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Understanding 3d printing


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:

  1. Vat Photopolymerisation
    1. Stereolithography (SLA)
    2. Digital Light Processing (DLP)
    3. Continuous Liquid Interface Production (CLIP)
  2. Material Jetting
  3. Binder Jetting
  4. Material Extrusion
    1. Fused Deposition Modeling (FDM)
    2. Fused Filament Fabrication (FFF)
  5. Powder Bed Fusion
    1. Multi Jet Fusion (MJF)
    2. Selective Laser Sintering (SLS)
    3. Direct Metal Laser Sintering (DMLS)
  6. Sheet Lamination
  7. 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

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 required shape. After the print is finished, the remaining powder is cleaned off which often can be re-used printing the next object. This technology was first developed at the Massachusetts Institute of Technology in 1993.

Binder Jetting schematics

Material Extrusion

Fused Deposition Modeling (FDM)

FDM schematics (Image credit: Wikipedia, made by user Zureks)

FDM works using a plastic filament which is unwound from a spool and is supplied 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. The object is produced by extruding melted material to form layers as the material hardens immediately after extrusion from the nozzle.

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.

Powder Bed Fusion

Selective Laser Sintering (SLS)

SLS uses a high power laser to fuse small particles of powder into a mass that has the desired three dimensional shape. The laser selectively fuses powder by first scanning the cross-sections (or layers) 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 schematics (Image credit: Wikipedia from user Materialgeeza)

Multi Jet Fusion (MJF)

Multi Jet Fusion technology was developed by Hewlett Packard and works with a sweeping arm which deposits a layer of powder and then another arm equipped with inkjets which selectively applies a binder agent over the material. The inkjets also deposit a detailing agent around the binder to ensure precise dimensionality and smooth surfaces. Finally, the layer is exposed to a burst of thermal energy that causes the agents to react.

Direct Metal Laser Sintering (DMLS)

DMLS is basically the same as SLS, but uses metal powder instead. All unused powder remains as it is and becomes a support structure for the object. Unused powder can be re-used for the next print.

Due to of increased laser power, DMLS has evolved into a laser melting process. Read more about that and other metal technologies on our metal technologies overview page.

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.

Simplified schematics of ultrasonic sheet metal process (Image credit: Wikipedia from user Mmrjf3)

Directed Energy Deposition

This process is mostly used in the 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.

Directed Energy Deposition with metal powder and laser melting (Image credit: Merlin project)

Materials

Multiple materials can be used in additive manufacturing: plastics, metals, concrete, ceramics, paper and certain edibles (e.g. chocolate). Materials are often produced in wire feedstock a.k.a. filament, powder form or liquid resin. Learn more about our featured materials on our materials page.

Services

Looking to implement 3D printing in your production process? Get a quote for a custom part or order samples on our 3D print service page.

3D Printing Basics

3D Printing Basics

3D printing is any one of many processes in which a part is additively created by introducing or bonding additional material. 3D printed objects can be geometrically complex and are ideal in a wide variety of manufacturing applications. Machines can cost anywhere from hundreds to millions of dollars and utilize a wide variety of technologies to print parts.

Introduction to 3D Printing

According to the Wohler's Report, the global 3D printing industry is expected to exceed $21B in worldwide revenue by 2020. Much of this growth comes from an explosion in using 3D printing in manufacturing, something previously thought impossible when the process caught on. New materials, processes, and companies are popping up by the minute, all making promises about the unrivaled properties their parts can achieve. All this adds up to an industry that can be hard to understand.

In this track, we're getting back to the basics. What is 3D printing? What are the main technologies out there today? How much do industrial 3D printers cost? You can learn all this in our 3D printing introduction.

