It’s an amazing feeling to realize that the technology that could rule the world in 10 years from now might not even be invented as of today! A great example from recent past would be the smart phone! Until, June 29, 2007, when Apple, under Steve Jobs released the first iphone, little did people know or imagine that a smart phone would become simply unavoidable in the recent future. From hunting jobs to booking a cab or from finding a date to being able to easily ignore your family at the dining table, there is almost nothing you cannot do with your phone today.
One such technology with adequate amount of potential to change the ways of our lives in the future is 3D printing. Synonymous to additive engineering, 3D printing is a manufacturing process has found its application in a vast number of industries of all kind. Before we get into the applications, let’s look into what 3D printing really is?!
What is 3D Printing or additive engineering?
3D Printing, as the name suggests is a mode of printing where a three dimensional structure is constructed using Computer Aided Design (CAD). Just like how 2D printers like inkjet or laser printers lays down ink in a paper (one layer) in a particular manner controlled by a computer to create an image, 3D printers lay down material or cure in a bunch of layers to create the three dimensional object.
Did it happen overnight?
Did the smart phone happen overnight? Well, the answer to both these questions are no! In fact, the first ever smart phone was developed and released in 1994 by IBM. It was called Simon! It had touch screen capabilities and also could run multiple applications like calculator, calendar etc. Similarly, although most of the work in 3D printing technology and its potential were realized in the recent half of the 21st century, the first recognised work in 3D printing goes back to the 1950s. Raymond F. Jones in his story, "Tools of the Trade," published in the November 1950 issue of Astounding Science Fiction magazine, described the general working and procedure of 3D printing. He described it as a "molecular spray" in that story. The first patent in this technology was made in 1971 by Johannes F Gottwald. He patented the liquid metal recorder, a continuous Inkjet metal material device to form a removable metal fabrication on a reusable surface for immediate use or salvaged for printing again by remelting. In 1974, David E. H. Jones laid out the concept of 3D printing in his regular column Ariadne in the journal New Scientist. Early additive manufacturing equipment and materials were developed in the 1980s.
Types
There are 7 additive manufacturing technologies that are used in 3D printers today.
1] Fused Deposition Modeling (FDM):
They work by a process where a spool of filament of solid thermoplastic material (PLA, ABS, PET) is loaded into the 3D printer. It is then pushed by a motor through a heated nozzle, where it melts. The printer’s extrusion head then moves along specific coordinates, depositing the 3D printing material on a build platform where the printer filament cools and solidifies, forming a solid object. This is the most common type of 3D printer as it is cheap and a wide range of materials can be printed. It is limited by being brittle, therefore unsuitable for mechanical parts. It also has a higher cost than SLA/DLP. Common applications for FDM include electrical housings, form and fit testings, jigs and fixtures, and investment casting patterns.
2]
Stereolithography Printer (SLA):
SLA is the world’s oldest 3D printing technology.
It was invented by Charles “Chuck” Hull and his company, 3D systems cooperation
in 1986. It works by a 3D printing method called Vat Polymerization where a
material called a photopolymer resin is selectively cured by a light source
(generally a laser beam). This is a costly process and is not suitable for mass
production.
3] Powder Bed Fusion Technology:
A} Selective Laser Sintering (SLS):
In this type, a bucket of thermoplastic powder (Nylon 6, Nylon 11, Nylon 12) is heated to just below its melting point. Then, a recoating or wiper blade deposits a thin layer of the powder usually 0.1 mm thick onto the build platform. A laser beam begins scanning the surface and selectively solidifies the required cross section of the object. This process is called sintering. Thus the product is built layer by layer. The advantage of SLS is that functional parts can be made using this method. However the machine space is large and the process has a very high lead time and hence, costlier than FDM or SLA.
B} Direct Metal Laser Sintering and Selective Laser Melting (DMLS & SLM):
These processes use Metal Powder Bed Fusion technology. Here, a heat source is utilised to fuse metal particles one layer at a time. The process is similar to SLS but for metals. Typical materials used are metal powder, aluminum, stainless steel, and titanium. DMLS is used for producing parts from metal alloys. Instead of melting it, DMLS heats the metal powder with a laser to the point where it fuses together on a molecular level. SLM uses the laser to fully melt the metal powder to form a homogeneous part, in other words, it makes parts from single element materials, such as titanium.
C} Electron Beam Melting
(EBM):
They also use the Metal Powder Bed Fusion technology. Unlike DMLS and SLM, instead of a laser, it uses a high energy beam of electrons for inducing fusion between metal particles in a powder. EBM is generally faster and has better finish quality. But they can be used only with electrical conductive materials. They can be used to build strong functional metal parts and the ability to produce complex geometries. They are costly!
4]
Digital Light Processing (DLP):
DLP
is very similar to SLA. The difference is that DLP uses
a digital light projector that flashes a single image of each layer all at one
time - or does multiple flashes for larger parts. Light is projected onto the
resin by light-emitting diode (LED) screens or an ultraviolet (UV) light
source, such as a lamp. A Digital Micro mirror Device (DMD) helps to project the
light to the work surface.
