What Is 3D Printing?- Types And How Does its Work

What is 3D Printing?

3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a 3D digital model.

The term “3D printing” can refer to a variety of processes in which material is deposited, joined, or solidified under computer control into a three-dimensional object, where the materials, such as plastics, liquids, or powder grains, are fused together, typically layer by layer.

In the 1980s, 3D printing techniques were only considered suitable for producing functional or aesthetic prototypes, a more appropriate term for this at the time was rapid prototyping.

Since 2019, the precision, repeatability, and material diversity of 3D printing have increased to the point that some 3D printing processes are considered industrial-grade production technologies, with the term additive manufacturing being used interchangeably with 3D printing.

One of the main benefits of 3D printing is the ability to produce very complex shapes or geometries that would otherwise be impossible to design by hand, including hollow parts or parts with internal truss structures to reduce weight. Fused Deposition Modeling (FDM), which uses a continuous filament of thermoplastic material, is the most commonly used 3D printing process as of 2020.

Related Article: What is Additive Manufacturing?

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.

How Does A 3d Printer Work?

A 3D printer essentially works by extruding molten plastic through a tiny nozzle that it moves around precisely under computer control. It prints one layer, waits for it to dry, and then prints the next layer on top. The plastic from which models are printed is obviously hugely important.

3D printing is part of the additive manufacturing family and uses similar methods to a traditional inkjet printer- albeit in 3D. It takes a combination of top-of-the-line software, powder-like materials, and precision tools to create a three-dimensional object from scratch. Below are a few of the main steps 3D printers take to bring ideas to life.

3D Modeling Software

The first step of any 3D printing process is 3D modeling. To maximize precision (and because 3D printers can’t magically guess what you want to print), all objects have to be designed in 3D modeling software. Some designs are too intricate and detailed for traditional manufacturing methods.

That’s where this CAD software comes in. Modeling allows printers to customize their product down to the tiniest detail. The 3D modeling software’s ability to allow for precision designs is why 3D printing is being hailed as a true game-changer in many industries.

This modeling software is especially important to an industry, like dentistry, where labs are using three-dimensional software to design teeth aligners that precisely fit the individual. It’s also vital to the space industry, where they use the software to design some of the most intricate parts of a Rocketship.

Slicing the Model

Once a model is created, it’s time to “slice” it. Since 3D printers cannot conceptualize the concept of three dimensions, like humans, engineers need to slice the model into layers in order for the printer to create the final product.

Slicing software takes scans of each layer of a model and will tell the printer how to move in order to recreate that layer. Slicers also tell 3D printers were to “fill” a model.

This fill gives a 3D printed object internal lattices and columns that help shape and strengthen the object. Once the model is sliced, it’s sent off to the 3D printer for the actual printing process.

The 3D Printing Process

When the modeling and slicing of a 3D object is completed, it’s time for the 3D printer to finally take over. The printer acts generally the same as a traditional inkjet printer in the direct 3D printing process, where a nozzle moves back and forth while dispensing a wax or plastic-like polymer layer-by-layer, waiting for that layer to dry, then adding the next level. It essentially adds hundreds or thousands of 2D prints on top of one another to make a three-dimensional object.

3D Printing Materials

There are a variety of different materials that a printer uses in order to recreate an object to the best of its abilities. Here are some examples:

• Acrylonitrile butadiene styrene (ABS): Plastic material that is easy to shape and tough to break. The same material that LEGOs are made out of.
• Carbon Fiber Filaments: Carbon fiber is used to create objects that need to be strong, but also extremely lightweight.
• Conductive Filaments: These printable materials are still in the experimental stage and can be used for printing electric circuits without the need for wires. This is a useful material for wearable technology.
• Flexible Filaments: Flexible filaments produce prints that are bendable, yet tough. These materials can be used to print anything from wristwatches to phone covers.
• Metal Filament: Metal filaments are made of finely ground metals and polymer glue. They can come in steel, brass, bronze and copper in order to get the true look and feel of a metal object.
• Wood Filament: These filaments contain finely ground wood powder mixed with polymer glue. These are obviously used to print wooden-looking objects and can look like a lighter or darker wood depending on the temperature of the printer.

The 3D printing process takes anywhere from a few hours for really simple prints, like a box or a ball, to weeks for much larger detailed projects, like a full-sized home.

Examples of 3D Printing

3D printing encompasses many types of technologies and materials, as 3D printing is used in almost every imaginable industry. It’s important to think of it as a cluster of different industries with a variety of different uses.

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 artifacts
• Reconstructing evidence in forensic pathology
• Movie props

Types of 3D Printing Technologies

There are several types of 3D printing, which include:

• Stereolithography (SLA)
• Selective Laser Sintering (SLS)
• Fused Deposition Modeling (FDM)
• Digital Light Process (DLP)
• Multi Jet Fusion (MJF)
• PolyJet.
• Direct Metal Laser Sintering (DMLS)
• Electron Beam Melting (EBM)

1. Polymer 3D Printing Processes

Let’s outline some common 3D printing processes for plastics and discuss when each is of the greatest benefit for product developers, engineers, and designers.

2. Stereolithography (SLA)

Stereolithography (SLA) is the original industrial 3D printing process. SLA printers are characterized by producing parts with a high level of detail, smooth surfaces, and tight tolerances. The high-quality surfaces of SLA parts not only look good but can also support the part’s function, for example, testing the fit of an assembly.