    • What is 3D Printing?
    • 3D Printer Types & Technologies
    • Understanding 3D Printer Cost
    • Different 3D Printing Materials
    • What is Atomic Diffusion Additive Manufacturing (ADAM)?
    • What is Binder Jetting?
    • What is Digital Light Processing (DLP)?
    • What is Direct Metal Laser Sintering (DMLS)?
    • What is Directed Energy Deposition (DED)?
    • What is Electron Beam Melting (EBM)?
    • What is Fused Deposition Modeling (FDM)?
    • What is Multijet Printing (MJP)?
    • What is Selective Laser Sintering (SLS)?
    • What is Stereolithography (SLA)?
    • 3D Printing Software
    • 3D Printing Materials
    • 3D Printing Process

What is 3D printing and how it can be used! Interesting!

What is 3D printing

3D printing technology was patented in the 80s of the last century, but gained popularity relatively recently. New, promising techniques have been developed and the possibilities of 3D technologies have reached a completely new level. However, to this day, the technique is not known in all circles, and not everyone is aware of what 3D printing is. In today's article, we will try to explain in detail and in an accessible way what 3D printing is and where it is used.

In short, 3D printing is a technique for manufacturing three-dimensional products based on digital models. Regardless of the specific technology, the essence of the process is the gradual layer-by-layer reproduction of objects.
This process uses a special device - a 3D printer, which prints certain types of materials. More details about it are written here. Other names for the technology are rapid prototyping or additive manufacturing. Often the phrase "additive technologies" is used in the meaning of "3D technologies".

3D printing steps

To make it clearer what 3D printing is, let's take a look at the playback process step by step. Below are the specific stages of 3D printing. How it works:

  • 3D modeling of the required object is performed according to certain rules;
  • The file with the digital model is loaded into the slicer program, which generates the control code for the 3D printer;
  • Sets required 3D printing options;
  • The code is written to a removable memory that connects to the 3D printer;
  • 3D model reproduced.

Objects are reproduced gradually. According to the required shape, the selected material is applied layer by layer, forming the finished product. It is worth noting that the possibilities of 3D printing are almost limitless, that is, anything can be made. In some technologies, very thin overhanging elements are provided with supports, thanks to which they can be avoided from sagging.
Naturally, this is a very simplified description of the stages of 3D printing, but they give a very clear idea of ​​the essence of the technique.

Other questions and answers about 3D printers and 3D printing:

  • Basics What is 3D scanning?
  • Basics What is a 3D model?

3D Printing Technologies

Different 3D printing technologies are used to reproduce different objects. They differ both in the consumables used, and in the speed and accuracy of printing. Here are the main 3D printing technologies:

  • Fused deposition modeling (FDM) . One of the most common 3D printing technologies, used in most desktop 3D printers, and represents an ideal price / quality ratio. Printing occurs by layer-by-layer supply of a thread of molten plastic;
  • Laser stereolithography (SLA) . The formation of the object occurs due to the layer-by-layer illumination of a liquid photopolymer resin by a laser, which hardens under the influence of radiation. One of the variations of this technology is DLP 3D printing. It uses a special projector instead of a laser. Both 3D printing methods are used to create objects with a high degree of detail. In the case of DLP printing, speed is also an added advantage;
  • Selective laser sintering (SLS) . Reproduction is performed by layer-by-layer melting of a special powder under the action of laser radiation. This 3D printing method is widely used in the industry for the manufacture of durable metal elements

3D Printing Applications

As you may have guessed by now, 3D printing is extremely versatile. The second name of the technology - rapid prototyping - speaks for itself. In the manufacture of prototypes and models of models, 3D printing can be simply indispensable. It is also a very cost-effective solution for small-scale production. In the aerospace and automotive industries, 3D technologies are already being used with might and main due to the high profitability and speed of manufacturing components. Culinary professionals are working on the development of 3D food printers, and in medicine, 3D printing has become something of a technology of the future. With the help of 3D bioprinting, it is planned to produce bones, organs and living tissues, but for now, implants and full-fledged medicines are printed on 3D printers. Desktop 3D printers can be used for domestic purposes: for repairs, making various household items, and so on. And designers, fashion designers, sculptors and artists appreciate the possibilities of 3D printing and 3D modeling as an unusual way to realize their talent.