Here it gets a little interesting. Since the projector is a digital screen, the image of each layer is made up of square pixels, so each layer is formed from small rectangular blocks called voxels! DLP has faster print times than SLA because each layer is exposed all at once, instead of tracing the cross-section of an area with the point of a laser. Common applications for SLA and DLP are injection mold-type polymer prototypes, jewelry, dental applications, and hearing aids. They have fine feature details and smooth surface finish. They are brittle, therefore unsuited for use as mechanical parts.
5] Material Jetting: [MJ]
In this type of printing, a jet of photopolymer is thrown on to a bed using an inkjet head in a fast linier manner, which is immediately hardened by UV light. Thus the bed moves down and the next layer is processed in the same manner. This method is really efficient in terms of how quickly it performs the manufacturing. It is also possible to make multilateral parts of all colours in one go. Imagine you want to manufacture a mallet. MJ works such that the plastic head and the rubber grip can all be manufactured in one go!
6] Binder Jetting Technology:
A} Sand Binder Jetting (SBJ):
SBJ is the 3D printing technology that uses the Binder Jetting process. The process is similar to SLS as it requires an initial layer of powder, in this case, sand or silica, on the build platform. It differs from SLS, in that instead of using a laser to sinter powder, a print head moves over the surface depositing droplets of binder which bind the powder together, producing each layer of the object. Sand Binder Jetting is a low-cost technology for producing parts and sand cast molds and cores.
B} Metal Binder Jetting (MBJ):
This process uses the Binder Jetting technology to produce metal parts. The metal powder is bound using a polymer binding agent. It allows the production of objects with complex geometries that are far beyond the capabilities of conventional manufacturing techniques. This process is economical and can be used for mass production. Although functional parts can be made, it requires secondary processes to have good mechanical properties.
7] Drop on Demand (DOD):
This process is similar to Material Jetting. One of the differences is that this uses a pair of inkjets. One deposits the wax-like build material, the second deposits the dissolvable support material. Like other typical kinds of 3D printing technology, a DOD printer follows a predetermined path for jetting material in a point-wise deposition, creating the cross-sectional area of an object layer by layer. DOD printers also use something called a ‘fly-cutter’ which skims the build area after each layer is created, ensuring a perfectly flat surface before starting the next layer. Hence these have very good surface finish and also retain the advantages of material jetting.
Why 3D Printing?
3D
printing is a fast, easy to use, single step manufacturing process used to make
an object. The restrictions imposed by traditional manufacturing methods like
milling and turning on what can be made are generally not relevant for additive
manufacturing. This means that complex
designs can be manufactured and hence provides the freedom of design. Not only does 3D printing allow more
design freedom, it also allows complete customization of designs. Also, subtractive manufacturing methods, such as CNC
milling or turning, remove a significant amount of material from an initial
block, resulting in high volumes of waste material. Additive manufacturing
methods generally only use the material needed to build a part. Most processes
use raw materials that can be recycled and re-used in more than one builds. As
a result, additive manufacturing process produces very little waste.
It also helps in risk mitigation by being able to verify a design by printing a production-ready prototype before investing in expensive manufacturing equipment (e.g. molds or tooling and jigs) eliminates the risk during the prototyping process. This helps with building confidence in one's design before making the large investments required for the mass production level.
Where are they used?
Let us keep aside the fact that 3D
printing can be used to make anything from little showcase products, or kitchen
utensils to parts of machines, automobiles and tanks, let’s look at some of the
most interesting applications:
1] Food Industry: A 3 foot 3D printer can now make your favorite food! Be it pizzas or chocolates, a lot of food companies are beginning to use 3D printers to make their food. There are three general factors that impact precise and accurate food printing: materials/ingredients (viscosity, powder size), process parameters (nozzle diameter, printing speed, printing distance), and post-processing methods (baking, microwaving, frying).
2] Fashion Industry: One unexpected application of 3D printing is in the fashion industry. 3D printed jewelry has become a popular niche for those searching for a unique look. With the introduction of 3D printers, jewelry-makers can experiment with designs not possible using traditional jewelry-making methods. In addition, 3D printers make it cheaper to produce individual, unique pieces of jewelry or customize pieces for customers. Even clothes are being 3D printed these days.
3] Construction Industry: Another
exciting application of 3D printing is in construction. Concrete 3D printing has been in development for years as
a fast and cheaper way to build buildings. Large-scale 3D printers specially
designed to print in concrete can pour foundations and build walls onsite. They
can also be used to print modular concrete sections that are later assembled
onsite. For example, this 3D printed concrete bridge in Shanghai, China was printed
in 450 hours at two-thirds of the usual cost. It was also installed with
detectors that relay information about stress and strain so the city can
monitor its status in real-time. In China, giant 3D printers were used to print
10 full sized housed in one day at a very cheap price.
