Understanding 3D printing
30 minutes | 22 Nov 2019
This guide is designed to help you understand 3D printing and the considerations you need to think about before embarking on your project. If you already know what you’re looking for, you can go there now:
What is 3D printing?
3D printing vs. injection molding
3D printing or dip molding?
3D printing and tool technology
Material choices for 3D printing
Using fasteners on 3D designs
3D printing and hinges
Learning to 3D print
What is 3D printing?
3D printing, also known as additive manufacturing, builds up a component layer-by-layer into a physical object from a digital model. Many thin layers of material are laid down in succession to form the part.
The 3D printing process turns a whole object into thousands of tiny slices, meaning that each layer can be complex, and it can also create moving parts. This benefits design engineers who want to experiment with novel designs.
Initially, 3D printers were used to produce plastic components, with variable levels of quality. The 3D printer is still used as a prototyping tool to test out engineering designs or to give the engineer an early 3D model of a component that would then be produced via another engineering process. For specialized, complex parts, 3D printing can also be a great rapid manufacturing solution.
3D printing vs. injection molding
3D printing is an exciting technological advance within the manufacturing industry. Injection molding is a manufacturing process for producing parts by injecting material into a mold. Material for the part is fed into a heated barrel, mixed and forced into the mold cavity, where it cools and hardens into the shape of the cavity.
This process is used to make a wide variety of plastic products from electric cable enclosures to model construction kits, chairs and toys, and industrial products such as caps, cable hole grommets, panel fasteners and plugs.
Injection molding is fast, and complicated shapes can be made from both thermoplastic and thermosetting polymers, which is one of its main advantages. By harnessing automation technology, injection molding is ideal for producing high volumes of complicated shapes at high speed. Although the parts in each press can all be unique, the process is suited to mass production and economies of scale, rather than unique speed manufacturing like 3D printing.
Pioneers of 3D printing technology are regularly creating new materials and items that can be printed. This has led to assertions that 3D printing will soon replace traditional manufacturing methods such as plastic injection molding.
These claims are definitely premature. Injection molding is an incredibly reliable, efficient method of production that accounts for over 75% of plastic parts used in industry.
There are three key reasons why plastic injection molding is here to stay:
Injection molding involves injecting liquid polymers into a mold, allowing it to adopt the shape of the mold before cooling it rapidly and removing the now-solid polymer. This process is significantly quicker than 3D printing that involves a liquid plastic filament being distributed in thin layers to create the object. Injection molding is therefore significantly quicker than 3D printing.
Due to 3D printing’s method of producing items via layering, it cannot produce the same consistently smooth surface finishes that are possible using injection molding. This layering method of production also leaves products with directional stress weaknesses that are not encountered by their injection molded counterparts.
Although advances are occurring regularly, at the time of writing the range and complexity of shapes that 3D printing can produce is currently limited in comparison to the shapes that are achievable using injection molding. The relative infancy of the technology means that software issues are still prevalent within the technology. Fixing both software and hardware bugs in the new technology can prove to be costly and time consuming.
It is possible to combine the technologies and use 3D printing to create the molds for the injection molding process. However these molds are normally created using photoreactive or thermoset resin, which breaks down faster than traditional metal molds.
Metal molds are capable of producing hundreds of thousands of products in comparison to the 3D printed molds. 3D printing molds are viable solutions for lower volume injection molding projects, as it can help to reduce the high initial costs associated with injection molding technology.
The price of both 3D printing and injection molding is dependent on the number of parts that are going to be produced. Injection molding is considerably more expensive to produce prototypes and small patches due to the initial costs of creating a steel or aluminium mold. Any subsequent alterations which can require whole new tooling. In 3D printing, once the prototype has been developed, it is a case of pressing print.
There have recently been new software advances that permit any prototyping issues to be resolved in the initial CAD design phase. This has helped to eliminate the need for multiple mold iterations and prototypes.
3D printing therefore begins with lower start-up costs, being especially cost effective for product runs of less than 50. However, costs increase with quantity due to the risk of misprints. Injection molding has higher initial costs, which drop rapidly with product volumes over approximately 60 items.
3D printing is a viable option for small volume batches, both to produce the product in its entirety, or to print the mold to reduce costs in the injection molding process.
3D printing or dip molding?
Dip molding and 3D printing have very different cost structures.
Dip molding is analogous to the methods used in traditional industry. Anything with a hollow inside can be produced through dipped molding. A heated metal mold is immersed in a tank of liquid plastisol. The heat from the mold attracts the plastisol, and the part is formed. Parts are cured, cooled and stripped. Typical products formed via this process include items such as pipes and pipe fittings, rubber gloves, and common tool handles.
Which is the most expensive?