Well, that was a brief description of what 3D printing is. We hope we were able to provide the necessary information in an accessible way. If you have additional questions that we have not covered, write to us by e-mail and we, if necessary, will add your questions! Best regards, 3DDevice team.

We also want to remind you about the possibility to order 3D printing, 3D scanning, 3D modeling services or purchase of related equipment and consumables with delivery throughout Ukraine in 3DDevice. If you have any questions, please contact us at one of the phone numbers listed here. We look forward to collaborating!

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3D printing for dummies or "what is a 3D printer?"

  • 1 3D printing term
  • 2 3D printing methods
    • 2.1 Extrusion printing
    • 2.2 Melting, sintering or gluing
    • 2.3 Stereolithography
    • 2.4 Lamination
  • 3 Fused Deposition Printing (FDM)
    • 3.1 Consumables
    • 3.2 Extruder
    • 3.3 Working platform
    • 3.4 Positioners
    • 3.5 Control
    • 3.6 Varieties of
      • FDM printers
  • 4 Laser stereolithography (SLA)
    • 4.1 Lasers and projectors
    • 4.2 Cuvette and resin
    • 4.3 Varieties of
      • Stereolithography Printers

The term 3D printing

The term 3D printing has several synonyms, one of which quite briefly and accurately characterizes the essence of the process - "additive manufacturing", that is, production by adding material. The term was not coined by chance, because this is the main difference between multiple 3D printing technologies and the usual methods of industrial production, which in turn received the name "subtractive technologies", that is, "subtractive". If during milling, grinding, cutting and other similar procedures, excess material is removed from the workpiece, then in the case of additive manufacturing, material is gradually added until a solid model is obtained.

Soon 3D printing will even be tested on the International Space Station

Strictly speaking, many traditional methods could be classified as "additive" in the broad sense of the word - for example, casting or riveting. However, it should be borne in mind that in these cases, either the consumption of materials is required for the manufacture of specific tools used in the production of specific parts (as in the case of casting), or the whole process is reduced to joining ready-made parts (welding, riveting, etc. ). In order for the technology to be classified as “3D printing”, the final product must be built from raw materials, not blanks, and the formation of objects must be arbitrary - that is, without the use of forms. The latter means that additive manufacturing requires a software component. Roughly speaking, additive manufacturing requires computer control so that the shape of final products can be determined by building digital models. It was this factor that delayed the widespread adoption of 3D printing until the moment when numerical control and 3D design became widely available and highly productive.

3D printing techniques

There are many 3D printing technologies, and even more names for them due to patent restrictions. However, you can try to divide technologies into main areas:

Extrusion printing

This includes techniques such as deposition fusion (FDM) and multi-jet printing (MJM). This method is based on the extrusion (extrusion) of consumables with the sequential formation of the finished product. As a rule, consumables consist of thermoplastics or composite materials based on them.

Melting, sintering or bonding

This approach is based on bonding powdered material together. Formation is done in different ways. The simplest is gluing, as is the case with 3D inkjet printing (3DP). Such printers deposit thin layers of powder onto the build platform, which are then selectively bonded with a binder. Powders can be made up of virtually any material that can be ground to a powder—plastic, wood, metal.

This model of James Bond's Aston Martin was successfully printed on a Voxeljet SLS printer and blown up just as successfully during the filming of Skyfall instead of the expensive original

sintering (SLS and DMLS) and smelting (SLM), which allow you to create all-metal parts. As with 3D inkjet printing, these devices apply thin layers of powder, but the material is not glued together, but sintered or melted using a laser. Laser sintering (SLS) is used to work with both plastic and metal powders, although metal pellets usually have a more fusible shell, and after printing they are additionally sintered in special ovens. DMLS is a variant of SLS installations with more powerful lasers that allow sintering metal powders directly without additives. SLM printers provide not just sintering of particles, but their complete melting, which allows you to create monolithic models that do not suffer from the relative fragility caused by the porosity of the structure. As a rule, printers for working with metal powders are equipped with vacuum working chambers, or they replace air with inert gases. Such a complication of the design is caused by the need to work with metals and alloys subject to oxidation - for example, with titanium.

