Newsflash

The drive for lightweight materials to reduce overall cost and environmental impact for automotive manufacturers is nothing new.  Fuel economy attracts car buyers too. That is how majority of steel parts have been replaced in F-150 pickup truck by aluminum parts, reducing overall weight over 500 pounds. Then there are alloys, carbon fiber and plastics composites.The ambition for lighter vehicles did not stop with alloys (magnesium, aluminum), and/or composites (glass, carbon fibers).  Recently, Japanese researchers at Kyoto University led by Professor Hiroaki Yano along with its industrial partners (Denso Corporation and Daikyo-Nishikawa Corporation) reported that they were developing cellulose nanofiber based materials for automotive as well as aircraft parts to reduce environmental footprint while increasing product performance.Inevitable questions are: 1) would these materials be cost effective? 2) What would be the service life of these products compared to the current ones? 3) How about the parts’ safety in situations like crash or fire?A final question that an automaker has to ask is: what would be the pay back time to replace current production line (machinery) to CNF based plastics line?Reference: https://www.japantimes.co.jp/news/2017/08/15/business/researchers-japan-use-wood-make-cellulose-nanofiber-auto-parts-stronger-lighter-metal/#.WbAIKeTXuUm...
We know polycarbonates mostly from its use in plastics water bottles, safety goggles, smart phones, structural panels (glazing) and the list goes on.  A quick look at Wikipedia gives a spectrum of applications.However, polycarbonates have its weaknesses along with the BPA (bis-phenol) controversy. Polymers such as polysulfates and polysulfonates have similar if not better mechanical properties than polycarbonates.  The issue has been how reliably scale-up the manufacturing process of polysulfates and polysulfonates?“Click chemistry” is a concept in organic chemistry by which highly reactive reactions provide high yielding products and require little to no purification.  The concept was introduced by Nobel Prize winner Professor K. Barry Sharpless in 2001.A recent work published in Nature Chemistry, by a team of researchers from The Scripps Research Institute (La Jolla), Lawrence Berkley National Laboratory (Berkley), California and Shanghai Institute of Organic Chemistry & Soochow University, China claimed that reduced cost of catalyst, product purity, and by-product recycling make their work ready to move from laboratory research to industrial process.Chemists are at work indeed!References:https://en.wikipedia.org/wiki/PolycarbonateK. Barry Sharpless et al; Nature Chemistry, 2017 DOI: 10.1038/nchem.2796...
In a recent The Atlantic interview Bill Gates made a wish on an energy miracle, “Here’s a source of energy that is cheaper than your coal plants, and by the way, from a global-pollution and local-pollution point of view, it’s also better”.  The race is on to find that source. One such energy source is solar energy. We all know that solar energy can be harnessed to generate thermal energy or electrical energy for use in the residential and/or in the commercial applications.  Any material that can store Solar Thermal Energy is called Solar Thermal Fuel (STF).  The quest to harvest solar energy, store the same and use it when needed has been the focus of research in industry and academia alike. For the first time, Professor Grossman’s team at MIT, Cambridge (USA) has come up with a new approach which uses polymer Solar Thermal Fuel (STF) storage platform utilizing STF in its solid-state.  According to the published article, researchers stated, “Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. This approach enables uniform films capable of appreciable heat storage of up to 30 Wh kg?1 and that can withstand temperature of up to 180 °C.”How the STF process works?Certain molecules (chemicals) can have 2 different stable structural forms. These structures are called conformations.  When original molecular conformation is exposed to sunlight, the molecule gets charged and the original conformation changes to the other and stay in that charged conformation for a long period.  The charged molecule snaps back to their original shape (conformation), when triggered by a very specific temperature or other stimulus generating heat in the process. Currently, developed polymeric film can release heat about 10 degree C above the surrounding temperature. Film property improvements are underway. German auto company BMW, has sponsored this research. Where the potential application lies - your guess is as good as mine.References:The Atlantic, p 56, November 2015Zhitomirsky, D., Cho, E. and Grossman, J. C. (2015), Solid-State Solar Thermal Fuels for Heat Release Applications. Adv. Energy Mater., 1502006. doi:10.1002/aenm.201502006...
In a recent The Atlantic interview Bill Gates made a wish on an energy miracle, “Here’s a source of energy that is cheaper than your coal plants, and by the way, from a global-pollution and local-pollution point of view, it’s also better”.  The race is on to find that source. One such energy source is solar energy. We all know that solar energy can be harnessed to generate thermal energy or electrical energy for use in the residential and/or in the commercial applications.  Any material that can store Solar Thermal Energy is called Solar Thermal Fuel (STF).  The quest to harvest solar energy, store the same and use it when needed has been the focus of research in industry and academia alike. For the first time, Professor Grossman’s team at MIT, Cambridge (USA) has come up with a new approach which uses polymer Solar Thermal Fuel (STF) storage platform utilizing STF in its solid-state.  According to the published article, researchers stated, “Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. This approach enables uniform films capable of appreciable heat storage of up to 30 Wh kg?1 and that can withstand temperature of up to 180 °C.”How the STF process works?Certain molecules (chemicals) can have 2 different stable structural forms. These structures are called conformations.  When original molecular conformation is exposed to sunlight, the molecule gets charged and the original conformation changes to the other and stay in that charged conformation for a long period.  The charged molecule snaps back to their original shape (conformation), when triggered by a very specific temperature or other stimulus generating heat in the process. Currently, developed polymeric film can release heat about 10 degree C above the surrounding temperature. Film property improvements are underway. German auto company BMW, has sponsored this research. Where the potential application lies - your guess is as good as mine.References:The Atlantic, p 56, November 2015Zhitomirsky, D., Cho, E. and Grossman, J. C. (2015), Solid-State Solar Thermal Fuels for Heat Release Applications. Adv. Energy Mater., 1502006. doi:10.1002/aenm.201502006...
