The history of 3D printing is short but impactful. Only a handful of years ago, few would have heard the term 3D Printing. In fact, the term hardly seems to make sense. Printing means creating text and images on flat paper with ink, right?
Yet today, 3D Printing not only exists but is beginning to drive important advances in everything from automobile manufacturing to human prosthetics. This article takes a look at 3D Printing: what it is, what it is doing and where we are headed.
Quick History of Computer Printing
Printing was essential for the earliest computers since most computer jobs consisted of submitting programs and data, usually in the form of punched cards, and receiving output printed on paper. In very early computing environments, printed output was obtained using teletype machines. These were basically automated typewriters, printing a single character at a time as the printing mechanism moved across each line.
Printers for large mainframe computers needed to be much faster. They occupied large cabinets and printed a complete line of text at once on extra wide paper. These were known as line printers.
Both of these early printer types used fixed metal type characters, as in book printing, striking a moving ribbon of ink to form characters on paper. Since the characters were fixed, there was only one typeface and one size of type, again just like typewriters.
For smaller and cheaper computing environments, a new model was developed, in which each character was formed by a series of dots. These dot matrix printers used tiny pins stacked vertically to create images of a broader variety of characters and graphics. Early models used 7 pins to build a 5 by 7 matrix for each character. Later models used as many as 24 pins.
An alternative technology sometimes used was electrostatic imaging. This approach, found in many photocopiers, creates charges on the surface of special paper. These charges then attract ink. Another method that has seen some use is thermal imaging, in which small areas of special paper are heated, causing the paper to darken.
In recent years, however, two alternative printing technologies first developed in the 1970s have become the dominant choices for mainstream computing applications.
Laser printing, an evolution of electrostatic printing, is now widely used. This technology uses a laser beam to generate charges on a rotating drum. The drum then attracts particles of ink in a powder form onto a paper surface. Laser printing is relatively expensive, though it has become much more affordable in the last decade. It is suitable for fast, high volume printing, and has become the technology of choice in business and professional environments.
The other technology that has become very important is inkjet printing. In this approach, droplets of liquid ink are directed onto paper through tiny orifices in a print cartridge. Selective generation, or electrostatic deflection, are used to position each droplet as desired.
Inkjet printing has a number of important advantages:
- It is very inexpensive (inkjet printers start at prices well under $100)
- It can produce full-color images by providing ink cartridges in the primary colors
- It can produce higher resolution images than impact technologies, though not as high as laser printing.
Typical inkjet printers offer moderate speed and moderate resolution, but quality can often be traded off for speed. In draft mode, a printer might print 10 or more pages per minute with quality comparable to dot matrix. In high-quality mode, inkjet printers can produce full-color photos that rival a conventional photo process, but a single such photo may take several minutes.
Inkjet printers form the starting point for 3D printing technologies.
3D Printing Concepts
Inkjet printers produce images by projecting ink onto a flat sheet of paper. Other media can be used, such as fabric or plastic, but the image remains a 2D image formed by ink.
3D printers use essentially the same method with a couple of important differences:
- The material used for printing is a powder or liquid that becomes solid after printing
- Multiple layers are printed on top of one another, each adding some height to the printed product
The surface on which the printing is done could be paper but more likely is a fixed solid surface. This is a work surface and the printed object will be removed from it when completed.
3D Printing is a special case of Additive Manufacturing (AM) — creating an object by gradually adding material rather than starting with a larger object and cutting away. This may take place on a large scale manufacturing floor, but 3D printers are self-contained and suitable for use by small businesses or even hobbyists. When compared to AM, conventional manufacturing processes are called Subtractive Manufacturing (SM).
Printing with Plastics
The process used by most 3D printers today is called Fused Deposition Modeling (FDM), or Fused Filament Fabrication (FFF). Both terms refer to essentially the same process, but the first term is the original name and is trademarked.
The material used for printing in FDM/FFF is usually a plastic material (several types are used) initially supplied as a long coiled filament. The plastic is fed into a nozzle, which heats it to the melting point and extrudes it onto the object being built. The plastic then solidifies when it cools.
This diagram illustrates the basic process. It also shows plastic rods of a different material (letter d) that may be needed for temporary supports while the object is being built. These supports are designed to be removed after the object is complete.
Although plastics are the simplest and most common materials for 3D printing, other materials are sometimes used, ranging from synthetic wood to chocolate to human tissue. Some of these applications are discussed below.
Printing with Metals
A family of alternative processes may be used to construct machine parts and other complex objects out of steel and other metals. These processes have a variety of names such as Electron Beam Fabrication (EBF), Direct Metal Laser Sintering (DMLS), or Selective Laser Melting (SLM). These processes are much more expensive than plastics-based methods and suitable mainly for specialized manufacturing. But they are capable of producing metal parts with strength and other properties that match or exceed parts manufactured by conventional techniques.
These processes differ in details but have some things in common. They start with powdered metal, typically steel or titanium. A laser or an electron beam is used to melt or partially melt (sinter) small amounts of this powder which are then deposited through a nozzle. In some cases, this process must take place in a vacuum chamber.
