WHAT IS 3D PRINTING? - DEFINITION AND TYPES OF TECHNOLOGY
3D printing, also known as additive manufacturing, is a method of creating a three-dimensional object in layers using a computer-generated design.
3D printing is an additive process in which layers of material are built up to create a 3D part. This is the opposite of subtractive manufacturing, in which the final design is cut from a larger block of material. As a result, 3D printing generates less material waste.
3D printing is also great for creating complex custom pieces, making it ideal for rapid prototyping .
- What materials can be used?
- Story
- Technologies
- Process types
- How long does it take?
- Advantages and disadvantages
- What is an STL file?
- Industries
- Services
- FAQ
What materials can be used in 3D printing?
There are many materials available for 3D printing, including thermoplastics such as acrylonitrile butadiene styrene (ABS) , metals (including powders) , resins , and ceramics.
History of 3D printing
Who Invented 3D Printing?
The earliest 3D printing hardware was developed by Hideo Kodama of the Nagoya Municipal Industrial Research Institute when he invented two additive methods for making 3D models.
When was 3D printing invented?
Based on Ralph Baker's decorative work (patent US423647A) in the 1920s, Hideo Kodama completed early work in 1981 on rapid prototyping with laser-cured resin. His invention was expanded over the next three decades, with the advent of stereolithography in 1984. Chuck Hull of 3D Systems invented the first 3D printer in 1987, which used the stereolithography process. It was followed by developments such as selective laser sintering and selective laser melting, among others. In the 1990s and 2000s, other costly 3D printing systems were developed, although their cost dropped dramatically after the patents expired in 2009, opening up the technology to more users.
3D printing technologies
There are three main types of 3D printing technologies: sintering, melting, and stereolithography.
Sintering is a technique in which a material is heated, but not to the point of melting, to create high resolution products. Metal powder is used for direct laser sintering of metals, and thermoplastic powders for selective laser sintering.
Meltdown 3D printing techniques include powder bed melting, electron beam melting, and direct energy deposition. Objects are printed using lasers, electric arcs, or electron beams that melt materials at high temperatures.
Stereolithography uses photopolymerization to create details. This technology uses the right light source to selectively interact with the material to cure and solidify the cross section of the object in thin layers.
3D printing processes
Types of 3D printing
3D printing processes, also known as additive manufacturing, have been classified into seven groups according to ISO/ASTM 52900 Additive manufacturing - general principles - terminology. All types of 3D printing fall into one of the following types:
- Jet application of binder
- Direct thermal application
- material extrusion
- Material blasting
- Fusion of the powder layer
- Sheet lamination
- PHOTO Polymerization of materials
Jet application of binder
Binder blasting applies a thin layer of powdered material, such as metal, polymer sand, or ceramic, to the platform , after which the print head applies drops of adhesive to hold the particles together. In this way, the part is formed layer by layer, and after that, post-processing may be required to complete the assembly. As examples of post-processing, metal parts can be thermally sintered or impregnated with a low melting point metal such as bronze, and full-color resin or ceramic parts can be impregnated with cyanoacrylate adhesive.
Inkjet bonding can be used in a variety of applications, including metal 3D printing, full color prototypes, and large-scale ceramic molds.
Direct thermal application
Direct thermal deposition uses focused thermal energy such as an electric arc, laser, or electron beam to fuse a wire or powder raw material during the deposition process. The process runs horizontally to create a layer, and the layers are stacked vertically to create a part.
This process can be used with a variety of materials including metals, ceramics and polymers.
Material extrusion
Material extrusion or Fused Deposition Modeling (FDM) uses a spool of filament that is fed into an extrusion head with a heated nozzle. The extrusion head heats, softens and deposits the heated material in predetermined locations where it cools to create a layer of material, after which the build platform moves down for the next layer.
This process is cost-effective and has short manufacturing times, but has low dimensional accuracy and often requires post-processing to create a smooth surface. This process also tends to create anisotropic parts, which means they are weaker in one direction and therefore not suitable for critical applications.