Reliable and high performance lithium ion batteries commonly known as LIBS are highly sought after product by industries. We all have heard stories about laptops, electric vehicles, airplanes catching fires due to LIBS. Underlying problem is the battery overheating. Preventing batteries from overheating is crucial to the public safety.  Now a team of researchers at Stanford University designed a thermo-responsive (heat sensitive) plastic composite film made from polyethylene and spiky nickel microparticles coated with graphene which shuts down the battery if the temperature is too high.         In a recently published work led by Yi Cui and Zhenan Bao of Stanford University, USA concluded “Safe batteries with this thermoresponsive polymer switching (TRPS) materials show excellent battery performance at normal temperature and shut down rapidly under abnormal conditions, such as overheating and shorting.” How practical this design approach is? Time will tell.References: Y. Cui, Z. Bao et al Nature Energy vol.1, Article number: 15009 (2016); DOI: 10.1038/nenergy.2015.9Chemical & Engineering News, Page 7, January 18, 2016...
In aviation industry, the focus is how to improve fuel safety and handling. Mike Jaffe and Sahitya Allam gave their perspective on safer fuels by integrating polymer theory into design (Science, 350, No. 6256, p. 32, 2015).Mist (generated from the fuel) is much more flammable than the liquid and that is why anti-misting kerosene interferes with mist formation when a low percentage of a polymer is added into it.  The problem however, is that the polymer chain undergoes scission during handling and can’t assist in suppressing mist formation. The answer comes from a recent paper published in the Journal Science by Professor Julia Kornfield and her cross-functional team at Caltech, Pasadena, USA. The group designed a megasupramolecules having polycyclooctadiene backbones and acid or amine end groups (telechelic polymer) which is short enough to resist hydrodynamic chain scission while protecting covalent bonds through reversible linkages. Yes, polymers can be designed to suit our societal needs including aviation fuel safety.Reference: M-H Wei, B. Li, R.L. Ameri David, S.C. Jones, V. Sarohia, J.A. Schmitigal and J.A. Kornfield; Science, 350, (6256), pp. 72-75 (2015)...
At the TED conference, Carbon3D, a Vancouver based company touted a radical 3D printing technology and named it CLIP or Continuous Liquid Interface Product. CLIP grows parts instead of printing them layer by layer. It harnesses light and oxygen to continuously grow objects from a pool of resin.  The result: make commercial quality parts at game-changing speed.  CLIP is 25 to 100 times faster than traditional 3D printing technique.  To make the point, Carbon3D web site provides a head-to-head comparison of CLIP to Polyjet, SLS and SLA.[Press release: March 16, 2015, Vancouver, Canada.  www.carbon3D.com]...
Self-healing plastics has been around for a while. Applications include self-healing medical implants, self-repairing materials for use in airplanes and spacecrafts. Even scientists have made polymeric materials that can repair itself multiple times. A recent report in Science describes a significant advance in self-healing plastics. The authors describe a product that mimics how blood can clot to heal a wound. When the plastic is damaged a pair of pre-polymers in channels combines and rapidly forms a gel, which then hardens over 3 hours.The authors demonstrated that holes up to 8 millimeters wide can be repaired. The repaired parts can absorb 62% of the total energy absorbed by undamaged parts.  Science never stops.Reference:S. R. White, J. S. Moore, N. R. Sottos, B. P. Krull, W. A. Santa Cruz, R. C. R. Gergely; Science, Restoration of Large Damage Volumes in Polymers, Vol. 344 no. 6184 pp. 620-623; (9 May 2014). ...
Knowingly or unknowingly, flexible electronics has become a part of our daily life.  Transparent conductive films (TCFs) are used in mobile phones, tablets, laptops and displays.  Currently, Indium Tin Oxide or commonly known as ITO is the material of choice.  But use of ITO has some major disadvantages and these are brittleness, higher conductivity at greater transparency, and supply of Indium.  This is where non-ITO materials come into play. Based in St. Paul, Minnesota (USA), Cima NaoTech’s uses its SANTETM nanoparticle technology, a silver nanoparticle conductive coating which self-assembles into a random mesh like network when coated onto a flexible substrate such as PET and PC.  According to a recent press release, the company stated SANTETM nanoparticle technology enabled transparent conductors in a multitude markets from large format multi-touch displays to capacitive sensors, transparent and mouldable EMI shielding, transparent heaters, antennas, OLED lighting, electrochromic and other flexible applications.  Cima NanoTech is working with Silicon Integrated Systems Corp. (SIS) of Taiwan and using its highly conductive SANTE FS200TM touch films to develop large format touch screens.References: Press release, San Diego, June 03, 2014; www.cimananotech.com ; http://www.cimananotech.com/sante-technology ; http://www.sis.com/...
