3D Printing: Definition, 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 digital 3D model. The term “3D printing” can refer to a variety of processes in which material is deposited, joined, or solidified under computer control to create a three-dimensional object, with the material being added together layer by layer.

A 3D printed object is created 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 viewed as a thinly sliced cross-section of the object.

3D printing is the opposite of subtractive manufacturing, in which a piece of metal or plastic is cut out/hollowed out with a milling machine, for example.

3D printing allows you to create complex shapes with less material than traditional manufacturing methods.

Check out our Detail 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.

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

How Does 3D Printing Work?

3D printing belongs to the additive manufacturing family and uses methods similar to a conventional inkjet printer – but in 3D. It takes a combination of world-class software, powdery materials, and precision tools to create a three-dimensional object from scratch. Below are some of the key steps 3D printers take to bring ideas to life.

3D Modeling Software

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

This is where this CAD software comes in. With modeling, printers can customize their product down to the smallest detail. The ability of 3D modeling software to enable precise designs is the reason why 3D printing is hailed as a real game-changer in many industries.

This modeling software is especially important in an industry like dentistry, where laboratories use three-dimensional software to design tooth aligners that are precisely tailored to the individual. This is also vital to the aerospace industry, where they use software to design some of the most intricate parts of a rocketship.

Slicing the Model

Once a model has been created, it’s time to cut it into slices. Because 3D printers cannot conceive the concept of three-dimensional data like humans do, engineers need to break down the model into layers so that the printer can create the final product.

The slicing software scans each layer of a model and tells the printer how to move to recreate that layer. Slicers also tell 3D printers were to “fill” a model. This fill creates internal grids and crevices of a 3D printed object that can be used to shape and reinforce the object. Once the model is sliced, it is sent to the 3D printer for the actual printing process.

The 3D Printing Process

When the modeling and slicing of a 3D object is done, the 3D printer must finally take control. The printer generally behaves the same as a traditional inkjet printer in direct 3D printing, where a nozzle moves back and forth while a wax or plastic-like polymer is dispensed layer by layer until that layer dries, adding the next layer.

Essentially hundreds or thousands of 2D prints are added on top of each other to create a three-dimensional object. There are a variety of different materials that a printer uses to recreate an object to the best of his ability. Here are some examples:

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

The 3D printing process takes from a few hours for really simple prints like a box or ball to weeks for much more detailed projects like a full-size house.

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

Rapid Prototyping & Rapid Manufacturing

Companies have been using 3D printers in their design process to create prototypes since the late 1970s. Using 3D printers for these purposes is known as rapid prototyping.

Why use 3D Printers for Rapid Prototyping?

In short, it’s quick and relatively cheap. From the idea to the 3D model to holding a prototype in your hands, it’s a matter of days instead of weeks. Iterations are easier and cheaper to do, and you don’t need expensive molds or tools.

In addition to rapid prototyping, 3D printing is also used for rapid manufacturing. Rapid manufacturing is a new manufacturing method in which companies use 3D printers for custom manufacturing in small runs batches.

Check out our Detail article: What is Rapid Prototyping?

Types of 3D Printing Technologies and Processes

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 overmolded 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 lack of strength.

Metal 3D Printing Processes

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 to 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.

3D Printing Industries

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

  • Aerospace. 3D printing is used across the aerospace (and aerospace) industry due to the ability to create light, yet geometrically complex parts, such as blisks. Rather than building apart from several components, 3D printing allows for an item to be created as one whole component, reducing lead times and material wastage.
  • Automotive. The automotive industry has embraced 3D printing due to the inherent weight and cost reductions. It also allows for rapid prototyping of new or bespoke parts for a test or small-scale manufacture. So, for example, if a particular part is no longer available, it can be produced as part of a small, bespoke run. Alternatively, items or fixtures can be printed overnight and are ready for testing ahead of a larger manufacturing run.
  • Medical. The medical sector has found uses for 3D printing in the creation of made-to-measure implants and devices. For example, hearing aids can be created quickly from a digital file that is matched to a scan of the patient’s body. 3D printing can also dramatically reduce costs and production times.
  • Rail. The rail industry has found a number of applications for 3D printing, including the creation of customized parts, such as armrests for drivers and housing covers for train couplings. Bespoke parts are just one application for the rail industry, which has also used the process to repair worn rails.
  • Robotics. The speed of manufacture, design freedom, and ease of design customization make 3D printing perfectly suited to the robotics industry. This includes work to create bespoke exoskeletons and agile robots with improved agility and efficiency.

Application of 3D Printing

  • Shortening of a new production line implementation time with the use of 3D printing.
  • Evaluation of ergonomics, dimensions, and accuracy of a prototype
  • The element of a production tooling
  • Verification of the correctness of the prototype execution
  • Testing of tooling design
  • Mock-ups of industrial machines
  • Designing and construction of racing cars
  • Test of mecanum wheels mounted in a robot
  • Complex geometry dies
  • Drone housing

What are the Advantages and Disadvantages of 3D Printing?

What are the Pros of 3D Printing?

This production process offers a range of advantages compared to traditional manufacturing methods. These advantages include those related to design, time and cost, amongst others.

1. Flexible Design

3D printing allows more complex designs to be designed and printed than traditional manufacturing methods. More traditional processes have design limitations that no longer apply when using 3D printing.

2. Rapid Prototyping

With 3D printing, parts can be made in hours, which speeds up the prototyping process. This allows each phase to be completed more quickly. Compared to editing prototypes, 3D printing is cheaper and faster to create parts because the part can be completed in hours, so any design change can be made much more efficiently.