Some dip molding tools are relatively cheap. For example, a dip-molding tool may cost around a fifth of the price of a typical injection-molding tool. Some dip-molding companies focus on achieving low plastisol costs by mixing their own plastisol and recycling the material. This can cut overall costs substantially.
3D printers vary widely in price. There are many 3D printing technologies on the market, with variations in quality and in the materials they can process. Metals and ceramics are much more costly to process than plastics, and these materials are often printed with industrial machines. However, low-cost 3D printers, do-it-yourself kits and open source software are increasingly making 3D plastic printing more accessible.
How 3D printing can reduce tool cost
One area where 3D printers can reduce costs is in the production of molds and tooling. For example, it is possible to manufacture a 3D-printed mold for a fraction of the price of a machined mold in a matter of hours. However, 3D printed molds are not as durable as machined molds and are only good for small runs. If multiple molds have to be 3D printed for one job, then the advantages of 3D printing can start to dissipate. As ever, it’s all about selecting the right tools for the right job.
3D printing and tool technology
Additive manufacturing has received a lot of attention as a means of producing designs rapidly, helping design engineers make prototypes with novel designs, and as a means of producing small runs of final parts quickly.
Perhaps inevitably, as the technology has advanced, engineers have also become interested in the potential of additive manufacturing for producing tooling, including 3D printing for injection mold tooling. The advantages of 3D printed tooling here include reduced lead times, reduced cost, and the potential for increased design flexibility.
Essentra has teams of custom solutions engineers and three 3D printers, or additive manufacturing (AM) machines, plus the ability to outsource AM work. “Primarily our AM machines are used for development of parts rather than mold tools, but we are looking at the potential development of mold tool technology via AM,” says Derek Bean, solutions engineering manager, Essentra.
AM technology may prove to be useful in producing inserts for mold tools in days rather than weeks. Historically, it has been used to produce plastic parts, but many AM machines now process aluminum, titanium and steel. The durability and post-processing of mold tools created by 3D printing tooling will be a challenge, Derek says.
“More work will need to be done on post-processing of parts to get a good surface finish. That may be quicker than machining out of a solid block of titanium, but there will be a process you have to go before you can get tens of thousands or hundreds of thousands of parts out of the mold tool.”
How tough will tooling be?
Chris Butler, process development manager, Essentra, says there are a lot of questions concerning the longevity of 3D printed tooling, and how long it will last compared to steel tooling. “But we have produced 3D printed inserts via AM to put into steel bolsters to see how they perform. Rapid prototyping is going that way.”
Material choices for 3D printing
The material, or filament, you choose will depend on the application. Here’s an overview of some of your choices to help you get started.
Acrylonitrile Butadiene Styren (ABS)
Tough with good impact resistance, yet lightweight, ABS gives you a durable printed part. Think Lego®, which is made from ABS, and you’ll have a good idea of its strength. It’s also one of the most affordable 3D materials.
ABS can stand up to very high temperatures before it starts to deform. One drawback to ABS is the fumes – and the odor – emitted when it reaches its melting point. Printing should be done in a space with excellent ventilation. You’ll also need to control the material’s cooling via temperature to prevent warping. Parts also tend to shrink, which creates dimensional inaccuracy. However, it’s also UV resistant and water permeable, making it a good choice for outdoor applications.
Common ABS applications:
- Automotive hardware
- Prototypes and fit testing: simulate the form, fit, and function of an end-use part’s performance
Polylactic Acid (PLA)
Another low-cost option, PLA is extremely popular in desktop 3D printing. One reason for its high demand is that it’s derived from renewable sources such as corn and sugarcane, making it biodegradable. It can be printed at low temperatures and you don’t need a heat bed.
It emits a sweet fragrance when printing, making it a more desirable choice than ABS for some people. However, it depends on the application. While it has better dimensional accuracy than ABS, PLA lacks ABS’s durability.
Common PLA applications:
- Cups & cutlery
- Test and calibration
PP is FDA approved, making it ideal for food storage and medical applications. However, this doesn’t translate to 3D printing. The reason is the printing process. With layer upon layer being added, it gives bacteria places to lodge itself.
Semi-rigid and lightweight, PP can be a difficult material to 3D print due to its semi-crystalline structure. This can result in printed parts warping significantly upon cooling. If you can master PP, you’ll have a material with good chemical, impact and fatigue resistance, making it ideal for low-strength applications. However, take note: PP can be expensive.
Common PP applications:
- Living hinges
- Straps, such as for watches
Polyethylene Terephthalate Glycol-modified (PETG)
PETG is version of PET but combined with glycol to give the material desired characteristics for 3D printing, e.g. transparency. The material is very easy to 3D print and can be done so at lower temperatures while increasing its flow speed. This means you can print your part quickly. Unlike PP, this makes PETG food safe for 3D printing. PETG gives you a smooth, glossy surface, but look out for thin ‘hairs’ caused by stringing.