In an article appeared today (January 29, 2014) in The Guardian newspaper, Stuart Dredge wrote, “From jet parts to unborn babies, icebergs to crime scenes, dolls to houses: how new technology is shaking up making things”1. Mr. Dredge was speaking about 3D printing technology.  The heart of this technology is the 3D printer itself. Stratasys, a company headquartered in Minneapolis, USA is the manufacturer of 3D printers.  It recently announced the launch of Color Multi-material 3D Printer, the first and only 3D printer to combine colors with multi-material 3D printing.  According to the press release2, by using cyan, magenta, and yellow, multi-material objects can be printed in hundreds of colors.  The technology is based on proven Connex technology.  While the base materials are plastics and elastomers, they can be combined and treated to make finished products of wide ranging flexibility and rigidity, transparency and opacity.  Designers, engineers and manufacturers can create models, mold, and parts that match the characteristics of the finished production part. This includes achieving excellent mechanical properties.  According to the manufacturer, print job in the newly revealed printer can run with about 30 kg of resin per cycle and prints as fine as 16 micron layers for models.  No wonder why some call the new Color Multi-material 3D printer a groundbreaking stuff.References: 1. www.theguardian.com.technology/2014/jan/29/3d-printing-limbs-cars-selfies (January 29, 2014)2. http://investors.stratasys.com/releasedetail.cfm?ReleaseID=821134 (August 3, 2014)...
Instead of stitches or skin staples, doctors use skin glue to close wounds. The glue joinsthe edges of a wound together while the wounds heal underneath. Most of the timeskin glue is used for simple cuts or wounds. According to the paper published inScience Translational Medicine, there are no clinically approved surgical glues thatare non-toxic, bind strongly to tissue, and work well in wet and highly dynamicenvironments within the body. This is the reason why this published work is promisingwhere infants born with heart defects would benefit tremendously. Researchers at the Brigham and Women’s hospital in Boston have engineered ‘bio-inspired’ gluethat can bind strongly to tissues on demand, and work well in the presence ofactively contracting tissues and blood flow. The authors of the paper show howthe glue can effectively be used to repair defects of the heart and blood vessels during minimally invasive procedures. [References: P. J. del Nido et al; Sci. Transl. Med., DOI: 10.1126/scitranslmed.3006557; See also, www.geckobiomedical.com/news/gecko-biomedicals-co-founde.html]...
Stability of organic electronics in water is a major research challenge. For this reason,organic electronics has yet to see any sensing application in aqueous environment.However, as understanding of underlying mechanism of stability aspect is becomingclearer, new developmental efforts to make water compatible organic polymer devicesare taking place. Recently, Professor Zhenan Bao’s group in the department of chemical engineering at Stanforduniversity revealed in a paper published in the journal of Nature Communications thatsolution- processable organic polymer could be stable under both in freshwater andin seawater. Developed organic field-effect transistor sensor is able to detect mercury ionsin the marine environment (high salt environment). Researchers believe that the work hasthe potential to develop inexpensive, ink-jet printed, and large-scale environmental monitoring devices. [References: O. Knopfmacher, M.L. Hammock, A.L. Appleton, G. Schwartz, J. Mei, T. Lei, J. Pei,and Z. Bao; Nature Communications, 5, 2954, January 6, 2014; DOI: 10.1038/ncomms3954]...
Insulin, the wonder medicine for diabetes was discovered about a century ago.Since insulin does not get into the blood stream easily, diabetes patients oftenhave injected themselves with insulin. Now a group of scientists led by Dr. Sanyog Jainat the Center for Pharmaceutical Nanotechnology of National Institute of Pharmaceutical Education and Research in Punjab, India has designed a polymerbased package for oral insulin administration. The package design addresses two major obstacles, 1) digestive enzymes must notdegrade insulin prior to its action and 2) the insulin gets into the blood stream.The package contained folic acid functionalized insulin loaded in liposomes.To protect the liposomes (lipids or fat molecules) they were alternately coated withnegatively charged polyacrylic acid (PAA), and positively charged poly allylamine hydrochloride. Studies were conducted to compare the efficacy of bothdelivery systems: designed polyelectrolyte based insulin and standard insulinsolution. Effects of oral administration lasted longer than that of injectedinsulin, authors reported in a recent article in Biomacromolecules. [Reference: A.K. Agarwal, H. Harde, K. Thanki, and S. Jain; Biomacrmolecules, Nov. 27, 2013;DOI: 10.1021/bm401580k]...
Research in the area of stretchable electronics is heating up!  Thanks to polymers. Led by Professor George M. Whitesides of Harvard University (USA), a team of researchers have demonstrated in a recently published paper in Science that ionic conductors can be used in devices requiring voltages and frequencies much higher than commonly associated with devices using ionic conductors.  The team showed for the first time that electrical charges carried by ions and not electrons, can be utilized in fast-moving, high voltage devices.As a proof of concept, the authors of the study built a transparent loudspeaker that produces sound across the full audible range i.e., 20 Hz to 20 kHz.  Components [such as VHB 4910 tape (acrylic tape with PE liner), polyacrylamide hydrogel containing NaCl electrolyte] used for the high speed, transparent actuators are described in the paper.Tissues and cells are soft and require stretchable conductors for biological systems. Many hydrogels are biocompatible which makes this work particularly an important one. The design of gel-based ionic conductors is highly stretchable, completely transparent and offer new opportunities for designers of soft machines.   [Reference: C.Keplinger, J-Y. Sun, C.C. Foo, P. Rothemund, G.M. Whitesides, and Z. Suo; Science, 341 (6149), pp. 984-987 (2013); DOI: 10.1126/science.1240228]...
Interweaving biological tissue with functional electronics, one can make bionic ears.  NASA has tested 3D-printed rocket engine part.  Then why not 3D print yourself?Well, Twinkind, a German start-up company is now offering enthusiasts statues of themselves for display.  How this works?  A full body scanner takes an image of the customer’s body, transfers the file to the printer after which 3D printer laser sinters a composite powder layer by layer into the customer image.Can we dare to say that Madame Tussauds wax figure of Voltaire can now be 3D printed in polymers soon!  [Reference: www.twinkind.com ]...
