3D printing offers engineers a cost-effective way to fabricate fast prototypes and end-use parts with highly complex geometries. Comprising a broad range of different technologies, 3D printing enables the fabrication of plastic and metal parts with potential cost savings and significantly shortened lead times. This guide goes over the basics of 3D printing, looking at key technologies, materials, and applications.
3D printing is a manufacturing technology for making three-dimensional parts from digital 3D models. The technology encompasses many different processes that have their own unique materials and applications. However, all printing technologies share the characteristic of constructing parts layer by layer following computer instructions.
The first 3D printing technology was invented in the early 1980s. Between 1981 and 1984, three distinct patents were filed for technologies that used UV light to cure photosensitive resins. The last of these was filed by Chuck Hull, who coined the term “stereolithography” and would go on to found 3D Systems. Other 3D printing technologies emerged in the late 1980s and early 1990s.
1987
1992
1994
3D printing experienced a boom in consumer activity in the 2000s and early 2010s as important patents expired, allowing new companies to make their own low-cost 3D printers. Since then, the market has skewed more towards industrial users, who use 3D printers to make high-value end-use parts.
The term “3D printing” is sometimes used interchangeably with “additive manufacturing.” However, 3D printing usually refers to consumer-level activity, while additive manufacturing is reserved for professional and industrial activity, typically on a larger scale with more expensive equipment. “Rapid prototyping,” another synonym, is becoming less common because 3D printers can now make end-use parts as well as prototypes.
How 3D printing works depends on the type of 3D printer, as different technologies function in different ways. However, although 3D printing technologies can vary significantly, all share a few common characteristics. The basic principles of 3D printing are:
3D printing starts with the development of a printable model. This can be achieved using CAD, 3D modeling, 3D scanning, or other means. The model must be designed in a way that can be realistically manufactured using the 3D printing technology — a process known as design for additive manufacturing (DfAM) — and converted into a file format such as STL or AMF. Using “slicing” software, the model is then converted into machine instructions.
A 3D printer fabricates a part by printing a series of two-dimensional layers that are fused together to form the complete part. How these layers are built depends on the technology and material. For example, an FDM printer extrudes molten thermoplastic from a nozzle, while a DMLS printer uses a powerful laser to selectively sinter particles of metal powder. Typically, the printer uses a system of motors to incrementally move the build platform or printing apparatus between layers.
When all layers have been printed, the finished print is removed from the printer, manually or automatically, and may then be subject to post-processing steps. Post-processing may involve removal of excess material, sintering of the part in a furnace, the addition of surface finishing treatments, etc.
3D printing technologies can be grouped into six major categories, with a few outliers. Classification can be confusing, as some technologies go by more than one name and there is a mixture of generic and proprietary nomenclature. For clarity, proprietary technology names have been capitalized in this guide.
Material extrusion refers to 3D printing technologies that melt feedstock and push it through a nozzle. The nozzle is able to deposit each layer of molten material in a complex two-dimensional shape as the printhead moves along the X and Y axes via a system of motors and rails. The molten material cools and solidifies after extrusion, allowing further material to be built on top.
The main material extrusion technology is Fused Deposition Modeling (FDM). That term is trademarked by Stratasys, so other companies may use “fused filament fabrication (FFF)” to refer to the same process. Large-format additive manufacturing (LFAM) 3D printers also generally use material extrusion technology, with pellets as feedstock rather than filament.
Most material extrusion printers use thermoplastics or reinforced thermoplastic composites as feedstock. Less common materials include metals and ceramics.
Vat photopolymerization was the original form 3D printing and remains popular today. It encompasses several processes, including stereolithography (SLA), digital light processing (DLP), and liquid crystal display (LCD) or masked SLA (mSLA). All use a light source to selectively cure layers of photopolymerizable liquid resin.
Some resin printers, known as “bottom-up” systems, print the part upside down, suspended from the build platform above the resin tank and light source. This can save money by requiring less resin but runs the risk of the suspended part falling from the platform.
Carbon’s Continuous Liquid Interface Production (CLIP) is a faster variant of vat photopolymerization.
Powder bed fusion (PBF) is a broad category of 3D printing technologies — most targeted at advanced professional or industrial users — in which powder granules are fused on a granular bed using a heat source. Depending on the technology type, the granules may be sintered or fully melted.
Unlike other 3D printing technologies, powder bed fusion spans both metal and plastic printing technologies. Direct metal laser sintering (DMLS), Nikon SLM Solutions’ Selective Laser Melting (SLM), and electron beam melting (EBM) are all techniques used to make industrial-grade parts from metal powders.
