Autofab is a family of modern technologies for generating 3-dimensional, solid objects under computer control. Starting shortly after World War II with the invention of automated mills and lathes, the industry grew to $8 billion in annual worldwide sales by the early 1990s. The recent introduction of additive processes, which literally build up the desired objects one particle at a time, has been heralded by some to be ushering in a new era of manufacturing, a Second Industrial Revolution.
In July 1994, the Research and Technology offices of AlliedSignal, Inc. produced an internal Technology Exchange Conference on Rapid Prototyping of Functional Components. This article is based on the keynote address by Marshall Burns at that meeting. Dr. Burns was asked to speak about where research on automated fabrication is likely to take the field in the future.
To understand the future, it helps to take advantage of what we know about the past. So let me start by going back about 3,000 years to a beautiful river valley in Iraq, then known as Babylon. Some people believe this place was the site of the Garden of Eden. Babylon was a little collection of farm towns and industrial villages, and it was the envy of the Western World. It had a vigorous market economy, a codified legal system, and an efficient government. The Babylonians were dynamic entrepreneurs, but they were severely limited in their transactions, for one very important reason. Lets say you were a farmer, and you wanted to sell 40 bushels of corn to your neighbor. You negotiate a price, and he agrees to pay you the 40 tetradrachma when his goats go to slaughter. But according to law, your agreement is unenforceable unless it is written down and signed by both parties. So what is the problem? Neither you nor your neighbor knows how to write!
As in every market economy, the solution to your problem is readily available. You and your neighbor walk down to the gates of the village, where you hire the services of a scribe. The scribe listens to the details of the transaction, and then writes them on a small clay tablet. You and your neighbor apply your personal seals to the document, you pay the man his fee, and you go off to transact delivery of the corn.
Until a few hundred years ago, the scribe was a highly valued specialist in the modern technology of written language. Clay tablets with cuneiform markings were one of the first techniques developed for the permanent storage and transmission of artificial information, but they required a very special skill to operate. For more than 2,000 years, the scribe was an elite practitioner of this technology and a series of improvements on it, like the one that replaced clay tablets with scrolls of papyrus.
The businessman was beholden to the scribe until a marvelous invention hit the market in the 15th century. I am not referring to the printing press. The printing press was a necessary force behind the development of literacy, but remember that Gutenberg could publish all the scrolls in the Library of Alexandria, and if no one could read them, the impact would be minimal. The technology that finally liberated the medieval businessman from the tyranny of the scribe was the technology that created such demand for the skill of reading that suddenly everyone felt an urgent need to do it. It was the book, a stack of paper sheets bound together along one edge. For the first time, the book made it convenient to store and retrieve information in a permanent form.
Now imagine that. For 25 centuries, business people of great wealth and intelligence remained locked in to the services of a craftsman whose primary skill was what? That he could read and write! A skill so elementary that we worry about a child today who has not mastered it by the fourth grade! Why in the world would billions of people remain illiterate throughout history? And if reading is hard to learn as an adult, why, at least, didnt everyone make sure that their children learned to read? Why? Because there was nothing to read! Aside from the occasional contract in your business, and a bunch of musty scrolls in a dingy basement at the local monastery, there was no reason to go to all the trouble of learning to read.
The invention of the book changed that. Suddenly, there were books on agriculture and law, books on literature and fashion, books about war and books about love. The availability of the new portable information medium caused an explosion of software development that resulted in the publication of thousands of titles of interest to entrepreneurs and aristocrats, without the nuisance of finding a scribe to read it to you.
The availability of books caused an explosion in literacy that broadened the minds of individual men and woman. It opened for them a window to new worlds. It let them experience the adventure of explorers without risking scurvy. It brought them the ponderings of the great philosophers without traveling to distant lands to hear them lecture. And it let them experience the beauty of a Shakespearean play without ever setting foot in a theater.
Books are an example of what I call an emancipating technology. An emancipating technology creates freedom in the world for the great majority of people to work and play independently in a new way that was previously restricted to a few.
What is another example of an emancipating technology? The automobile may spring to mind, and it may seem to us today that this is what freed us from the need for railroads and wagon trains to travel across country. But remember, for many years the motor car was a piece of heavy machinery that was almost as difficult to operate as a locomotive. The ultimate symbol of this difficulty was the hand-crank that was needed to start the thing up. The real emancipation in land transportation came with a series of improvements in the automobile that made it accessible to ordinary people. The first and most important of these was the automatic starter that replaced the hand crank. The others were the synchro-mesh transmission, which removed the difficulty of downshifting into first gear, and then power steering and power brakes. It was these improvements in automotive technology that opened up the continents to individual transportation, and created new vistas of freedom for people to explore and exploit. These improvements and conveniences made it worth peoples while to learn the skill of driving, and hundreds of millions of people around the world have since taken it up.
Now, notice that technologies are not born, and do not live, in a vacuum. No important technology can proliferate unless it grows on top of, or in concert with, another set of technologies that form its infrastructure. (Table 1.) These supporting technologies provide the environment necessary for the convenient and productive use of the primary technology. For example, consider books again. The idea of binding pages between covers actually appeared before the printing press was invented. But the process of manually writing out the contents of each page was so expensive that there was little practical advantage to the book over the more common medium of the scroll. But the printing press allowed books to be manufactured with an efficiency that made their mass distribution become practical for the first time. So, a gradually increasing population of presses throughout Europe became the infrastructure that supported the publication of books. In a similar way, without the paving of roads and highways, the use of automobiles would not have been comfortable enough to attract a large market, whether the cars had auto-starters and power steering or not. With the combined growth of their respective infrastructures, books gave people the individual freedom to learn, and self-starting cars gave people the individual freedom to travel.