Polymer membranes have become a leading contender in numerous separation processes.  Be it in gas (air, hydrogen etc.) or be it in water purifications (salinated water, waste water etc.).  Not only polymer membrane technology helps reducing the environmental impact but also it is cost-effective.  Fracking in shell gas is one of many examples. New advances in drilling technology (such as horizontal drilling) have led to new hydraulic fractures called fracking.  Hydraulic fracturing requires about 2.5 to 5 million gallons of water per well.  Water management and its disposal are major costs for producers.One major challenge, however, of the membrane technology is the fouling (damage caused by contaminants) mitigation.  This has been recently studied by a group of researchers from University of Texas at Austin led by Professor Benny Freeman to address efficiency and reuse of water for fracking in shale gas plays.Researchers modified polydopamine coated UF (ultrafiltration) module by grafting polyethylene glycol brushes onto it.  The result is more hydrophilic surfaces which in turn improved cleaning efficiency relative to unmodified modules. The coating improves the membrane life, and can easily be applied to membrane surface by rinsing it through the recycling system.[References: D.J. Miller, X. Huang, H. Li, S. Kasemset, A. Lee, D. Agnihotri, T. Hayes, D.R. Paul, and B. Freeman; J. Membrane Sci., 437, pp. 265-275 (2013); Also see www.advancedhydro.net ]...
Flexible electronics can change the way we use electronic devices.  It is a term used for assembling electronic circuits by mounting electronic devices on a flexible plastic. A recent review article captured the advancement of CNT and graphene based flexible thin film transistors from material preparation, device fabrication to transistor performance control compared to traditional rigid silicon1. Silicon is used almost exclusively in electronic devices.Now Prof. Ali Javey led a team at the University of California, Berkley to develop a printing process to make nanotube transistors at room temperature with gravure printer.  The plastics used is polyethylene terephthalate (PET). The device exhibited excellent performance with mobility and on/off current ratio of up to ~9 cm2/ (V s) and 105 respectively.  Also, maximum bendability is observed.  The paper authors conclude that this high-throughput printing process serves as enabling nanomanufacturing scheme for range of large-area electronic applications based on nanotube networks2. References:1. D-M. Sun, C. Liu, W-C. Ren and H-M Cheng; Small, DOI: 10.1002/smll.2012031542. P.H. Lau, K. Takei, C. Wang, Y. Zu, J. Kim, Z. Yu, T. Takahashi, G. Cho, and Ali Javey; Nano Letters, 13 (8), pp. 3864-3869 (2013); DOI. 10.1021/nl401934a...
Drinking coffee from paper cups are as common as drinking water from plastics bottle. The issue however, is recycling of disposable cups. The disposable cups are made up of 90-95% of high strength paper (fibers) with a 5% thin coating of plastic (PE).To address the recycling issue, James Cropper Speciality Papers of UK have developed a process which involves softening the cup waste, and separating the plastic coating from the fiber.  After skimming off the plastic, remains are pulverised and recycled, leaving water and pulp behind.  According to the company news release, the high grade pulp is reused in luxury papers and packaging materials.An innovative approach to address a common problem.[Reference: www.jamescropper.com/news ]...
A search for an alternative to rigid silicon wafers gave birth to the area of flexible or bendable electronics. Research has been intense for the past few years in the area flexible electronics as it opens up multitude of new applications. Polymers play an important role to exciting field of flexible electronics.In a recent research report, a team of scientist led by Prof. Ali Javey of University of California, Berkeley (USA)  has shown for the first time user-interactive electronic skin or e-skin can conformally wrap irregular surfaces and spatially map and quantify various stimuli through a built-in active matrix OLED display.  Three electronic components namely thin film transistor (uniform carbon nanotube based), pressure sensor, and OLED arrays (red, green, and blue) are integrated over a plastic substrate.  Spin coated and cured polyimide on a silicon wafer is used as the flexible substrate.  Details are in the paper.This work essentially provides a technology platform where integration of several components (organic and inorganic) can be done at a system level on plastic substrates. According to the paper, this e-skin technology could find applications in interactive input/control devices, smart wallpapers, robotics, and medical/health monitoring devices.    [Ref: C. Wang, D. Hwang, Z. Yu, K. Takei, J. Park, T. Chen, B. Ma, and Ali Javey; Nature Materials, Published online July 21, 2013; DOI: 10.1038/NMAT3711]...
Recent buzz in the technology world is 3D printing.  Researchers to designers are creating new products everyday using 3D printing technology.  Even eBay has unveiled its services to those looking to make their own creations using 3D printing App.Since ages composites have played a crucial role in our society. Inspired by natural (biological) composites such as bone or nacreous abalone shell, researchers from MIT (USA) and Stratasys have developed composite materials that have fracture behaviour similar to bones.  Using computer model with soft and stiff polymers, the team has come up with a specific topological arrangements (hierarchical structures) of polymer phases to boost the mechanical behaviour in the composites.Interestingly, the team has been able to manufacture (thanks to 3D printing) a composite material that is more than 20 times larger than its strongest constituent.  The referenced paper showed that one can use computer model to design composite materials of their choice, tailor the fracture pattern and then use 3D printing technology to manufacture the composites.[Ref: L.S. Dimas, G.H. Bratzel, I. Eylon, and M.J. Buehler; Advanced Functional Materials, Published online June 17, 2013; DOI: 10.1002/adfm.201300215]...