3D Printing Software
All computer printing is driven by data files that describe what is to be printed, and software that is used both to create these data files, and then to interpret them to do the actual printing.
In 2D printing, pages to be printed are usually originally designed and created directly by humans. Simple character codes generated from a keyboard represent text. Various font files may be used to construct the actual characters, and graphics may be incorporated using a variety of representations. The completed file is then often converted to a page description language such as Postscript or Portable Document Format (PDF) which is interpreted by the printer software to produce the printed page.
In 3D printing, objects are represented by a 3D modeling file, most often using the STereoLithigraphy (STL) file format. There are two main ways of producing these files:
- They can be generated by computer modeling of the object to be produced using various types of Computer Aided Design (CAD) software
- They can be produced by scanning an existing example of the object to be produced or modeled using a 3D scanner
Special software may also be used to construct STL or other modeling files from a suitable set of ordinary photos of an object. Many complex modeling files are available for downloading, either for purchase or in many cases for free.
Evolution of 3D Printing
The genesis of 3D printing lies in two principal predecessors: inkjet printing, as discussed above, and additive manufacturing.
Additive manufacturing was first developed in the 1980s. In 1984 two separate patents were filed for stereolithography, one by a French group and one by Chuck Hull of 3D Systems Corporation in the USA. The 3D Systems method was the first to be developed commercially. It involved curing photopolymers with lasers. This work also resulted in the development of the STL file format and related modeling techniques. 3D Systems continues to produce 3D printers today.
The FDM process discussed above was developed in 1988 by S. Scott Crump and commercialized by the Stratasys Corporation. The first commercial FDM printer was produced by Stratasys in 1992. Stratasys went on to grow and acquire several companies with related technologies and remains also one of the principal suppliers of 3D printing technologies.
The term “3D Printing” was first used for a slightly different process developed at MIT in 1993 and commercialized by the Z Corporation. This process alternated depositing layers of powdered material and layers of a liquid binder to form the actual shape. Z Corporation was later acquired by 3D Systems.
Another important company in 3D printing, Solidscape, first appeared in 1993. Solidscape specializes in producing extremely high precision wax models. These models are used to produce fine jewelry and precision industrial objects.
At their outset, 3D printers were sold or leased for tens of thousands of dollars. Today it is possible for hobbyists to purchase a low-end printer for under $1000. Kits are also available enabling potential users to build their own. Information abounds for those interested in exploring the technology.
The metal-based techniques discussed above evolved a little later out of conventional manufacturing activities. Originally, automated numerical control tools were focused exclusively on processes that removed metal (subtractive methods). By the early 2000s, additive manufacturing techniques were being used selectively, and combinations of additive and subtractive techniques were becoming common.
How is it being used?
Originally the primary use envisioned for 3D printing was to produce models and prototypes in preparation for building the final object using conventional techniques. As 3D printing has matured, and its potential is being recognized, a huge variety of uses are emerging. Here we can highlight only a few.
As already discussed, 3D printing is extensively used to construct preliminary models and prototypes of objects to be built or manufactured in the future. These objects can range from engine parts to architectural designs.
Metal based techniques are capable of producing parts with all the strength and quality of those produced by conventional techniques. These are being used especially for specialty and replacement parts for machinery, vehicles, appliances, and other areas.
A fascinating and unexpected use that is rapidly becoming popular for 3D printing is food production. Here uses can range from decorative desserts such as sculptured chocolate creations, to production of ready-to-bake pastry items such as cookies or pizza.
A great variety of medical applications exist for this technology. One area is custom medical devices, from dental implants to prosthetic limbs. In some cases these items, which are fitted to the patient and usually need to be sent to special labs for production, can now be manufactured quickly in medical and dental offices.
3D printing has been used to produce implantable objects such as bone replacements, and to model parts of a patient’s body for study in preparation for surgery. One of the newest and most exciting applications, known as bioprinting, is the use of human cell and tissue preparations to produce specific cell structures and, in some cases, artificial organs. Today these are being used mainly for research, but the time is near when these tissues and organs may find increasing use as actual body replacements.
3D printing also has a huge range of applications in art. Any type of sculpture that can be designed (and is not too large) can potentially be realized in a range of suitable materials (including synthetic wood). Totally accurate portraits are easily produced by scanning the subject with a 3D scanner.
One controversial application that must be mentioned is the printing of firearms. Early 3D printers were capable only of producing models and prototypes. Some of today’s printers can easily produce fully functioning guns of many types including automatic. In the past steps were sometimes taken to deny access to 3D printers for users who planned to produce weapons, or to suppress the distribution of design files. In the long run, though, these steps cannot work and we must accept the fact that some firearms will be produced in this fashion.
So where is 3D printing technology going? It seems clear from the above discussions that 3D printing is here to stay, and its applications will continue to grow. In many fields including general manufacturing, medical, art, and others it is seen as a revolutionary technique. Undoubtedly you have some objects in your house today produced by 3D printing methods.they may also play a role in your medical future. These processes will continue to expand their possibilities and influence (hopefully in a good way) many of our daily life experiences as time goes by.