It’s also strong and provides higher impact resistance than ABS, and excellent weather resistance, including the ability to withstand UV rays.
Common PETG applications:
- Snap-fit parts
- Concept models
Strength, durability and flexibility are nylon’s claim to fame. As a 3D material, nylon is abrasion and heat resistant, and has a low friction coefficient. It’s perhaps the most versatile material for 3D printing. Print it thin, and it’s flexible. Print it thick, and you’ve got superb dimensional stability during printing. Nylon also prints without emitting unpleasant odors.
There are a few drawbacks to the material, however. It’s prone to warping, but a heated bed can prevent this problem. Nylon is also ill-suited for humid environments.
Common nylon applications:
- Cable ties
- Screws, nuts, bolts & washers
Acrylonitrile styrene acrylate (ASA)
ASA is similar to ABS. It was first developed to offer a more weather-resistant option, which is why it’s popular in the automotive industry. As a 3D material, it’s rigid, strong and fairly easy to print.
ASA is also extremely resistant to chemical exposure and heat, and warps less during printing. However, it can crack if your cooling fan blows too hard on your item as it prints, so make sure to make appropriate fan adjustments.
Vulnerability to warping is still an issue, and ASA also shares the undesirable quality with ABS of unhealthy fumes and unpleasant odors being emitted during the printing process. Like ABS, make sure generous ventilation is in place. It has limited dimensional accuracy, and the print layers are likely to be visible.
Common ASA applications:
- Outlet covers
- Outdoor electronics housings and brackets
- Automotive prototypes
High strength PC’s impact and heat resistance makes the material ideal for demanding applications and harsh environments. It’s one of the strongest filaments you’ll find for 3D printing. It can bend without cracking or breaking, which is why it’s often used in applications where slight flexibility is needed.
By itself, PC requires printing at high temperatures, but you’ll find that most filaments contain additives that enable it to be printed at lower temperatures. However, printing at low temperatures can cause layers to separate. To offset this, use a 3D printer with an enclosed build volume that can withstand high bed and extruder temperatures. Finally, PC also absorbs moisture from the air, which can cause defects during printing if you’re not careful.
Common PC applications:
- Electrical components
- Mechanical components
- Automotive components
- Electronic cases
Polyvinyl alcohol (PVA)
PVA is water soluble and used as a support material in 3D printing. It’s especially good for enabling you to print complex shapes, overhangs and details features. This is because it dissolves in water, leaving no marks on the surface of the print. PVA works well with PLA and Nylon, as it requires the same operating conditions.
The downside is that it’s not cheap. There’s also a chance of PVA clogging if the nozzle is left hot when not extruding, so pay attention to what you’re doing.
Common PVA applications:
- Quick prototypes
Metal powder—this might be copper, iron, brass, titanium or stainless steel – is mixed with a thermoplastic, which makes the material heavier than typical plastics. You’ll need a wear-resistant nozzle with a metal-filled filament, as it’s an abrasive material when extruded through the hotend.
While the metal finish is aesthetically pleasing, it is an expensive material and printed parts are extremely brittle. Copper and bronze are used as 3D materials, though not so often in powder-bed processes. Because of their conductivity, they’re favored by electrical engineers.
Common metal applications:
- Museum replicas
- Visual arts
- Copper & brass: electrical engineering
Polyether ether ketone (Peek)
This material should be used by experts on an industrial 3D printer. The reason is safety. PEEK is resistant to high temperatures, so in order to print it, the 3D printer has to reach upwards of 752˚F (400˚C). Assuming you follow this directive, you’ll have an incredibly durable and hardwearing material.
PEEK has high impact strength and chemical, water and wear resistance. As a 3D material, it’s used for demanding applications across a range of industries. Peek is expensive, but you’ll get a lightweight, yet strong 3D printed part in return, and one capable of printing complex geometries.
Common PEEK applications:
- Loadbearing orthopaedic implants
- Aircraft structural components
- Automotive fuel management systems
Materials at a glance
|Heated bed not required|
Using fasteners on 3D designs
You have a 3D printed design that needs fasteners. What are your best options? First, let’s look at threaded inserts, which require an increased wall thickness.
Inserts with external threads
These are popular due to their easy installation and production quality. However, we are talking about 3D printed parts, so robustness is an issue. Threaded holes can wear quickly if the fasteners are taken on and off multiple times.
Inserts with external threads give you good pull-out strength, but the holes need to be tapped before you insert them. You should also know that brittle plastics can easily crack or chip when not tapped slowly. Poor tap alignment can adversely affect the integrity of the joint, so do this with care. A quick tip: applying a small amount of glue to the external threads before insertion can prevent them from rotating or unscrewing.