3dprinting_anubis_figure1The present pace of technological advancement is fast and furious.  It is becoming harder than ever  to predict what will come next. When Stratasys announced1 that it had produced world’s first color multi-material 3D printer, the race for faster new product design began.  It has the ability to produce anything regardless of the complexity of the shape and color. Call it hype or not, the 3D printing technology is already in the spotlight and is undoubtedly an important fabrication technology (Figure: Gear wheel; Courtsey of Anubis3D).   The incredible range of potential consumer applications that this game changing technology is starting to provide has caught the eye of the general press, for example Stuart Dredge2 wrote an article for the Guardian newspaper that starts “from jet parts to unborn babies, icebergs to crime scenes, dolls to houses: how new technology is shaking up making things.”

This review article provides answers to the general questions that might occur to users of 3D printing technology, it points the reader to some of the excellent articles about various aspects of the topic, provides a glimpse of the current trends and discusses the limitations of the technology and their impact on its future prospects.

How did it all begin?

The idea of printing 3D objects was born in the ‘80s, when Chuck Hull of 3D Systems conceptualized and patented the idea which he used to found 3D Systems in 19863.  3D technology is based on stereolithography (STL). Mr. Hull recognised how uv light might be used to solidify layers of molten plastic into whatever shape he liked and then combine these layers to make a 3D product.  The New York Times article4 “Who made that 3D printer” gives a lucid picture of how 3D printer evolved.  Early research at MIT was focused on rapid tooling using metals and ceramics5,6. It took another decade to commercialise rapid prototyping.

Are there different ways to print 3D objects?

In an attempt to classify 3D printing processes, ASTM International (ormerly known as American Society for Testing and Materials) identified seven distinct additive manufacturing processes7. These are all based on the same principles as ink jet printing, which creates a digital image by shooting ink droplets onto a sheet of paper, a plastic object a textile or other more exotic substrates.  3D printing provides complex shapes by replacing the ink with droplets of plastics or metal those are used to construct 3-dimensional objects by adding layer upon layer of material.  This allows the construction of customized objects without making expensive moulds.
 
In a manufacturing context this technique is called Additive Manufacturing. To print a 3D object, virtual models from CAD or other modeling software are taken and layered into digital cross-sections, which the 3D printer uses as a guideline for printing successive layers.  This approach uses materials more efficiently than traditional manufacturing techniques (such as cutting or drilling) since excess material is not needed.   The quality of the final print and the object and print speed depend on the printer type and model. 3D printing can be used in applications such as industrial design, automotive, aerospace, medical, fashion, footwear, eyewear, food and others.  Cheaper machines can be used to produce prototypes, while machines that make production grade products tend to be much more expensive.

There are several ways that a printer can create the individual 2D layers from a design and combine them to produce the final 3D object.  In the first approach to 3D printing (Stereolithography as patented by Chuck Hull of 3D Systems in 19848), liquid materials (photopolymer resins) are cured on an elevator platform with a UV laser shone onto it. Stereo lithography needs a supporting structure to attach the part to the elevator platform.  Supports have to be removed after the build is complete. 

Stereolithography is a versatile process where different materials can be combined in one product. An example of multi-material stereolithography is shown in the picture rook.  The rook displayed here was fabricated using the stereolithography additive manufacturing process with three photopolymers and four build phases8a: 1) construction of outer structure using Somos®WaterShedTM11120, 2) construction of staircase using Somos®ProtoThermTM12120 in red, 3) construction of white double spiral using Somos®14120 White, and 4) construction of top structure using Somos®WaterShedTM11120.3dprinting_rook3_figure_7

Selective laser-sintering (SLS) is a widely used method for making plastic parts, in which layers of powdered plastic or metal are selectively hardened (sintered) with a moving laser or electron beam and the remaining, material removed. The SLS process typically uses a carbon dioxide laser which traces the required shape directly in a compacted powder bed of material from a 3D CAD model via an STL computer file.  As each layer of powder is fused (sintered) by the laser to form the necessary shape, next layer of powder is introduced to the laser and gets sintered and adhered to the previous layer. SLS makes little waste and unused raw material could be recycled. The method is known for the quality, reproducibility and the strong plastic parts that result.  SLS is the most accurate additive manufacturing process and is used to build prototypes and for small batch production.  Aerospace industries such as Boeing have exploited this method extensively to make various non-structural parts.  The method can also be used to repair worn parts, such a turbine blades9.3dprinting_anubis_figure21 

Fused deposition modeling (FDM)10 is another commonly used process, commercialized by Stratasys in 1990. Virgin resin, filament wound on a coil, is unreeled to feed material to an extrusion nozzle head. Objects are built by melting these plastic filaments and extruding them along computer-controlled paths.  FDM is used to make product development prototype parts because of its robustness.  It is often used in small 3D printers for hobbyists. However, the surface finish looks porous.
 