Stereolithography

How an SLA printer works

Stereolithography printers use special liquid materials called "photopolymer resins". The term "photopolymerization" refers to the ability of a material to harden when exposed to light. As a rule, such materials react to ultraviolet irradiation.

Resin is poured into a special container with a movable platform, which is installed in a position near the surface of the liquid. The layer of resin covering the platform corresponds to one layer of the digital model. Then a thin layer of resin is processed by a laser beam, hardening at the points of contact. At the end of illumination, the platform together with the finished layer is immersed to the thickness of the next layer, and illumination is performed again.

Lamination

3D printers using lamination technology (LOM)

Some 3D printers build models using sheet materials - paper, foil, plastic film.

Layers of material are glued on top of each other and cut along the contours of the digital model using a laser or blade.

These machines are well suited for prototyping and can use very cheap consumables, including regular office paper. However, the complexity and noise of these printers, coupled with the limitations of the models they produce, limit their popularity.

Fused deposition modeling (FDM) and laser stereolithography (SLA) have become the most popular 3D printing methods used in the home and office.

Let's take a closer look at these technologies.

Fused Deposition Printing (FDM)

FDM is perhaps the simplest and most affordable 3D construction method, which is the reason for its high popularity.
High demand for FDM printers is driving device and consumable prices down rapidly, along with technology advances towards ease of use and improved reliability.

Consumables

ABS filament spool and finished model

FDM printers are designed to print with thermoplastics, which are usually supplied as thin filaments wound on spools. The range of "clean" plastics is very wide. One of the most popular materials is polylactide or "PLA plastic". This material is made from corn or sugar cane, which makes it non-toxic and environmentally friendly, but makes it relatively short-lived. ABS plastic, on the other hand, is very durable and wear-resistant, although it is susceptible to direct sunlight and can release small amounts of harmful fumes when heated. Many plastic items that we use on a daily basis are made from this material: housings for household appliances, plumbing fixtures, plastic cards, toys, etc.

In addition to PLA and ABS, printing is possible with nylon, polycarbonate, polyethylene and many other thermoplastics that are widely used in modern industry. More exotic materials are also possible, such as polyvinyl alcohol, known as "PVA plastic". This material dissolves in water, which makes it very useful for printing complex geometric patterns. But more on that below.

Model made from Laywoo-D3. Changing the extrusion temperature allows you to achieve different shades and simulate annual rings

It is not necessary to print with homogeneous plastics. It is also possible to use composite materials imitating wood, metals, stone. Such materials use all the same thermoplastics, but with impurities of non-plastic materials.

So, Laywoo-D3 consists partly of natural wood dust, which allows you to print "wooden" products, including furniture.

The material called BronzeFill is filled with real bronze, and models made from it can be ground and polished, achieving a high similarity to products made from pure bronze.

One has only to remember that thermoplastics serve as a connecting element in composite materials - they determine the thresholds of strength, thermal stability and other physical and chemical properties of finished models.

Extruder

Extruder - FDM print head. Strictly speaking, this is not entirely true, because the head consists of several parts, of which only the feed mechanism is directly "extruder". However, by tradition, the term "extruder" is commonly used as a synonym for the entire print assembly.

FDM extruder general design

The extruder is designed for melting and applying thermoplastic thread. The first component is the thread feed mechanism, which consists of rollers and gears driven by an electric motor. The mechanism feeds the thread into a special heated metal tube with a small diameter nozzle, called a "hot end" or simply a "nozzle". The same mechanism is used to remove the thread if a change of material is needed.

The hot end is used to heat and melt the thread fed by the puller. As a rule, nozzles are made from brass or aluminum, although more heat-resistant, but also more expensive materials can be used. For printing with the most popular plastics, a brass nozzle is quite enough. The “nozzle” itself is attached to the end of the tube with a threaded connection and can be replaced with a new one in case of wear or if a change in diameter is necessary. The nozzle diameter determines the thickness of the molten filament and, as a result, affects the print resolution. The heating of the hot end is controlled by a thermistor. Temperature control is very important, because when the material is overheated, pyrolysis can occur, that is, the decomposition of plastic, which contributes both to the loss of the properties of the material itself and to clogging of the nozzle.