This type of threaded insert is a coil of wire. It has a square or diamond cross-section, and is designed for insertion into a damaged metal thread to restore its function. They’re a good option for tapped 3D printed plastic when you replace tapped plastic threads with metal threads.
Helical inserts are similar to externally threaded inserts, as both must have carefully tapped holes and can potentially unscrew. On the pro side, they are among the thinnest and least obtrusive insert options around.
Press-fit expansion inserts
Press these inserts into a hole and they expand when you install a screw, pressing knurls into the plastic. A tight fit is needed, but this can crack more brittle plastics. You can lessen the risk of this happening by increasing the screw boss diameter. Your other option is to glue the insert into a slightly larger hole.
A variation on the press-fit expansion insert. Its hexagonal “barbed” external profile gives you high torque-out and pull-out strength. Note, the barbs do not fully engage with brittle plastics such as PolyJet and VeroGray. Like its cousin, press-fit expansion inserts, glue can help.
You’ll use a soldering iron to press these inserts into an interference hole. Heated plastic then flows into the insert’s ridges and knurls and hardens to prevent twisting and pull-out. Because heat is a factor, these inserts should only be used with thermoplastics and other Fused Deposition Modelling (FDM) materials, where they’re easy to install and offer good pull-out strength.
3D printing and hinges
For manufacturers who want to rein in costs, additive manufacturing (AM), or 3D printing as it’s more commonly called, might be a smart option for parts you might least expect.
Consider the European Aeronautic Defence and Space Company (EADS). By 3D printing hinges for their Airbus A320, they reduced the hinge brackets’ weight by 35 to 55%, saving 22 lbs (10 kg) off the entire weight of the aircraft.
Now consider that reducing just over 2 lbs (1 kg) in weight from each aircraft of a 600-plus fleet of commercial aircraft could save nearly 20,000 gallons of fuel a year. Consider that in 2018, fuel accounted for 23.5% of the industry’s operating expenses worldwide, and you can appreciate the gains achieved from a simple hinge bracket. And that’s before the prevention of tons of CO2 being released into the atmosphere, thanks to the weight loss and thus, less fuel required.
The interesting part of all this is that the hinge bracket, while 3D printed, sacrificed nothing in strength or performance. The method of 3D printing utilised was Direct Metal Laser Sintering (DMLS) and the material, a titanium alloy powder.
The benefit of 3D printing is flexibility, which leads to cost reductions. Any modifications can be implemented right away, cutting down on lead times. For example, instead of a week, a hinge prototype can now be supplied in hours. Just in the development stage, money is saved. The technology of 3D printing is also less expensive than laser sintering or CNC cutting.
Like anything, so much rides on the type and size of the hinge being produced. CNC cutting can still be your most cost-effective option in the long run, but the point is, it’s no longer your only option. Industries are being redefined by 3D printing.
Learning to 3D print
3D printing is still a relatively new technology and although it is quickly becoming more widespread, not everyone knows how to use it. As a result, many companies are now offering training in 3D printing. For example, online courses are available that teach users about the various hardware and software behind the technology. Some manufacturers of additive manufacturing equipment such as Stratasys also offer their own training courses in how to use 3D printers.
Types of training
Manufacturers, designers and consumers are at different levels in their understanding of additive manufacturing. Luckily, a range of training options is available for everyone. For those with little experience, foundation training gives individuals with no exposure to 3D printing the tools to understand the terminology and the variety of technologies now on the market. In-depth technical training might go further, explaining how best to use additive manufacturing and the benefits for the supply chain and for design engineers. Lastly, advanced training is available for those looking to fully understand the machine itself, materials handling, and post-processing requirements.
Introducing the 3D printer
Courses may begin by introducing engineers and designers to the hardware used in 3D printing. The different components of the 3D printer will be discussed, such as the extruder nozzle and contact sensor, and their various functions. Engineers will learn how to set up and calibrate an industrial 3D printer so that the object is printed correctly on the printer base plate. They will learn about different software used to design 3D objects, and the importance of using 3D model repair to eliminate errors in the design that can cause defects in the final printed object. Whatever you're level of experience, there’s a course for you.
It’s a fact that 3D printing has transformed the aerospace industry. When this technology first appeared on the scene, the sector was an early adopter, and for good reasons. It’s been especially useful for creating prototypes, reducing lead times from weeks to days. Design flaws can be spotted and corrected sooner.
Another benefit: By rapidly producing parts on demand, they save quite a lot of warehouse space, time and money. Keep in mind that aerospace parts don’t benefit from economies of scale. Airplanes, for example, are made in smaller batches. Sometimes a part is specific to just one plane.
Considering all the benefits, 3D printing looks good, but is it really the best option?