Selective laser sintering (SLS) and HP’s Multi Jet Fusion (MJF) are used to make parts from materials such as nylon (polyamide). One advantage of SLS printers over material extrusion is that unsintered powder supports the in-progress part, making support structures unnecessary.
Material jetting is a 3D printing technology that somewhat resembles 2D inkjet printing. During the process, printheads dispense droplets of material through a thermal or piezoelectric process. The material solidifies by cooling or UV light curing.
Material jetting processes include drop-on-demand (DOD) printing, Stratasys’ PolyJet 3D printing, and XJet’s NanoParticle Jetting (NPJ). Materials include photopolymers, metals, technical ceramics, and wax.
Binder jetting is a unique 3D printing technology that uses inkjet-style apparatus to deposit an adhesive binder onto a powder bed, fusing the powder into shape without the use of a heat source. It is sometimes known as “powder bed and inkjet head 3D printing.”
Although binder jetting cannot produce especially strong parts, it is compatible with a range of metals and ceramics and is also capable of producing full-color parts such as display models. Desktop Metal’s Single Pass Jetting (SPJ) is a form of binder jetting.
Directed energy deposition (DED) is a form of 3D printing in which a nozzle on a robotic arm deposits metal powder or wire onto a build platform, before a laser or electron beam melts the deposited material. The technology can produce large and strong parts.
Forms of DED include Sciaky’s Electron Beam Additive Manufacturing (EBAM) and metal wire 3D printing techniques like wire arc additive manufacturing (WAAM).
A less well-known form of 3D printing is sheet lamination (SHL) or laminated object manufacturing (LOM), which uses aspects of subtractive manufacturing. SHL machines print paper, plastic, or metal sheets into 3D shapes. Paper represents a low-cost feedstock for 3D printing.
What material is used in 3D printing? The answer to that question today is different to what it was in the 1980s. Across its diverse range of technologies, 3D printing now supports a broad range of materials, from low-cost thermoplastics like ABS to aerospace-grade titanium alloys. Here we focus on four major material categories.
The most widely used materials in 3D printing are thermoplastic polymers. These are plastics that can be melted into a pliable state, shaped using a technique such as material extrusion, then cooled and re-solidified to make a usable part. Printable plastics include commodity polymers, engineering polymers, and high-performance polymers.
Material extrusion processes like FDM use thermoplastics in filament form (long strings of extruded material wrapped around a spool). Consumer-level machines can print polymers like PLA, ABS, PETG, TPU, PC, and various nylons. Some filament manufacturers also produce blends — two or more thermoplastics mixed together — to create a balanced material profile. Dual-extrusion printers are designed to print a soluble or breakaway support material such as PVA or HIPS alongside the build material. High-temperature machines can print specialty materials like PEEK and PEI (Ultem).
SLS printers typically print polyamides (nylon) due to their sintering properties. Other suitable plastics for sintering include PP, PS, and thermoplastic elastomers like TPU.
Metal additive manufacturing processes can process a range of metal materials. The majority of technologies require the metal to be in powder form, though some technologies use metal wire or filament. Some powders are gas atomized to produce even particle sizes, improve flowability, and create higher-quality printed parts.
Common 3D printing metals include titanium powders for aerospace and biomedical applications, aluminum alloys for general-use printing, copper powders for parts like heat exchangers, and superalloys for aerospace parts.
Photopolymeric resins are light-activated polymers whose properties change when exposed to light. They contain a mixture of monomers, oligomers, and photoinitiators. 3D printing resin manufacturers may tailor their formulations to produce desirable characteristics such as strength, flexibility, or transparency.
3D printing resins come in liquid form and are typically deposited into the vat of a vat photopolymerization 3D printer. An exception is the Stratasys PolyJet process, which jets the material onto a build platform before curing it.
3D printing composites are, for the most part, thermoplastics reinforced with stiff materials like carbon fiber, fiberglass, or Kevlar. The reinforcing material can be “chopped,” with fibers oriented in random directions, or “continuous,” with fibers oriented in a single direction and consequently providing higher strength. Common base polymers for composites include nylons and ABS.
Most composites are produced in filament form for material extrusion 3D printing, but SLS machines can also process “loaded” composite powders. Composite filaments require hardened printing nozzles due to their abrasive nature. Metal 3D printing innovator Desktop Metal has developed composite printing technology that deposits continuous fibers from a secondary nozzle, resulting in high-strength parts.