4] Automobile Industry: For a 100
years, automobiles are being made using an assembly line. Local Motors is a
company in Tennessee, US, that has made a car completely out of 3D printing!
The car is called Accelerate! Is this how cars would be made in the future?
5] Oh… And here is our question…
So finally, can we print a human heart!?
One of the major challenges in the field of health and medicine is not having a sufficient number of tissues and organs that you can use to replace in patients. Patients wait days, months or even years for a living or deceased donor to provide them an organ. Until quite recently, the thought of being able to manufacture a heart was completely out of books. It was brought into the books by the advent of 3D printing which brought with it, 3D bioprinting. In 1999, The Wake Forest Institute for Regenerative Medicine in North Carolina, United States successfully printed a human bladder, which they were able to implant to a patient and 10 years after the implantation, the patient faced no serious complication. This was the first serious development into organ printing.
Well
technically, it’s not just the printing that is involved. The concept is the
same, where a computer model is fed into a printer that lays down successive
layers of the required part. In the case of organ printing, the material being
used by the printer is a biocompatible plastic. The biocompatible
plastic forms a platform or a scaffold that acts as the skeleton for the organ that
is being printed. As the plastic is being laid down, it is also seeded
with human cells from the patient the organ is being printed for. After
printing, the organ is transferred to an incubation chamber to give the cells
time to grow. After a sufficient amount of time, the organ is implanted
into the patient.
After
the bladder at Wake Forest, strides were taken towards printing
other organs. In 2002, a miniature, fully functional kidney was
printed. In 2003, Dr. Thomas Boland from Clemson University patented
the use of inkjet printing for cells. Multiple tissues and organs
have also been made using this technology as of today.
Let’s get back to our question now! Yes it’s true. The first successfully 3D printed artificial human heart was developed by the scientists at Tel Aviv University in Israel on April 15th, 2019. Although it is just a miniature prototype, it is the first time humans have successfully designed and printed a heart with cells, blood vessels, ventricles, and atria.The scientists, Tal Dvir, a researcher with Tel Aviv University's School of Molecular Cell Biology and Biotechnology and his team first removed some adipose tissue from some patients and then separated their cellular components. These cells were then used to induce the production of pluripotent stem cells, and non-cellular components such as collagen and glycoprotein were used to synthesize "individualised gels" to serve as material for 3D printing. Mind blowing right? Who knows, maybe 10 year down the line, hospitals will be printing the organs they need in their own printers!
The obvious next question is, how long would it be before we start making the whole human body? Gone are the days where robots are made of metal aren’t they? Well, it’s too early to answer these! But science and technology has little limitations.
Biodegradable Plastic!
Poly Lactic Acid or PLA is a biodegradable plastic material. PLA has become a popular material due to it being economically produced from renewable resources. In 2010, PLA had the second highest consumption volume of any bioplastic of the world, although it is still not a commodity polymer. Its widespread application has been hindered by numerous physical and processing shortcomings. 3D printers have made PLA more usable, hence is a great environment conserver!PLA is used as a feedstock material in most desktop fused filament fabrication 3D printers.
The road ahead!
3D
printing has changed and will continue to change not just our industry but our
very society. With widespread access to
3D printing equipment (as it is now getting smaller and cheaper), will come the
ability to purchase and print items from the internet in real time. For instance, if you need a custom-made cover
for your smart phone, all you will need to do is visit an online store selling
the same and get its technical prints. Then, you can choose the color you want
(maybe putting your name on it), download the final design to your computer,
and subsequently print it out.
While additive manufacturing has been around for more than 30 years, the majority of growth has occurred since 2010. This has to lead to a large number of 3D printers entering the industry, making it significantly easier for designers to access additive manufacturing technology. In 2015 alone, more than 278,000 3D printers valued under 5000 dollars were sold globally. The number of printers sold has doubled consistently since. What was originally a niche technology accessible only to a small segment of the manufacturing industry is now readily available and cost competitive method of part production utilized by a vast range of industries.
Additive manufacturing combined with machine learning can greatly help in mechanical and structural design and analysis. The idea is for example, you can ask the computer to provide you with the most efficient shape in terms of strength to weight ratio. The strength can be calculated by mathematical equations just like tools like Ansys and Abacus use, and the shape thrown at you is such that the cell mass or material is distributed only where it is required (so as to keep the maximum stress generated in the part below the maximum allowed level) and they can be easily manufactured by 3D printing. Hence, this will provide a lot of efficiency in the part and its application. This is impossible with subtractive manufacturing as it is not possible to make complex shapes and geometries out of conventional tools.
The first 20 years of 3D printing was used for prototyping. Going ahead 3D printing will start playing a major role in mass production of various products. This will change the industry at large. Instead of bringing in different parts from different places, 3D printing allows you to produce the required part from wherever you are. Well, we are lucky to have already been a part of the digital revolution in the world. Professionals across the globe believe that people of the 21st century are going to witness the fourth global industrial revolution. And 3D printing technology will provide the foundation to this global renaissance. Because now we can make things, whatever we want, with absolute freedom!!
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