Before you think traditional manufacturing methods have been side lined by the aerospace industry, think again. Unless you’re mass producing a part – and you probably aren’t – plastic injection molding really doesn’t make sense for the aerospace industry. Chalk one up for 3D printing.
However, it gets more interesting when we compare 3D printing with Computer Numerical Control (CNC) plastic machining:
For producing quality finished parts, however, the aerospace industry should also consider CNC plastic machining.
How does 3D printing rate for finished parts?
Every hour a plane is grounded it has huge cost implications. So when an airline modifies its cabin design, the gaps between existing and new layouts are urgent and expensive problems to solve. Luckily, 3D printing is helping to slash turnaround times, getting planes back in the sky quicker than ever before.
The first ‘aesthetically-pleasing’ 3D printed parts
3D printing is transforming the aerospace industry by reducing weight, strengthening materials and streamlining design. The number of 3D-printed parts used by Airbus alone is now in the thousands. Yet until recently, it was thought that 3D-printed components were not attractive enough to be on view.
Now that’s about to change. We already talked about Airbus A320’s use of 3D printed hinges. Now
Airbus has used 3D printing to create sleek spacer panels for filling end-gaps in a row of overhead storage compartments. The parts have been integrated into the cabins of its jetliners, passed stringent internal quality control and will soon be visible to passengers aboard Finnair’s A320 aircraft.
The traditional way of manufacturing new plastic cabin parts involves creating custom-made injection molding tooling. Given the precise nature of these components and the small numbers required, the process is complex and costly. In comparison, 3D printing a composite tool can shorten the lead time by months.
Using 3D-printing technology, Airbus has now enabled small-batch manufacturing of cabin components. And the results are not only quicker to produce than conventional molding techniques, they are also less expensive.
Airbus’s 3D-printed panels are 15% lighter than those made using conventional methods. This is an important consideration for jetliner interiors, where every ounce counts. The technology also lets the airline create additional features, such as lattices inside the panels, without additional manufacturing costs.
Emirates employ cutting-edge SLS technology
Airbus aren’t the only one to see the potential of additive printing for cabin interiors. Emirates has also ventured into 3D printing of components for aircraft cabins. The airline is using selective laser sintering (SLS), a 3D-printing technique to produce video monitor shrouds. Using SLS, the shrouds can be up to 13% lighter than traditionally manufactured components without compromising on structural integrity or cosmetic appeal.
The SLS technology uses a laser-to-sinter powdered plastic material into a solid structure based on a 3D model, which is different from the fusion deposition modelling technique normally used for printing 3D aircraft components. The technique uses a new thermoplastic which has superior flame resistance qualities and a professional finish worthy of commercial aerospace applications.
Having undergone structural, durability, flammability and chemical tests, the shrouds are in the process of receiving European Aviation Safety Agency certification. Once approved, they will be installed on select aircraft and tested over the following months to observe their on-board durability.
Saving airlines time and money
3D printing enables airlines to print components on demand, increasing efficiency and productivity. With the SLS technique, it’s even possible to print more than one component at a time. By reducing component production times, they will no longer have to hold a large inventory of spares or endure long wait times for replacements.
Emirates estimate that using 3D-printing technology can decrease operational and manufacturing costs by up to 30%. One of the largest cuts in expenses is the elimination of intermediaries in shipping and manufacturing that comes from being able to print on demand.
3D printing in space
The on-going supply chain from Earth to the International Space Station (ISS) has traditionally made space exploration expensive and slow. If astronauts needed an item, it would go up with the next launch, which might be months away. Since 2014, that’s old school.
Now if the astronauts need something, for example, a wrench, NASA emails them a CAD file and they use 3D printing to make it themselves. But what about printing actual satellite structures?
The next phase of 3D printing in space
The challenge here is that any large structure would have to be produced outside of the space station. It’s impossible to use a 3D printer in zero gravity, however. For starters, the part has no support. The machine has to somehow shape the part in the vacuum of space.
Also, the machine and the printing material would have to be far more resistant to space conditions than that used inside the space station and possess different characteristics. One solution is to integrate these machines inside of nanosatellites. A more efficient solution is set to be launched this year: Archinaut, a machine composed of a 3D printer and robotic arms to assemble the parts of the structure.
A new plastic for space
Polylactic Acid (PLA) and Polyvinyl Alcohol (PVA) are not resistant enough to be used with 3D printing in space conditions. To work, the printing material must have properties to resist extremely low and high temperatures.
A new kind of plastic is planned for Archinaut, made of polyetherimide/polycarbonate (PEI/PC). It’s stronger than the plastic printed inside of the Space Station. Polyetherimide and polycarbonate are two different thermoplastics, mostly used in engineering. The benefit of these plastics: they’re resistant to UV light and atomic oxygen, and in a vacuum, they won’t emit particles. Throw into this mix the advantage that they’re easy to model to create the shapes needed with precision, and you have the ideal material for space.