PrintBox3D One FDM Extruder

To prevent the filament from melting too early, the top of the hot end is cooled by heatsinks and fans. This point is of great importance, since thermoplastics that pass the glass transition temperature significantly expand in volume and increase the friction of the material with the walls of the hot end. If the length of such a section is too long, the pulling mechanism may not have enough strength to push the thread.

The number of extruders may vary depending on the purpose of the 3D printer. The simplest options use a single print head. The dual extruder greatly expands the capabilities of the device, allowing you to print one model in two different colors, as well as using different materials. The last point is important when building complex models with overhanging structural elements: FDM printers cannot print “over the air”, since the applied layers require support. In the case of hinged elements, temporary support structures have to be printed, which are removed after printing is completed. The removal process is fraught with damage to the model itself and requires accuracy. In addition, if the model has a complex structure with internal cavities that are difficult to access, building conventional supports may not be practical due to the difficulty in removing excess material.

Finished model with PVA supports (white) before and after washing

In such cases, the very water-soluble polyvinyl alcohol (PVA) comes in handy. Using a dual extruder, you can build a model from waterproof thermoplastic using PVA to create supports.

After printing, PVA can be simply dissolved in water and a complex product of perfect quality can be obtained.

Some FDM printers can use three or even four extruders.

Work platform

Heated platform covered with removable glass work table

Models are built on a special platform, often equipped with heating elements. Preheating is required for a wide range of plastics, including the popular ABS, which are subject to a high degree of shrinkage when cooled. The rapid loss of volume by cold coats compared to freshly applied material can lead to model distortion or delamination. The heating of the platform makes it possible to significantly equalize the temperature gradient between the upper and lower layers.

Heating is not recommended for some materials. A typical example is PLA plastic, which requires a fairly long time to harden. Heating PLA can lead to deformation of the lower layers under the weight of the upper ones. When working with PLA, measures are usually taken not to heat up, but to cool the model. Such printers have characteristic open cases and additional fans blowing fresh layers of the model.

Calibration screw for work platform covered with blue masking tape

The platform needs to be calibrated before printing to ensure that the nozzle does not hit the applied layers and move too far causing air-to-air printing resulting in plastic vermicelli. The calibration process can be either manual or automatic. In manual mode, calibration is performed by positioning the nozzle at different points on the platform and adjusting the platform inclination using the support screws to achieve the optimal distance between the surface and the nozzle.

As a rule, platforms are equipped with an additional element - a removable table. This design simplifies the cleaning of the working surface and facilitates the removal of the finished model. Stages are made from various materials, including aluminum, acrylic, glass, etc. The choice of material for the manufacture of the stage depends on the presence of heating and consumables for which the printer is optimized.

For a better adhesion of the first layer of the model to the surface of the table, additional tools are often used, including polyimide film, glue and even hairspray! But the most popular tool is inexpensive, but effective masking tape. Some manufacturers make perforated tables that hold the model well but are difficult to clean. In general, the expediency of applying additional funds to the table depends on the consumable material and the material of the table itself.

Positioning mechanisms

Operation of positioning mechanisms

Of course, the print head must move relative to the working platform, and unlike conventional office printers, positioning must be done not in two, but in three planes, including height adjustment.

Positioning pattern may vary. The simplest and most common option involves mounting the print head on perpendicular guides driven by stepper motors and providing positioning along the X and Y axes.

Vertical positioning is carried out by moving the working platform.

On the other hand, it is possible to move the extruder in one plane and the platforms in two.

SeemeCNC ORION Delta Printer

One option that is gaining popularity is the delta coordinate system.

Such devices are called "delta robots" in the industry.

In delta printers, the print head is suspended on three manipulators, each of which moves along a vertical rail.