In a recently published report, Gridlogics Technologies categorized and graphically analyzed trends, processes, and applications of 3D printing technologies11.  Inquisitive readers can also read more about practical advantages and drawbacks of all the layering processes at the anubis3d website12.  More background and historical references are available in Wikipedia13.

Which Plastic can be used for 3D printing?

Plastics engineers can make objects of their choice polymers that range from thermoplastics to thermosets to TPEs.  Photopolymers and epoxy resins can also be used for stereolithogrphy.   For SLS, nylon powders (PA11 and PA 12) predominate.  Nylons can be filled with glass, aluminum or  carbon fiber. They can also be impact-modified or modified with flame retardants. 

Late last year Solvay unveiled new materials (Sinterline PA6 powders) which expanded the capability of 3D printing to make end-use nylon parts for automotive injection moulding14. Highly engineered PEEK and PEI are also available for SLS. For thin walled parts, Stratasys has developed a new ABS material (ABS2) for its Polyjet 3D printer.  Styrolution provides styrenic polymers for 3D printing industries. Bayer Materials Science now has Desmosint X 92A-1, a TPU with high elasticity, tear strength and abrasion resistance.  Microfol Compounding GmbH is offering PP (SinterPlast PP) for laser sintering. These and other plastic materials designed for use in 3D printing are reviewed in a recent article15.

What can 3D printing do?

The technology empowers entrepreneurs to design innovative products and test concepts without the investment of a great deal of time and money since a good knowledge of machinery or skills are not required to convert ideas into a concrete product with 3D printer.   For example the Stratasys Objet500 Connex3 Color Multi-material 3D Printer is claimed to enable designers, engineers, and manufacturers to develop models, molds, and parts which match the characteristics of production parts meeting  mechanical property requirements such as tensile strength, elongation at break and hardness16.3dprinting_connex3_figure4

Ford engineers use industrial-grade 3-D printing machines that cost as much as $1-million to produce prototypes of cylinder heads, brake rotors, and rear axles for test vehicles. These are produced in less time than that required with traditional manufacturing methods. These engineers reduced the production time by about a month for the EcoBoost family of engines by using 3D printing to create a casting for a prototype cylinder head. This complex part included numerous ports, ducts, passages and valves to manage fuel and air flow. The traditional casting method can take four to five months since it involves designing a sand mold as well as the tool to cut the mold. With 3-D printing, engineers can design and print the sand mold and pour the metal in three months17.

A Stratasys case study18 describes how  KOR EcoLogic used Fused deposition modeling (FDM) to build a car body (see Figure below on the right).  How did FDM compare to traditional prototyping methods?3dprinting_urbee_figure5  A comparative analysis showed that cost and lead time for the FDM process was lower than the traditional method using FRP or fiberglass.

Magnetometer is known to measure the strength and/or the direction of the magnetic field at a point of space. It has numerous applications from measuring earth's magnetic field to tactical military technology.   The magnetometer displayed in the figure (photo below: left) contains a microprocessor and three Hall effect sensors placed in orthogonal planes to detect magnitude and direction of a magnetic field.  The circuit interconnects were direct printed onto a stereolithography manufactured outer shell18a.

At the W.M. Keck Center for 3D Innovation,University of Texas at El Paso, Professor Ryan Wicker's group is actively pushing the boundaries of Additive Manufacturing technologies. The group recently built a novelty six-sided gaming die via stereolithography and direct write of conductive ink traces with manual placement of electronic components (photo below: right).  A microprocessor and accelerometer work in unison so that upon halting, the top surface is identified and light-emitting diodes (LEDs) are illuminated. A USB port allows recharging of a lithium polymer battery, enhancing user interface18b.3dprinting_magneto_figure11 
      

In bio-medical field, when 3D printing technology is used to fabricate scaffolds, the additive process must be chosen with care, since each method has its own merits and drawbacks.  Given the fact that interconnected pores can be created with controlled structures, rapid prototyping for bone scaffold fabrication is an active area of research.  Scaffold fabrication, however depends on the types of additive process used.  This application is well summarized in a recent review19.

Microfluidic chips are used for applications such as point-of-care diagnostics and environmental monitoring.  Shallan et al recently reported that microfluidic chips could be made quickly and at low cost.  Fabricated chips that are transparent and which have smaller channel sizes can be made using a consumer level 3D printer19a. These are examples of the numerous application areas where 3D printing can have huge impact on new products manufacturing.3dprinting_die_figure10 

What are the limits to 3D printing today?

It is debatable whether or not 3D printing can replace high volume manufacturing techniques such as moulding, which easily spit out products by the minute.

Constraints currently include manufacturing speed and cost.

3D printers are slow especially for large products. The process can be further slowed because models don’t always scan well.

At present the costs for the printers, the software and the materials means that the cost to make 3D printed products is  much higher than the price for which these goods are sold. Laseter and Hutchison-Krupat20 wrote, “It’s a stretch to envision a near term future in which 3D printer at home to make a fork or a chess piece”.