Metal is also being explored as a material for 3D printing in space, with a machine based on binder jet technology. Instead of gravity, a powerful jet of air is used to stabilize the part.
3D printing with material from space
Another interesting angle is extracting raw materials from space. U.S. companies Planetary Resources and 3D Systems have already created a 3D printed part from raw material contained in a meteorite. To create the part, the meteorite material was pulverized and transformed into a powder and then 3D printed.
Other uses for 3D printing in space
Imagine astronauts creating accurate 3D dimensional maps of their environment. The European Space Agency and the CNES (French National Space for Space Research) have already done this to help find the best landing site for the Rosetta mission to study a comet. With the aid of a 3D map, they chose 67P/Churyumov–Gerasimenko (67P/C-G), a Jupiter-family comet.
When NASA announced a contest to design habitats for life on Mars that were technologically and economically viable, a French company responded with 3D-printed housings.
The uses for 3D printing in space are proving limitless. If we can think it, we can build it.
The beauty of 3D printing is that it can create bespoke parts quickly and cheaply. Engineers send a computer-aided design to the AM equipment. Following those instructions, the equipment adds successive layers of liquid, powder, or sheet material to fabricate an object in 3D.
In 2018, 3D printing went a step further. Research from Nottingham University in the UK proved it can also work on the molecular scale, potentially increasing the use of 3D-printed devices in electronics, quantum computing and healthcare.
The research, led by Dr Victor Sans Sangorrin from the Faculty of Engineering and Dr Graham Newton from the School of Chemistry, used photochromic molecules, which change color when exposed to light combined with a custom-made polymer. Specifically, the photo-active molecule – a nano-structured tungsten-containing polyoxometalate – changes from colorless to blue when irradiated with light, then back by exposure to oxygen from the air. This was printed as a composite with a polyoxymethylene polymer, a class of materials used as engineering thermoplastics due to their stiffness and low friction.
In the academic journal Advanced Materials, the researchers explained, “In theory, it would be possible to reversibly encode something quite complex like a QR code or a barcode, and then wipe the material clean, almost like cleaning a whiteboard with an eraser. While our devices currently operate using color changes, this approach could be used to develop materials for energy storage and electronics.”
Electronics isn’t the only industry experiencing breakthroughs with the aid of 3D printing. In June 2018, the Dutch city of Eindhoven announced that the world’s first habitable 3D-printed homes would be built, transforming the construction industry – 3D printing generates less waste in building materials while also making it easier to customize homes to individual needs. The homes will also solve the problem of a shortage of bricklayers in the Netherlands, which drives up construction costs.
The futuristic-looking houses are designed to be as much a work of art as they are functional. The goal is that the small community will resemble a sculpture garden.
As part of Project Milestone, five concrete houses will be printed. The collaboration between Eindhoven University of Technology and other partners will ensure that the houses meet living standards.
Essentially, the 3D printer being used is a large robotic arm with a nozzle that squirts out a specially formulated cement. Project Milestone’s first house will be relatively simple: three rooms, single story with floor space of just over 1,000 square feet and walls just under two-inches thick. The foundations will be built using traditional methods.
The team plan to follow that up with multiple-story homes that feature three bedrooms, patios and balconies. Each subsequent house will be built by applying knowledge learned from the previous house. Parts will initially be printed at the university, but to reduce costs, the project team will work towards bringing the entire operation to the construction site.
Only the exterior and inner walls of the first of the new homes will be made using the printer. The hope is that by the fifth house, the drainage pipes and other installations will also be printed.
What happened next?
A month after the announcement for the planned 3-D houses in Eindhoven, a French family one upped the Dutch and moved into a 3D-printed house designed by researchers at the University of Nantes. A 3D-printing robot built the house in 54 hours using specialist plastic polymer and concrete.
These are revolutionary steps, but in both instances, the projects are not on any grand scale.
Consider that 3D printing a house isn’t a simple matter of pushing a start button on a printer. It requires knowledge of everything from structural engineering and materials science to artificial intelligence and architectural engineering. But with 3D printing, it’s about to get a lot more interesting.
Large-scale 3D printing on the way?
With rapid population growth in Saudi Arabia, a housing crisis is already underway. According to The National in 2016, brokers claimed that 400,000 affordable homes would be needed to answer immediate demand from middle-income households. Prior to that announcement, the kingdom’s housing ministry said they needed 3.3 million new homes over the next 10 years.
Enter Chinese 3D-printed construction firm, WinSun, who will lease 100 3D printers to a Saudi Arabian construction company in a deal worth $1.5 million U.S. The plan is to print houses on 30 million square meters.