The synchronous symmetrical movement of the manipulators allows you to change the height of the extruder above the platform, and the asymmetric movement causes the head to move in the horizontal plane.

A variant of this system is the reverse delta design, where the extruder is fixed to the ceiling of the working chamber, and the platform moves on three support arms.

Delta printers have a cylindrical build area, and their design makes it easy to increase the height of the working area with minimal design changes by extending the rails.

In the end, everything depends on the decision of the designers, but the fundamental principle does not change.

Control

Typical Arduino-based controller with add-on modules

FDM printer operation, including nozzle and platform temperature, filament feed rate, and stepper motors for positioning the extruder, is controlled by fairly simple electronic controllers. Most controllers are based on the Arduino platform, which has an open architecture.

The programming language used by printers is called G-code (G-Code) and consists of a list of commands executed in turn by the 3D printer systems. G-code is compiled by programs called "slicers" - standard 3D printer software that combines some of the features of graphics editors with the ability to set print options through a graphical interface. The choice of slicer depends on the printer model. RepRap printers use open source slicers such as Skeinforge, Replicator G and Repetier-Host. Some companies make printers that require proprietary software.

Program code for printing is generated using slicers

As an example, we can mention Cube printers from 3D Systems. There are companies that offer proprietary software but allow third-party software, as is the case with the latest generation of MakerBot 3D printers.

Slicers are not intended for 3D design per se. This task is done with CAD editors and requires some 3D design skills. Although beginners should not despair: digital models of a wide variety of designs are offered on many sites, often even for free. Finally, some companies and individuals offer 3D design services for custom printing.

Finally, 3D printers can be used in conjunction with 3D scanners to automate the process of digitizing objects. Many of these devices are designed specifically to work with 3D printers. Notable examples include the 3D Systems Sense handheld scanner and the MakerBot Digitizer handheld desktop scanner.

MakerBot Replicator 5th Generation FDM Printer with built-in control module on the top of the frame

The user interface of a 3D printer can consist of a simple USB port for connecting to a personal computer. In such cases, the device is actually controlled by the slicer.

The disadvantage of this simplification is a rather high probability of printing failure when the computer freezes or slows down.

A more advanced option includes an internal memory or memory card interface to make the process standalone.

These models are equipped with control modules that allow you to adjust many print parameters (such as print speed or extrusion temperature). The module may include a small LCD display or even a mini-tablet.

Varieties of FDM printers

Stratasys Fortus 360mc professional FDM printer that allows printing with nylon

FDM printers are very, very diverse, ranging from the simplest home-made RepRap printers to industrial installations capable of printing large-sized objects.

Stratasys, founded by Scott Crump, the inventor of FDM technology, is a leader in the production of industrial installations.

You can build the simplest FDM printers yourself. Such devices are called RepRap, where "Rep" indicates the possibility of "replication", that is, self-reproduction.

RepRap printers can be used to print custom made plastic parts.

Controller, rails, belts, motors and other components can be easily purchased separately.

Of course, assembling such a device on your own requires serious technical and even engineering skills.

Some manufacturers make it easy by selling DIY kits, but these kits still require a good understanding of the technology.

A variant of the popular late 3rd generation Prusa RepRap printer

If you like to make things with your own hands, then RepRap printers will pleasantly please you with the price: the average cost of the popular early generation Prusa Mendel design is about $500 in a complete set.

And, despite their "do-it-yourself nature", RepRap printers are quite capable of producing models with quality at the level of expensive branded counterparts.

Ordinary users who do not want to delve into the intricacies of the process, but require only a convenient device for household use, can purchase a ready-made FDM printer.

Many companies are focusing on the development of the consumer market segment, offering 3D printers for sale that are ready to print "straight out of the box" and do not require serious computer skills.

3D Systems Cube consumer 3D printer

The most famous example of a consumer 3D printer is the 3D Systems Cube.

While it doesn't boast a huge build area, ultra-fast print speeds, or superb build quality, it's easy to use, affordable, and safe: This printer has received the necessary certification to be used even by children.