Other 3D printable materials for various technologies include clay, technical ceramics like alumina and zirconia, gypsum plaster, wax, silicone, paper, and edible materials.
3D printed parts generally require post-processing before they are ready for use. Post-processing may involve manual cutting and finishing, though automated post-processing stations for 3D printing are becoming more widespread in industrial additive manufacturing.
Most 3D printing processes require the use of temporary support structures to print overhanging sections of a part and prevent collapse. These structures may be made from the part material or from a separate support material.
Support structures must be removed after printing. Manual tools like a bandsaw (metal parts) or knife (plastic parts) may be used, followed by sanding and polishing to disguise the blemish where the support has been removed. Some FDM printers use a second extruder to print specialty support structure materials, which may be either “breakaway” (brittle and easy to snap off) or water-soluble. For the latter, parts can be rinsed or placed in an ultrasonic bath to remove the support material.
Some 3D printing processes produce “green” parts or parts that require further treatment to improve their material properties. These post-processing steps typically require separate machinery such as ovens or debinding stations.
Binder jetting requires that the adhesive binder be removed from the parts after printing via heat or chemical treatment, followed by sintering to reduce porosity. Metal processes like DMLS may use special heat treatments like hot isostatic pressing (HIP) to reduce porosity and increase strength, especially for safety-critical parts. Vat photopolymerization parts may be subject to post-curing to increase strength.
3D printing processes like material extrusion and DED produce a poor, rough surface finish unsuitable for most end-use applications. This can be rectified with surface finishing treatments applied manually or with specialist equipment. Techniques include sanding, abrasive blasting, and chemical treatments such as acetone rubbing or vapor smoothing for thermoplastic parts. Parts may also be spray painted or dyed.
Metal parts may benefit from post-machining with a CNC machine to achieve tight tolerances or add standard features like holes and threads.
3D printing generally requires at least two types of software. Several free applications exist in each category.
Though initially developed and marketed as a prototyping technology, 3D printing or additive manufacturing now offers a broader range of applications. Some high-end 3D printers are built specifically to provide production-level quality and throughput.
3D printing, sometimes referred to as “rapid prototyping,” is a valuable prototyping process due to its low startup costs, freedom from tooling constraints, and short lead times. Design costs aside, the unit cost for a 3D printed part does not vary greatly depending on volume.
The affordability of 3D printing in low volumes allows R&D departments to iterate several designs across a range of materials. Lead times are exceptionally short compared to processes like injection molding or metal casting, in which tool production adds days or weeks to lead times. Some 3D printers can be operated in non-industrial environments, simplifying in-house prototyping.
Industrial additive manufacturing companies are increasingly marketing their hardware as a viable production solution. As industry regulators become more familiar with 3D printed parts, more end-uses become possible.
Although 3D printing at scale is slower than established mass production technologies like molding, several factors are contributing to the increased feasibility of production-level 3D printing. These include:
Production parts are often made from premium 3D printing materials such as engineering thermoplastics or high-strength metal alloys.
3D printing can be used to assist other manufacturing technologies via the printing of manufacturing aids like jigs and fixtures, often using high-performance thermoplastics. 3D printed tooling is another area of development, with printed metal molds typically lasting around 100 shots during injection molding. End-of-arm tooling and forming dies may also be 3D printed. Vat photopolymerization (and material extrusion to a lesser extent) has long been used to print disposable patterns for investment casting in fields like jewelry, while binder jetting can be used to make mold cores for sand casting.
3D printing is a digital manufacturing technology offering short lead times and affordability in small quantities. This makes it suited to on-demand parts such as automotive spares and repairs, parts for obsolete or legacy machinery, user-customized designs, and patient-specific medical implants or dental appliances. Such parts can be printed as needed rather than in batches. On-demand 3D printing may be combined with digitization of inventory to reduce warehousing and storage costs.
3D printing is used in a diverse range of industries, from aviation to healthcare. Some of the more notable sectors are listed below.
3D printing has little in common with traditional manufacturing technologies, which offers both advantages and disadvantages. While the technology can open up significant opportunities in some areas, it remains unsuitable for certain applications.
The fastest way to get started with 3D printing is to use a printing service bureau or manufacturing partner. However, it is becoming increasingly viable for SMEs and larger companies to invest in their own 3D printing equipment for in-house printing.
1. Versatility and ease of use
Despite the broad range of 3D printing technologies available, most newcomers opt for material extrusion (FDM) due to the low machine cost, wide range of materials, established user base that can provide support and solutions, and relative ease of use.