WinSun claims that they built 10 houses in a day, costing $5000 each with what they call a ‘top-secret’ cement mixture made from recycled materials. Officials at UAE University and University of Swinburne in Australia raise doubts over WinSun’s claims, but scepticism has not slowed the company down.
They also have a contract for 20,000 single-story homes in Egypt. They’ll provide the printer and printing material and the houses will be built and assembled onsite.
Is large-scale 3D printing hype?
Maybe, but how can anyone say until we see the results in Saudi Arabia and Egypt?
According to Seyed Ghaffar, Assistant Professor in Civil Engineering and Environmental Materials at Brunel University London, “. . .there is still some way to go before additive manufacturing technology can deliver on its potential. There are several different components of additive manufacturing, each of which must be developed and refined before the process can be successfully used in large-scale construction.”
Those components include:
1. Printable Feedstocks
These are the materials printed that create the end product. The most important one, for large-scale construction, anyway, is concrete. These printable feedstocks are usually made from a mixture of materials, such as soil, sand, crushed stone, clay and recycled materials. These are then blended with a binder, typically Portland cement, fly cash or polymers. Additives and chemical agents are then added that enable the concrete to quickly set. When this happens correctly, the layers can be immediately deposited.
The trick here is getting the mixture of the materials just right. Otherwise, the feedstocks will set while still in the printer. Ghaffar explains that different grades of feedstock aren’t there yet; they’re still being formulated and developed. Only when this happens can 3D printing create different structural elements, such as load-bearing and large-scale building blocks.
2. The printer itself
A lot is demanded from the printer. It must have a powerful pump that can work to the scale of the construction industry’s requirements. The only way to tell that is to test the pressure and flow rate of the printer with different feedstocks.
The speed and size of the printer is also crucial in the desired print quality. Achieving a smooth surface, perfectly square edges and a consistency in width and height for each layer is part of the picture.
Another aspect to consider is the speed that the materials are transferred. This is measured in centimetres per hour and determines how quickly or slowly construction progresses. Slow down the feedstock material’s setting time allows the printer to work faster. The flip side is that the feedstock material is at risk of hardening inside the printer system. What needs to happen is printing that can deliver the feedstock materials at a constant rate. This will enable the layers to blend together evenly.
3. Bringing it together: geometry
Geometry, explains Ghaffar, is ‘the final piece of the puzzle.’ The printer and feedstock material must be set up correctly in order to produce full-size building blocks ‘with smart geometry which can take load without reinforcements.’ Shape stability of the truss-like filaments is everything. This is where strength and stiffness to the printed parts come from.
Ghaffar reckons it will be 10 to 15 years before we see 3D printing able to produce on a large-scale project. For that to happen, scientists need to experiment with the mix ratios of feedstocks. They also need to work on a printing system that can handle rapid manufacturing of building blocks. When those elements happen, 3D printing can accomplish the bigger picture in construction.
Winsun, however, feels the time is now.
The technology of 3D printing is going beyond saving time and money for manufacturers. Now it’s saving lives. In February, surgeons in Wales removed a tumor the size of a tennis ball from the chest of a 71-year-old grandfather. In the process, they had to cut away three ribs and his breastbone.
Normally, the ribs and breastbone would have been reconstructed with a cement prosthesis. Instead, surgeons gave him a 3D implant. The prosthesis was designed at the hospital and printed in Wales, with titanium used to give a stronger alternative to the traditional method, reducing surgery time by around two hours – an important factor given the patient’s age.
This isn’t the first time that 3D printing has been applied to medicine. In 2016, the Harvard Business Review reported that experts in the U.S. had developed 3D-printed skin for burn victims and airway splints for babies with tracheobronchomalacia, an illness that makes the airways around the lungs prone to collapsing.
The airway splints are especially significant because they are the first 3D-printed implant made for kids, designed to grow with the patient. They only cost about $10 per unit.
Cost-effective medical solutions
The technology is making financial sense as well. The older techniques of making a prosthesis was based on removing material by cutting, drilling and chopping, creating waste and extraction costs.
With 3D printing, objects from a digital model are created by successive layers of material being assembled on top of one another. This process increases precision and eliminates room for errors.
Surgical tools that have been 3D printed include forceps, hemostats, scalpel handles and clamps. They come out of the printer sterile and costing a tenth of steel tools.
Scientists at Princeton University are exploring the viability of combining electronics with tissue, having created a bionic ear with 3D printing. Still in the research phase, the ear can hear radio frequencies far beyond the range of normal human capability.
In Zurich, researchers have developed an artificial heart made of silicone. With pressurised air that inflates and deflates the heart, it beats in a natural way for about 30 minutes. While the team is working to improve their invention, the prototype represents another stage in the advancement towards replacing human hearts without transplants.