Material blasting
Inkjet material processing works similarly to inkjet printing, only instead of applying ink to a page, this process applies layers of liquid material using one or more printheads. The layers are then cured, after which the process starts all over again for the next layer. Blasting the material requires the use of support structures, but these can be made from a water-soluble material that can be washed off after the process is completed.
A precise process, material inkjet is one of the most expensive 3D printing methods, and parts tend to be brittle and break down over time. However, this process allows you to create full-color parts from a variety of materials.
Fusion of the powder layer
Powder bed fusion (PBF) is a process in which thermal energy (such as a laser or electron beam) selectively fuses portions of a powder layer to form a layer, and the layers are layered on top of each other to create a part. It should be noted that PBF covers both sintering and melting processes. The basic method of operation of all powder bed systems is the same: a blade or roller applies a thin layer of powder to the build platform, then the surface of the powder bed is scanned by a heat source that selectively heats the particles to bind them together. After a layer or cross section has been scanned by the heat source, the platform moves down to start the process from the next layer. The end result is a volume containing one or more fused parts surrounded by unaffected powder. When assembly is complete, the platform is fully raised to allow parts to be removed from unaffected powder and any necessary post-processing to begin.
Selective laser sintering (SLS) is often used for the manufacture of polymer parts and is well suited for prototypes or functional parts due to the obtained properties, and the absence of support structures (a layer of powder acts as a support) allows you to create parts with complex geometries. The resulting parts may have a grainy surface and internal porosity, which means the need for post-treatment.
Direct metal laser sintering (DMLS), selective laser melting (SLM), and electron beam powder bed fusion (EBPBF) are similar to SLS, except that these processes create parts from metal using a laser to layer-by-layer powder particles. Whereas SLM completely melts metal particles, DMLS only heats them up to their melting point, causing them to bond at the molecular level. Both SLM and DMLS require support structures due to the high heat input required in the process. These support structures are then removed in post-processing, either manually or by CNC. Finally, parts can be heat treated to relieve residual stresses.
Both DMLS and SLM produce parts with excellent physical properties—often stronger than conventional metal and with good surface finishes. They can be used to machine metal superalloys and sometimes ceramics that are difficult to machine in other ways. However, these processes can be expensive and the size of the resulting parts is limited by the size of the 3D printing system used.
Sheet lamination
Sheet lamination can be divided into two different technologies: Laminated Object Manufacturing (LOM) and Ultrasonic Additive Manufacturing (UAM). LOM uses alternating layers of material and adhesive to create products with visual and aesthetic appeal, while UAM joins thin sheets of metal using ultrasonic welding. UAM is a low temperature, low energy process that can be used with aluminium, stainless steel and titanium.
Photo Polymerization of materials
Photopolymerization can be divided into two technologies: stereolithography (SLA) and digital light processing (DLP). Both of these processes create parts in layers using light to selectively cure the liquid resin in the bath. SLA uses a single-point laser or UV light source for the curing process, while DLP uses an image of each layer on the surface of the bath. After printing, the parts must be cleaned of excess resin and then exposed to a light source to increase the strength of the parts. Any supporting structures also need to be removed, and additional post-processing can be used to create a better finish.
Ideal for parts with a high level of dimensional accuracy, these processes produce complex parts with smooth surfaces, making them ideal for prototyping. However, because the parts are more brittle than Fused Deposition Modeling (FDM), they are less suitable for functional prototypes. In addition, these parts are not suitable for outdoor use, since the color and mechanical properties may deteriorate under the influence of ultraviolet radiation from the sun. The required support structures can also leave stains that require post-treatment to remove.
How long does 3D printing take?
The print time depends on a number of factors, including the size of the part and the settings used for printing. The quality of the finished part is also important in determining print times, as higher quality products take longer to produce. 3D printing can take anywhere from minutes to hours or days - speed, resolution, and material volume are all important factors here.