It is widely used in the medical industry. Common applications include anatomical models and microfluidics. We use Vipers, ProJets, and iPros 3D printers from 3D Systems for SLA parts.

3. Selective Laser Sintering (SLS)

Selective laser sintering (SLS) melts nylon-based powders into solid plastic. Since SLS parts are made of real thermoplastic material, they are durable, suitable for functional tests, and can carry living hinges and snaps.

Compared to SL, parts are stronger but have rougher surfaces. SLS does not require support structures, so the entire build platform can be used to nest multiple parts in a single build. This makes it suitable for parts quantities that are higher than with other 3D printing processes. Many SLS parts are used to prototype designs that will one day be injection molded. For our SLS printers we use sPro140 machines developed by 3D systems.

4. PolyJet

PolyJet is another plastic 3D printing process, but there is a twist. It can make parts with multiple properties like colors and materials. Designers can use the technology to prototype elastomeric or over-molded parts. If your design is made from a single, rigid plastic, we recommend sticking with SL or SLS, this is more economical.

However, when you’re prototyping an overmold or silicone rubber design, PolyJet can save you from the need to invest in tooling early in the development cycle. This can help you iterate and validate your design faster and save you money.

5. Digital Light Processing (DLP)

Digital light processing is similar to SLA in that it cures liquid resin with light. The main difference between the two technologies is that DLP uses a digital light projection screen while SLA uses a UV laser.

This means that DLP 3D printers can map an entire layer of the build at once, resulting in faster build speeds. Although DLP printing is often used for rapid prototyping, its higher throughput makes it suitable for the production of plastic parts in small numbers.

6. Multi Jet Fusion (MJF)

Similar to SLS, Multi Jet Fusion also builds functional parts from nylon powder. Instead of sintering the powder with a laser, MJF uses an inkjet array to apply flux to the bed of nylon powder. Then a heating element goes over the bed to fuse each layer.

This leads to more uniform mechanical properties compared to SLS and to improved surface quality. Another benefit of the MJF process is the accelerated build time, which leads to lower production costs.

7. Fused Deposition Modeling (FDM)

Fused Deposition Modeling (FDM) is a popular desktop 3D printing technology for plastic parts. An FDM printer extrudes a plastic filament layer by layer onto the build platform. This is an inexpensive and quick way to create physical models.

There are some cases where FDM can be used for functional testing, but the technology is limited due to parts with relatively rough surfaces and a lack of strength.

8. Direct Metal Laser Sintering (DMLS)

Metal 3D printing opens up new possibilities for the construction of metal parts. The process we use at Protolabs to 3D print metal parts is direct metal laser sintering (DMLS). It is widely used to reduce multi-piece metal assemblies to a single component or too lightweight parts with internal channels or hollowed-out features.

DMLS is suitable for both prototyping and production because parts are as dense as those made using traditional metal manufacturing methods such as machining or casting. By creating metal components with complex geometries, it is also suitable for medical applications where a part design must mimic an organic structure.

9. Electron Beam Melting (EBM)

Electron beam melting is another metal 3D printing technology that uses an electron beam controlled by electromagnetic coils to melt the metal powder. The print bed is heated under vacuum conditions during the build-up. The temperature to which the material is heated is determined by the material used.

How Do You Use A 3D Printer? (Step by Step)

Many different technologies share the same basic steps which we’ll cover next, but each 3D printer can also be easier or harder to use depending on its features.

Step 1 – Prepare your design for 3D printing

By this point, it’s important you have a part ready to print and you have chosen your material. This part can be one you designed yourself using CAD (computer-aided design), one taken from a 3D scan, or one you have taken from an inventory of existing designs.

Before you start printing, you need to translate your design into ‘coordinates’ the 3D printer can understand, as well as tell it important parameters such as the material you are printing with.

This is known as ‘slicing’, because it involves slicing the 3D design into you guessed it layers. This is typically done in a program known as slicing or print preparation software.

Step 2 – Set up your printer

You could also do this step first if you like. Or you may not need to at all, for example, if you regularly print the same type of parts.

But before you start printing, be sure to check you have the right material loaded. Also choose different nozzle sizes, with a smaller nozzle giving more detailed prints and a larger nozzle faster print time.

Step 3 – Send your file to the printer

Once you are ready to go, you need to get the file to your 3D printer. There are two main ways to do this. One is to load the file onto a data storage device (such as a USB drive), put it in the printer, and start your print job via the printer’s interface.

The other option is to send the job remotely to a network-enabled printer via your local network or the cloud. Remote printing is particularly helpful if you are not in the same location as your 3D printer.

Step 4 – 3D print

Now you can sit back and relax! Or if you’re at work, get on with something else while the printer does its job.

Printing times vary depending on the size and detail level of your printed object and your 3D printer type. A small component or rough prototype may only take a few hours. Most parts will be ready the next day if you leave the printer running overnight. And if you need a very large, detailed print, you may have to wait a couple of days.

What is 3D Printing Used For?

3D printing can be used both recreationally and professionally, across various industries. It has applications in many different fields and sectors, from the healthcare industry to engineering, and even fashion.

Increasingly, 3D printing is seen as a sustainable and cost-friendly solution for creating prototypes and tools for different manufacturing projects and processes. Traditionally, acquiring prototypes can be time-consuming and costly, requiring companies to depend on outside manufacturers. 3D printing allows companies to quickly make units of an object, tool, or prototype, all in-house.

A great example of this is the shoe company Camper. In-house 3D printing has allowed them to transform their nearly month and a half long modeling and designing process into an operation that takes only several days.

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