Experts say we are still about a decade away from printing out an entire working human organ for surgical use, scientists have managed to print kidney cells and the basis of a liver. The Heriot-Watt University of Edinburgh has bio-printed stem cells. The goal is to eventually print cells directly into the body.
Bio printing, the on-demand production of living tissue, may prove to be the most revolutionary development. It allows researchers to create human tissue with 3D printers and the patient’s own DNA. With biodegradable scaffolds, doctors can print an organ’s framework. They can then inject it with a patient’s own living cells in the precise area where they’re most likely to grow naturally. This reduces the risk of rejection, because the patient’s own cells are injected into the bio printed material.
The challenges going forward
One hurdle to widespread adoption is the lack of any regulated process for printing biological material. Physicians also need to be educated on the possibilities of 3D printing. Another obstacle is the scarcity of printers with the capabilities to produce living tissue. Currently printers are mostly located in research and development locations.
That brings up another problem: materials. Printers will need to evolve to produce multiple materials as hard as bone and as soft as skin. Another hurdle to bio-printing is developing software sophisticated enough to create the digital model of a heart or liver. Developing software that can take an MRI/CT to printed part takes expertise that is not yet widely available.
The technology of 3D printing will continue to advance, so these challenges will likely be overcome sooner rather than later.
Industries: Formula 1
With more than £1.8bn spent by teams during the 2017 season, Formula One is a laboratory for manufacturing’s most advanced techniques. And with points often separated by the finest of margins, the race to develop better parts is almost as frantic as the one taking place on the track.
F1 race cars are constantly refined and fine-tuned, their parts forever being replaced and upgraded. In the hunt for marginal gains, teams scramble to design performance-enhancing components, manufacturing small runs of specialised parts in all kinds of shapes, sizes and composite materials. And this is precisely why 3D printing is ideally suited to Formula One.
Renault Sport Racing F1 Team began experimenting with 3D Systems’ printing technology over 20 years ago. Now with nine printers on-site at its headquarters in France, Renault says 3D printing has become invaluable – especially for wind tunnel testing as it allows a rapid development of parts.
F1's first 3D printer in the pit lane
An increasing number of components on race cars are now made this way. Yet to take it a step further, the McLaren F1 Team takes a 3D printer to the track for race weekends. With a 3D printer in the pit lane, the team can now create small modifications to the front or rear wings and areas of bodywork in an attempt to gain an edge over their rivals.
In 2017, McLaren signed a four-year deal with leading US 3D-printing company, Stratasys, to implement the additive manufacturing technology into their workflow, using 3D printing to produce various parts from a hydraulic line bracket to brake cooling ducts and a rear wing flap. The parts are produced using fused deposition modelling (FDM) and PolyJet printing technologies for both prototypes and core, race-ready components.
“The main purpose of the trackside Stratasys uPrint SE Plus 3D Printer is to produce parts and tooling on demand for immediate evaluation during tests and races”, said Neil Oatley, Design and Development Director at McLaren Racing. “We do the design and re-design at our base in Woking and then send that to the team at the track. Crucially, this gives us the invaluable advantage of being able to fit extra pieces on the car, which we otherwise wouldn’t be able to do until the subsequent race.”
Accelerating development times
To construct a brake-cooling duct, McLaren created cores in a water-soluble material using a 3D printer then used those to make functional carbon-fibre composite parts. To increase downforce in the rear wing flap, the team used Stratasys’ Fortus 900mc 3D printer to create a high-temperature ULTEM mould in three days, dramatically reducing production time.
In addition to the trackside printing capability, McLaren also uses 3D printing for tooling and injection-mold tool creation, improving overall production efficiencies by shortening manufacturing times and enabling the team to react more quickly. The larger parts are made at McLaren headquarters in the Surrey, UK, which is reportedly home to Stratasys 3D printing equipment.
“For parts made at the factory, we are using Nylon 12CF, which is stiffer and stronger,” said Oatley. “We use this material to create a structural bracket to attach the hydraulic line on last season’s car.
This was produced in only four hours, whereas it would have taken an estimated two weeks using traditional manufacturing processes. The incremental gains we make from these parts, collectively make a big difference over the course of a season.”
What’s happening today
Jabil, a U.S. global manufacturing services company, worked with the Renault F1 Team to produce 3D printed car parts for its F1 car that competed in the 2019 Formula One World Championship.
The sport’s governing body, Fédération Internationale de l'Automobile (FIA), has turned to 3D printing to help them determine the design, rules and regulations of its 2021 cars. A prototype car at 50% scale enabled by 3D printing has undergone extensive wind tunnel testing to determine what the new rules are.
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