Raw material costs are high because material volume dictates the price. An injection molding grade of ABS in bulk costs anything between $2 and $3 per kilo whereas a bespoke powder or filament of ABS for 3D printing could cost as much as $70 - $80 per kilo.

The range of materials currently available for 3D printing compared to traditional molding process is limited. There is a question as whether a 3D printer can be made to work with the range of grades used in traditional manufacturing.  There are millions of molded and extruded plastics products in the market and these are made from thousands of different plastics including amorphous, semi-crystalline, and crystalline materials. Whereas plastics used for 3D printing need to have certain properties such as melt index or viscosity which allows them to be pass through an ink-jet nozzle and set quickly.

Metal-plastic hybrid is another area of commercial interest.  Current 3D printers do not have the ability to print metal-plastic hybrid objects.  Ability to print only to a few types of metal alloys limits the technology.

The size of objects that can be printed provides a further limitation, although the Dutch government is supporting an interesting project, the goal of which is to use 3D printing to build a house21.

Concerns have been expressed about limitations in mechanical strength and whether the plastics layers have sufficient adhesion so that they do not delaminate in the z- direction21a.  There are also issues with certain angles of printer head, surface finish, post-processing, and availability of appropriate 3D model libraries.

As a result of the current limitations, the notion of 3D printing technology bringing any kind of industrial revolution is arguable. The answer to the question 'Can 3D printing be labeled as a disruptive manufacturing technology?' depends on who you ask!  Nevertheless, certain application areas will see a major shift towards 3D printing as manufacturing cost becomes lower and where more complex parts can be made than with traditional methods.

Are there any commercial applications yet?

Despite the current limitations, 3D printing has a tremendous future.  The examples such as those we describe below in areas as diverse as aerospace and healthcare those have created huge expectations in this technology.

Companies such as Stratasys (SYS), 3D Systems (DDD), Voxeljet AG (VJET), Hewlett-Packard (HPQ), Hitachi Chem Co. Ltd. (HCHMY), IBM Corporation (IBM),  are publicly traded and are at the forefront of the 3D printing business.  Reference 11 provided a current list of 20 major companies in the world who are actively pursuing the technology. Recently, first of its kind a mutual fund has been touted that consists of 3D printing businesses only. The name of the fund is 3D printing and Technology Fund.  Articles22, 22a in Bloomberg Business Week and CNN Money are for those who are interested in knowing more about these companies.

BAE Systems engineers are using 3D printed metal components in its Tornado GR4 aircraft.  Use of 3D printed component could save the Royal Air Force £1.2 million in maintenance and service cost over the next 4 years22bMorris Technologies (now part of GE) was well known for its additive manufacturing services to industries including lightweight parts for unmanned aerial vehicles. GE plans to 3D print tens of thousands of parts for its jet engines alone.  NASA has announced that that it has successfully tested a 3D printed rocket engine part.  It is also preparing to launch a 3D printer into space so that the printer could make spare parts on the fly to avoid carrying large loads of spares with them.  A typical F-18 fighter jet likely to contain 90 3D printed parts although has been in service for 2 decades.  On a less romantic note, aircraft such as MD-80 jets, which ceased its production long ago, have leaking toilets for which it is difficult to find spare parts. Its new plumbing is now being 3D printed in an aerospace grade plastic23.
 
Robots are part of automation in the plastics industry.  Often mechanical grippers are used to pick-up, transport, and lay down machine parts on a production line.  Wittman Robot Systeme had a gripper consisting of 21 different components made of aluminum, rubber and plastics.  Kuhn-Stoff Gmbh & Co, a German designer founded in 2005 simplified the gripper design by using EOS’s FORMIGA P 100 3D printer with only 2 different plastic components weighing 86% lighter than the original gripper24

The health-care industry is an early adopter of the 3D printing technology despite stringent bio-compatibility standards . Millions of hearing-aid shells from scans of patients’ ear canals to straightening teeth using transparent plastic “aligners” are in use25Oxford Performance Materials in Connecticut (USA) has developed FDA approved OsteoFabTM from PEEK polymer.  OsteoFabTM can be used to replace bone damaged by disease or trauma.  In one case it has been reported that a man has had 75% of his skull replaced with a custom made 3D printed implant26.  3D printed low cost prosthetic limbs for amputees are another exciting area. Not Impossible Labs27 is tackling the healthcare challenges in poorer countries with low cost low cost prosthetic limbs, made with  consumer grade 3D printers operating with open-source software.
     
Synthetic organ technology could help to remove an important  medical need by reducing the long transplant waiting list for vital organs.  The main problem is to make thicker and more complex tissues having blood vessels.  Harvard university researchers created a tissue containing skin cells and biological structural material interwoven with blood-vessel like structures. The tissue is touted as the first 3D printed material that includes potentially functional blood vessels28.
 
Different colour products for consumers' use can be manufactured and Stratasys has shown by printing numerous product items such as cyan glasses, multi-colour bi-cycle helmet etc.3dprintingcyanglasses_figure6        3dprinting_figure8      3dprinting_sculpteo_figure31

There are also more whimsical applications created by hobbyists and entrepreneurs.  In one example a full body scanner takes an image of the customer’s body, transfers the file to a printer, which is used to produce  statues for display.  Twinkind, a German startup  has used SLS process  to create figurines29.  In another, enthusiasts are developing techniques to use 3D print technology to automate tattooing30.

Which applications can we expect soon?

