purchase, The 3D Printing Handbook is available on Amazon. Or, if you like, you can download the first two chapters for free first.

Protolabs Network’s online manufacturing service offers more than just 3D printing. We also offer CNC machining, injection molding, and sheet metal fabrication, and to try to help our customers understand all these technologies we’ve written guides similar to this one for each of them.

Learn more about other manufacturing technologies