Consumer-level extrusion machines cost under $1,000 and high-quality professional-grade systems are available for less than $10,000. Most machines can be operated in non-laboratory environments.
Material extrusion is an ideal technology for prototypes, tough and durable plastic end-use parts, flexible parts, composite parts, and jigs and fixtures.
2. Fine details
The next most suitable technology for first-time users is vat photopolymerization, with machines available in a comparable price bracket to material extrusion. 3D printers in this category can generally produce parts with an excellent surface finish and detailed features.
Some resin technologies, namely DLP and LCD, are also much faster than material extrusion, as they can form entire layers at once. Drawbacks include weaker parts and more complex material handling and post-processing requirements.
Vat photopolymerization is ideal for the printing of detailed or miniature models, visual prototypes, translucent parts, dental devices, and jewelry patterns.
3. Advanced processes for high-level users
Experienced engineers and larger companies may find value in other 3D printing technologies, including powder bed fusion (SLS 3D printers or metal additive manufacturing systems). While the barrier to entry for such technologies is higher, parts can be made to a high quality and produced at scale.
DMLS is suitable for a range of end-use metal parts, while binder jetting is ideal for colored parts and sand casting cores. A process like HP’s Multi Jet Fusion may be suitable for parts with ultra-fine details being produced in small or medium-size batches.
Recommended 3D printing technologies for new users, namely material extrusion and vat photopolymerization, can be operated in a non-industrial workspace, but it helps to set up a dedicated 3D printing workspace.
When setting up a 3D printer workspace, consider the following:
To get started with 3D printing, other investments need to be made on top of the 3D printer. The most significant outlay is materials, as these need to be replenished in accordance with printing frequency. For material extrusion, commodity polymers are available for around $30 per kilogram, though high-quality engineering materials can cost at least 10 times that amount. Liquid resin is available at a similar or slightly higher price, though the total cost per part depends on factors like density, wastage, and support structures.
The cost of software depends on the level of sophistication required and any specific applications. However, many 3D printer users get by using only free software. Free 3D design solutions for 3D printing include Tinkercad and FreeCAD, while popular slicers like Cura and PrusaSlicer are also free. Professional and industrial applications (for design, slicing, and fleet management) are most commonly sold using a tiered subscription or software-as-a-service (SaaS) pricing model.
You will need tools and other components for in-house 3D printing. Different technologies necessitate different expenses. For material extrusion, start with the following:
Countless examples of 3D printed parts can be found across a range of industries. Here we look at three notable cases using different printing technologies.
Arizona’s Align Technology has changed the orthodontics world with its Invisalign clear aligners program, allowing users to straighten their teeth without braces. Vat photopolymerization 3D printing is at the core of its business, as the company prints roughly half a million parts every day.
The dental giant initially used 3D printing to fabricate a pattern (a model of a patient’s teeth) from which a thermoforming process was used to make the clear aligners. It had notably worked with SLA printing company 3D Systems. In early 2024 Align purchased 3D printing company Cubicure so it could print its aligners directly without the use of thermoforming.
Several footwear companies have used 3D printing to improve the quality of their running shoes. Since 2017, Adidas has been using the technology to make flexible, high-performance midsoles with complex infill patterns. At present, the company works with printing company Carbon to develop its “4D” line of shoes.
Another brand using 3D printing to advance footwear technology is New Balance, which has worked with Formlabs to print midsoles.
Metal additive manufacturing is playing an increasingly important role in the aerospace industry. Californian company Relativity Space is a pioneer in the field, using its Stargate metal wire 3D printing system to fabricate ultra-large metal parts. The company is currently developing its Terran R launch vehicle, set launch in 2026, that will feature a total of 13 3D printed Aeon R rocket engines.
Other 3D printers being used for rocket engine components include DMLS machines from EOS offshoot company AMCM and PBF systems from California’s Velo3D.
3D printing offers value-generating potential for many businesses across a range of industries. R&D departments can benefit from the rapid prototyping aspect of 3D printing, fabricating working prototypes in a matter of hours with more geometrical freedom than other fast processes like CNC machining. Furthermore, high-end systems and factory integration solutions have made 3D printing a viable option for large-scale part production. Several leading hardware vendors are focused on this area of 3D printing, which means industrial-grade systems will increase in quality and productivity over the next decade as further materials and applications become qualified for the process.
More like this:
29/10/2024
Additive Manufacturing
29/10/2024
Additive Manufacturing
.jpg)
25/10/2024
Additive Manufacturing
All uploads are secure and confidential