Mankati FDM printer demonstration: http://youtu. be/51rypJIK4y0

Laser Stereolithography (SLA)

Stereolithographic 3D printers are widely used in dental prosthetics

Stereolithographic printers are the second most popular and widespread after FDM printers.

These units deliver exceptional print quality.

The resolution of some SLA printers is measured in a matter of microns - it is not surprising that these devices quickly won the love of jewelers and dentists.

The software side of laser stereolithography is almost identical to FDM printing, so we will not repeat ourselves and will only touch on the distinctive features of the technology.

Lasers and projectors

Projector illumination of a photopolymer model using the Kudo3D Titan DLP printer as an example

The cost of stereolithography printers is rapidly declining, due to growing competition due to high demand and the use of new technologies that reduce the cost of construction.

Although the technology is generically referred to as "laser" stereolithography, most recent developments use UV LED projectors for the most part.

Projectors are cheaper and more reliable than lasers, do not require the use of delicate mirrors to deflect the laser beam, and have higher performance. The latter is explained by the fact that the contour of the whole layer is illuminated as a whole, and not sequentially, point by point, as is the case with laser options. This variant of the technology is called projection stereolithography, "DLP-SLA" or simply "DLP". However, both options are currently common - both laser and projector versions.

Cuvette and resin

Photopolymer resin is poured into a cuvette

A photopolymer resin that looks like epoxy is used as consumables for stereolithographic printers. Resins can have a variety of characteristics, but they all share one key feature for 3D printing applications: these materials harden when exposed to ultraviolet light. Hence, in fact, the name "photopolymer".

When polymerized, resins can have a wide variety of physical characteristics. Some resins are like rubber, others are hard plastics like ABS. You can choose different colors and degrees of transparency. The main disadvantage of resins and SLA printing in general is the cost of consumables, which significantly exceeds the cost of thermoplastics.

On the other hand, stereolithography printers are mainly used by jewelers and dentists who do not need to build large parts but appreciate the savings from fast and accurate prototyping. Thus, SLA printers and consumables pay for themselves very quickly.

An example of a model printed on a 3D laser stereolithography printer

Resin is poured into a cuvette, which can be equipped with a lowering platform. In this case, the printer uses a leveling device to flatten the thin layer of resin covering the platform just prior to irradiation. As the model is being made, the platform, together with the finished layers, is “embedded” in the resin. Upon completion of printing, the model is removed from the cuvette, treated with a special solution to remove liquid resin residues and placed in an ultraviolet oven, where the final illumination of the model is performed.

Some SLA and DLP printers work in an "inverted" scheme: the model is not immersed in the consumable, but "pulled" out of it, while the laser or projector is placed under the cuvette, and not above it. This approach eliminates the need to level the surface after each exposure, but requires the use of a cuvette made of a material transparent to ultraviolet light, such as quartz glass.

The accuracy of stereolithographic printers is extremely high. For comparison, the standard for vertical resolution for FDM printers is considered to be 100 microns, and some variants of SLA printers allow you to apply layers as thin as 15 microns. But this is not the limit. The problem, rather, is not so much in the accuracy of lasers, but in the speed of the process: the higher the resolution, the lower the print speed. The use of digital projectors allows you to significantly speed up the process, because each layer is illuminated entirely. As a result, some DLP printer manufacturers claim to be able to print with a vertical resolution of one micron!

Video from CES 2013 showing Formlabs Form1 stereolithography 3D printer in action: http://youtu.be/IjaUasw64VE

Stereolithography Printer Options

Formlabs Form1 Desktop Stereolithography Printer

As with FDM printers, SLA printers come in a wide range in terms of size, features and cost. Professional installations can cost tens if not hundreds of thousands of dollars and weigh a couple of tons, but the rapid development of desktop SLA and DLP printers is gradually reducing the cost of equipment without compromising print quality.

Models such as the Titan 1 promise to make stereolithographic 3D printing affordable for small businesses and even home use at prices in the region of $1,000.

Learn more