Advantages and disadvantages
The benefits of 3D printing include:
Individual, cost-effective creation of complex geometries:
This technology makes it easy to create custom geometric parts without additional complexity at no extra cost. In some cases, 3D printing is cheaper than subtractive manufacturing methods because no additional materials are used.
Available start-up costs:
Because no molds are required, the costs associated with this manufacturing process are relatively low. The cost of a part is directly related to the amount of material used, the time it takes to make the part, and any post-processing that may be required.
Full customization:
Since the process is based on computer-aided design (CAD), any changes to the product can be easily implemented without sacrificing production costs.
Ideal for rapid prototyping:
Because the technology allows small batches and in-house production, the process is ideal for prototyping, which means products can be created faster than with more traditional manufacturing methods and without dependence on external supply chains.
Allows you to create parts with specific properties:
While plastics and metals are the most common materials used in 3D printing, there is also the possibility of creating parts from specially designed materials with desired properties. For example, you can create parts with high temperature resistance, water repellency or increased strength for specific applications.
The disadvantages of 3D printing include:
Strength may be lower than in traditional production:
While some parts, such as those made of metal, have excellent mechanical properties, many other 3D printed parts are more brittle than those made in the traditional way. This is because the parts are created in layers, which reduces their strength by 10-50%.
Increase in cost at large volumes of production:
Large volumes of production are more expensive when using 3D printing, because economies of scale do not affect this process in the same way as they do with other traditional methods. Estimates show that when comparing identical parts directly, 3D printing is less cost-effective than CNC machining or injection molding above 100 units, provided the parts can be made in the traditional way.
Accuracy limits:
The accuracy of the printed part depends on the type of machine and/or process being used. Some desktop printers have tighter tolerances than other printers, which means that final parts may differ slightly from sketches. While this can be corrected with post-processing, be aware that 3D printed parts may not always be accurate.
Post processing requirements:
Most 3D printed parts require some form of post-processing. This can be sanding or leveling to create the desired finish, removal of support posts that allow materials to take shape, heat treatment to achieve certain material properties, or final machining.
What is an STL file?
An STL file is a simple, portable format used by computer-aided design (CAD) systems to define the solid geometry of parts for 3D printing. The STL file provides input for 3D printing by modeling object surfaces as triangles that share edges and vertices with other neighboring triangles for the build platform. The resolution of the STL file affects the quality of 3D printing - if the file resolution is too high, the triangles may overlap, if the file is too low, the model will have gaps, making it unsuitable for printing. Many 3D printers require an STL file to print, however these files can be created in most CAD programs.
3D Printing Industries
Due to the versatility of the process, 3D printing finds application in various industries, for example:
Aerospace
3D printing is used in the aerospace (and astrospace) industry due to the ability to create lightweight yet geometrically complex parts such as blisks. Instead of assembling a part from several components, 3D printing allows you to create a product as a whole, reducing production time and waste of materials.
Automotive industry
The automotive industry has embraced 3D printing due to its inherent weight and cost savings. It also allows rapid prototyping of new or custom parts for testing or small-scale production. So, for example, if a particular part is no longer in production, it can be produced in a small batch to order, including the production of spare parts. Or elements or fixtures can be printed overnight and ready for testing before larger production.
Medicine
The medical sector has found the use of 3D printing in the creation of custom-made implants and devices. For example, hearing aids can be quickly created from a digital file that is matched to a patient's body scan. 3D printing can also significantly reduce costs and production time.
Railway transport
The railroad industry has found a number of uses for 3D printing, including the creation of custom parts such as armrests for drivers and housing covers for train couplers. Custom parts manufacturing is just one application in the railroad industry, which also uses the process to repair worn rails.
Robotics
The speed of production, freedom of design, and ease of customization make 3D printing ideal for robotics. This includes work to create custom exoskeletons and agile robots with improved agility and efficiency.