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CHAPTER 1
An Introduction to 3D Printing
This chapter will introduce you to the most commonly used 3D printing techniques applied within the chemical sciences, specifically fused deposition modelling, stereolithography, inkjet printing, selective laser sintering, and selective laser melting. It also includes a brief discussion on the relatively short history and exploding popularity of 3D printing. Within the chemical sciences, fused deposition modelling is the most commonly used printing technique, primarily due to the low cost, an ever increasing range of print materials, and ease of use. Stereolithography would appear currently to be more capable in applications that require high-definition printing, and inkjet printing is suitable for the most complex architectures. Selective laser melting can be applied to print with metals, and selective laser sintering, a closely related technology, with a wide variety of materials. The application and development of 3D printing within the chemical sciences has increased exponentially over the last few years. The 3D printer market as a whole is projected to grow to $33.6 billion by 2022, representing a staggering rate of growth for what has emerged as an entirely new industry in itself. As President Barak Obama stated in his 2013 State of the Union address, “3D printing has the potential to revolutionize the way we make almost everything”, and based upon the uptake of this technology within the chemical sciences, it would appear that chemists are certainly leading this revolution by example.
1.1 History
It is certainly true to say that the history of additive fabrication technology, now commonly referred to as 3D printing, is rather complex to unravel. The precise definition of what constitutes 3D printing has much to do with this confusion, and so to begin this book we must present our concise definition, upon which we make all our observations and comments from this point forward. Techniques which fall under our definition of 3D printing include all production technologies that are based upon the automated and computer-controlled formation of three-dimensional objects from one or more starting materials, either liquid or solid, through an additive process based upon solidification. If we apply this definition, we can take the origin of 3D printing back beyond the common claims of an early 1980s origin, and step back to 1977, when Swainson and Kremer patented their proposed scheme for the creation of ‘Three dimensional systems’. This was based upon the exposure of reactive monomer systems to the intersection of radiation beams, which following a direct or indirect polymerisation process, produced a sensible 3D object or solid structure. 1 A few years later in 1980, Hideo Kodama filed a patent application for a 3D printing process (for rapid prototyping), which was followed by a research article in 1981, detailing the work, entitled ‘Automatic method for fabricating a three-dimensional plastic model with photo hardening polymer’. 2 The approach utilised a commercial liquid photo-hardening polymer known at the time as ‘Tevista’ (from Teijin Ltd.), which was a mixture of unsaturated polyester, acrylic ester, and styrene monomer cross-linkers, a polymerisation initiator, and a UV sensitiser. A xenon lamp and optical fibre coupled to a moving x/y plotter were the other essential elements to these very early 3D printers (Figure 1.1). However, the patent application by Kodama did not progress to a full patent, as the author failed to file the full patent application before the one-year deadline. Despite this, the published paper confirms this historical contribution and marks the beginning of an exponential growth in the field.
Figure 1.1 Schematics of the 3D printers that were presented by Hideo Kodama: (a) build plate is moving into the liquid resin, (b) build plate is moving away from the liquid resin, and (c) raster with an optical fibre. 1 – ultraviolet rays, 2 – mask, 3 – solidified layers, 4 – liquid photo-hardening polymer, 5 – movable plate, 6 – receptacle, 7 – shutter, 8 – optical fibre, 9 – XY plotter, and 10 – optical lens. Reproduced from ref. 2 with the permission of AIP Publishing.
Only a few years after Kodama's work, in 1983, Charles (Chuck) Hull, who is widely regarded (particularly in North America) as the father of 3D printing, invented a stereolithographic apparatus (SLA), and subsequently secured a patent on the technology in 1986. 3 The development of this first stereolithography based printer marked the beginning of commercial 3D printing technology, and rightly earned Hull a place in the National Inventors Hall of Fame on May 21st, 2014.
The company ‘3D Systems’ introduced the first commercial SLA (SLA-1) 3D printer in 1987, which began selling in 1988 after rigorous testing. This was the spark that ignited the fire, which throughout the 1990s saw several pioneers and their new alternative additive manufacturing processes developed, patented, and commercialised. These included Scott Crump, who patented fused deposition modelling (FDM) in 1992, 4 Deckard, Beaman, and Darrah, who together patented their technology for selective laser sintering (SLS) in 1992, 5 Sachs, Haggerty, Cima, and Williams, whose 1993 patent ‘three-dimensional printing’ formed the basis of what is now commonly referred to as ‘3D inkjet printing’, 6 and finally, Feygin, Shkolnik, Diamond, and Dvorskiy, who patented laminated object manufacturing (LOM) in 1998. 7 SLA-1 earned recognition as an American Society of Mechanical Engineers Historic Mechanical Engineering Landmark (Figure 1.2), and the award citation read; “This is the first 3D printer manufactured for commercial sale and use. This system pioneered the rapid development of additive manufacturing. A method in which material is added layer-by-layer to form a solid object, as opposed to traditional manufacturing in which material is cut or machined away. The SLA-1 is based on stereolithography, using a precisely controlled beam of ultraviolet light to solidify liquid polymers one layer at a time. Charles Hull developed stereolithography in 1983 and formed 3D Systems to manufacture and market a commercial printer. 3D printers based on Hull's design are now widely used to make complex components in a wide variety of materials.”
Figure 1.2 (a) SLA-1 printer and (b) its enrolment as a historic mechanical engineering landmark.
Throughout the 1990s and 2000s, additive manufacturing gained its foothold as an attractive alternative to traditional manufacturing processes, and so quickly began to impact a wide spectrum of industrial, scientific, educational, and social activities. This gave birth to various new terms for much the same thing, such as rapid prototyping, rapid tooling, rapid casting, and rapid manufacturing. However, in 1993, Sachs et al. at the Massachusetts Institute of Technology, coined the term ‘three-dimensional printing’ and trademarked 3DP™, which was readily embraced globally as an umbrella term for all similar additive manufacturing processes, regardless of the field.
The full range of commercial 3D printers can be roughly divided into two major groupings. The first gro...