The following recent advancements promise applications in the near future.:

  •  The Technology Partnership (TTP) claims to have developed multi-material jetting head (Vista 3D) that could print multiple materials including metals, plastics, ceramics, enzymes, and biological cells31.
  • Arburg, an injection moulding machinery maker unveiled at K2013 “freeformer”, a new 3D printing system that work with the same resin as those used in conventional injection moulding machine.  The novelty is not only that standard polymer resin can be used but also the system allows parts to be moulded in two materials or colours.
  • EnvisionTEC’s commercialized 3SP (scan, spin and selectively photocure) process that touts high speed without losing accuracy or resolution regardless of the geometric complexity.
  • EOS GmbH’s PrimePartPLUS can use more recycled materials. It needs only 35% virgin powder.   
  • A collaborative team (Marcelo Coelho and Skylar Tibbits) at MIT is developing Hyperform which can make large part irrespective of a printer’s bed size in small volumes.  The concept stems from when Skylar Tibbits of MIT unveiled in his TED2013 talk how chunks of 3D printed parts intelligently arrange themselves into any object32.  This development gave birth to the concept of 4D printingUniversity of Colorado, Boulder researchers showed a 4D printing process where shape memory polymer fibers could fold, stretch, curl or twist when allowed the environmental exposure changes33 (water, heat or pressure).   
  • Harvard researchers reported in a recently concluded American Chemical Society (ACS 2014) meeting that they have created a printed tissue that mimics natural heart muscles. 

How fast is the industry expected to grow?

According to the Freedonia Group study34, world demand for 3D printing is projected to rise to US $5 billion by 2017.  Although plastics will continue to be important, the use of metals for 3D is expected to grow faster.  Fastest growth is also expected for medical and dental applications.  Specific opportunities are expected in dental applications for braces, crowns, bridges, aligners and models for dental restorations. The aerospace markets expected to see above average growth.
 
The USA will account for 42% of the global sales in 2017.  It has been reported34a that China has committed almost $500 million to establish 10 national 3D printing development institutes and this is expected to result in rapid growth.

Wohlers Associates Inc. has predicted that the global revenues from 3D printers would reach US $3.7 billion by 2015, $6 billion by 2017, and $10.8 billion by 2021.  It also reports that the growth in the low cost (under $5000) “personal” 3D printer market segment is slowing down.  This segment consists of hobbyists, do-it-yourselfers, engineering students, and educational institutions. Wohlers Report 201335 provides an overview and analysis of additive manufacturing and 3D printing worldwide.

A recently published report by IDTechEx36 gave a detailed account of pricing, properties and projections for materials including photopolymers, thermoplastics and powders. According to the report, the market for photopolymers will retain the largest single segment of the market until 2025.  An earlier report by IDTechEx discussed several 3D printing technologies and on-going technological advances along with current and future markets for 3D printing.

What technological advancement is needed to unlock the potential?

The market for prototypes produced with 3D printing is expected to grow tremendously.  Larger printers will be built to address the need of making bigger parts.

3D printing promises to help people develop design gift ideas and print these.  These same printers might be used to print spare parts and other useful household items (see figure of hand held blender). However the question as to whether a 3D printer will become an indispensable household tool is debatable.3dprinting_blender_figure9 The cost of 3D printers will have to drop and more open sourced 3D modeling software must becomes freely available. In addition Killer Applications will have to be developed to catch the imagination of consumers. 

Both hardware and software will see improvements.  3D Printers will continue to become more sophisticated. Multiple types of polymers such as ABS, PLA, nylons will be used to make the different products with the same printer.  Printers might even be developed that will print with either metals or plastics.  Further improvement is required  in many areas including speed, resolution and  tolerances, surface finish and dimensional stability (warpage and shrinkage).
 
Techniques to recycle 3D printed objects will be needed before 3D printer can be considered for commodity items.   This will require work to maintain the quality of 3D printed parts containing regrind.

Printing a large object faster will become a hot area. Collaborations between research institute and industry will increase. Joint work has already begun with Oak Ridge National Laboratory (ORNL) and the Cincinnati Incorporated, a machine tool manufacturer37

There is a need to print 3D ‘on demand’ spare parts for automotive and medical applications, to avoid the need for wait time and to maintain inventory. 

Manufacturing cells for use in patients or to try new drugs in different types of tissues for screening application will see major interest.  Already University of Toronto researchers in collaboration with Sunnybrook Hospital are exploring the possibility of printing soft tissues such as skin to treat burned patients. The challenges that exist in using 3D printing for bone tissue engineering will be the next frontier of research in this area as researchers start to find ways to deal with the post- processing shrinkage, such as  the non-uniform shrinkage that can occur during the  sintering of  porous scaffolds, which can cause parts to crack.  Techniques are also needed to keep minimum distance between pores in a highly porous scaffold with a sintered pore size below 300 microns. 

Final thoughts

As the reader will appreciate, 3D printing provides a lot of promise. Barriers have been identified, but ways around these obstacles are being found at a rapid rate. At this point no one can predict the results of this game changing approach to manufacturing. Even if economics prevents its application to commodity manufacturing, it will serve an extremely important niche in this competitive market environment.

Acknowledgements

The authors would like to thank Professor Ryan Wicker, and companies Stratasys, Anubis3D, and Sculpteo for their assistance in providing the photographs for use in this article.

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