3. Print on Demand

Print on demand is another advantage because, in contrast to conventional manufacturing processes, not much space is required for storage. This saves space and money as there is no need to print in bulk unless necessary.

The 3D design files are all stored in a virtual library while being printed with a 3D model as a CAD or STL file. This means that they can be found and printed if necessary. Changes to designs can be made at very low cost by editing individual files without wasting outdated inventory and investing in tools.

4. Strong and Lightweight Parts

The main 3D printing material used is plastic, although some metals can also be used for 3D printing. However, plastics offer advantages because they are lighter than their metal equivalents. This is especially important in industries such as the automotive and aerospace industries, where lightweight is an issue and can result in higher fuel efficiency.

In addition, parts can be made from tailor-made materials to provide certain properties such as heat resistance, higher strength or water repellency.

5. Fast Design and Production

Depending on the design and complexity of a part, 3D printing can print objects in hours. This is much faster than with molded or machined parts. Not only can 3D printing save time making the part, but the design process can also be very fast by creating STL or CAD files ready to be printed.

6. Minimising Waste

Making parts only requires the materials needed to make the part itself, with little or no waste compared to alternative methods that are cut from large pieces of non-recyclable materials. The process not only saves resources, it also reduces the cost of the materials used.

7. Cost Effective

As a one-step manufacturing process, 3D printing saves time and therefore costs associated with the use of different machines for production. 3D printers can also be set up and released for work so that operators don’t have to be present all the time.

8. Ease of Access

3D printers are becoming more accessible as more local service providers offer outsourcing services for manufacturing work. This saves time and does not require expensive transportation costs compared to more traditional manufacturing methods made overseas in countries like China.

9. Environmentally Friendly

Because this technology reduces the amount of material wasted, this process is inherently environmentally friendly. However, the environmental benefits expand when you factor in factors such as improved fuel efficiency through the use of lightweight 3D printed parts.

10. Advanced Healthcare

In the medical field, 3D printing is used to save lives by printing organs for the human body such as livers, kidneys, and hearts. Further advances and applications in the health sector are evolving to make some of the greatest advances in the use of the technology.

What are the Cons of 3D Printing?

Like with almost any other process there are also drawbacks of 3D printing technology which should be considered before opting to use this process.

1. Limited Materials

While 3D printing can create elements from a range of plastics and metals, the range of raw materials available is not exhaustive. This is due to the fact that not all metals or plastics can be temperature controlled in such a way that 3D printing is possible. In addition, many of these printable materials cannot be recycled and very few are food safe.

2. Restricted Build Size

3D printers currently have small pressure chambers that limit the size of the parts to be printed. Anything larger must be printed in separate pieces and put together after production. This can add cost and time to larger parts because the printer must print more parts before hand-fitting the parts together.

3. Post Processing

Although large parts require post-processing as noted above, most 3D printed parts require cleaning to remove the substrate from the build and smooth the surface to achieve the required finish. Post-processing methods used include water jetting, grinding, chemical soaking and rinsing air or heat drying, assembly, and others.

The amount of post-processing required depends on factors including the size of the part being manufactured, the intended application, and the type of 3D printing technology used to produce it. While 3D printing enables parts to be produced quickly, post-processing can slow down manufacturing speed.

4. Large Volumes

3D printing is a static cost as opposed to traditional techniques like injection molding, which can be more cost-effective to manufacture in large quantities. While the initial investment for 3D printing can be lower than for other manufacturing processes, once it is scaled up to large quantities for mass production, the unit cost does not decrease as injection molding does.

5. Part Structure

In 3D printing (also known as additive manufacturing), parts are made layer by layer. Although these layers adhere to one another, it also means that under certain stresses or orientations they can delaminate.

This problem is of greater concern when making articles using Fused Deposition Modeling (FDM), while Polyjet and Multijet parts are also more brittle. In certain cases it may be better to use injection molding as this creates homogeneous parts that will not separate and break.

6. Reduction in Manufacturing Jobs

Another disadvantage of 3D technology is the potential reduction in human labor, as most of the production is automated and done by printers. However, many developing world countries rely on low-skilled jobs to keep their economies going, and this technology could jeopardize those manufacturing orders by reducing the need for overseas manufacturing.

7. Design Inaccuracies

Another potential problem with 3D printing is directly related to the type of machine or process used. Some printers have tighter tolerances, which means the final parts may differ from the original design. This can be remedied in post-processing, but it must be taken into account that this further increases the time and production costs.

8. Copyright Issues

As 3D printing becomes more popular and accessible, there will be greater opportunities for people to make counterfeit and counterfeit products and it will be almost impossible to tell the difference. This has obvious copyright related issues as well as quality control issues.

FAQs.

What is 3D printing?

3D printing or additive manufacturing is the 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.

How Does 3D Printing Work?

In short, 3D printers use computer-aided design (CAD) to create 3D objects from a variety of materials, like molten plastic or powders. They work from the ground up and pile on layer after layer until the object looks exactly like it was envisioned. These printers have extreme flexibility in what can be printed.

What are the types of 3D Printing?

There are several types of 3D printing:
1. Stereolithography (SLA)
2. Selective Laser Sintering (SLS)
3. Fused Deposition Modeling (FDM)
4. Digital Light Process (DLP)
5. Multi Jet Fusion (MJF)
6. PolyJet.
7. Direct Metal Laser Sintering (DMLS)
8. Electron Beam Melting (EBM)