|TABLE 1. Three domains of human activity and the technologies which make them freely available to the great majority of people in industrial cultures. In each case, the success of the emancipating technology has required the proliferation of a supporting infrastructure.|
|Domain||Requisite Infrastructure||Emancipating Technology||Era|
|Education||Printing presses||Book||15th century|
|Land transportation||Pavement, gas stations||Self-starting automobile||20th century|
|Hard-goods manufacturing||3-D CAD software||Fabricator||21st century|
|Figure 1.14. A fabricator allows an engineer or designer to create models or machine parts directly from a computerized description and raw material. [Courtesy 3D Systems, Inc.]|
Lets now look at a more recent emancipating technology. This one is supported by the development of 3-dimensional CAD tools, and is starting to give people a new freedom to create tangible material objects. Automated fabrication is a family of modern technologies that generate three-dimensional, solid objects under computer control. (Figure 1.) They use raw materials and computer data to create real, solid objects you can hold in your hands, submit to testing, or assemble into working mechanisms. Autofab uses fabricators, which are like computer printers except, instead of printing flat images on a sheet of paper, they fabricate real objects. Real, solid objects with almost any 3-dimensional shape you want, including internal passages if desired.
Automated fabrication started more than 45 years ago with the invention of numerically controlled (NC) machining. These subtractive processes start with a solid block of material and carve it out to reveal the shape of the desired object. In the 1980s, several additive techniques were developed, which literally build up each object one particle at a time. These processes work with photocurable plastic resins, thermoplastic powders, adhesive droplets, or other specially devised materials. Together, subtractive and additive autofab now offer modern manufacturers the ability to prototype and produce new designs faster and cheaper than ever before.
Automated fabrication is an $8 billion industry in terms of worldwide fabricator sales, mostly subtractive. All major manufacturers, and many smaller ones, use autofab in their design or production facilities or both. In addition, this is one of todays hottest areas of research. Hundreds of laboratories around the world have projects dedicated to improving autofab processes, or inventing new ones. Future fabricators will go far beyond todays capabilities to offer higher-resolution, faster object generation, and other substantial improvements.
Autofab is useful and economical when only one, or a small number, of an item is needed, and when the item is not easily made by manual processes. Autofab can also help however in generating larger quantities, when it is used to make the molds or dies in which an item is replicated. Some people believe that the ability of fabricators to reduce the cost of low-volume production is bringing about a radical change in the very meaning of manufacturing. The era of mass production and mass customization may be giving way to a new era of customer coconstruction, where the manufacturer and customer work together for optimal, mutual satisfaction.
Some proponents call this technology rapid prototyping because industrial prototyping was the first major application of the new additive fabricators, like the StereoLithography Apparatus (SLA) from 3D Systems. Hundreds of millions of dollars in productivity gains have been realized by the few hundred companies around the world who have been using these and similar machines to make prototypes of new machine designs. But to call these machines prototypers misses the whole point of what is happening here. Calling an SLA a prototyper is like calling an automobile a grocery cart because one of its first important uses was in rounding up supplies for the family, or like calling a book a scripture because one of the most popular books ever published has been the Holy Bible.
SLAs and similar machines are not prototypers, although they may be used that way. These machines are fabricators, because they create new solid objects out of amorphous material and computer data.
Today, the field is still so new that we have to call these devices automated fabricators. This is so that we dont confuse them with human fabricators, the craftsmen who still work with great skill in fashioning objects by manual methods, usually out of sheet materials. Forty years ago, when IBM launched its model 650, it was called an electronic computer, because the term computer at the time referred to a human practitioner we would call today a key-punch operator. These human computers operated machines called tabulators, which were basically big, mechanical adding machines. So IBM at first had to distinguish its machines by calling them electronic computers. Today, the word electronic is no longer necessary, and everyone understands that you mean a machine when you speak of a computer.
In the same way, in ten or 15 years, we wont need to speak of automated fabrication anymore. When you speak of fabricating some design, or fabbing it, for short, people will understand that you are talking about using a machine to render in solid material a design that yesterday existed only as so many bytes on a computer disk. Automated fabrication will become just fabrication, and everyone will know what you mean.
Research and Development Today
|Figure 8.1. The triad of technical issues involved in the development of automated fabrication technologies.|
Lets look now at some of the research that is going on in industry, university, and government laboratories around the world to advance the state of these technologies. Research and development in automated fabrication can be broken down into three categories: process, materials, and control. (Figure 2.) These fields are not studied in isolation, but each one is intimately linked to the other two. Lets consider some of the challenges in each of these areas.
Autofab processes come in three varieties, which can be called subtractive, additive, and formative. (Figure 3.) This means that you can make a 3-D object by either removing material from a solid block, by fusing individual particles, or by pressing on opposite sides of a piece to change its shape without either adding or removing material. There are no commercial fabricators on the market today that work by strictly formative methods, but some projects underway are likely to lead to some interesting developments in coming years.
|Figure 1. The three fundamental fabrication processes, which form the bases of, from left to right, subtractive, additive, and formative fabrication. It is the automation of these processes that gives rise to autofab.|
Fabricators do not necessarily use only one type of process. For example, the Helisys LOM, which bonds successive sheets of material and cuts out a pattern in each one, uses a combination of additive and subtractive processes. Similarly, there are hybrid machines that combine subtractive and formative processes. These are combination CNC punch press/press brakes; they take raw sheet metal in one end and turn out anything from desk drawers to refrigerator panels by cutting holes and bending the material into shape.
Some people think that subtractive autofab, or CNC machining, are yesterdays news, and that we can forget about them as the additive ones improve with time. I dont agree. Automated machining has benefited and advanced tremendously from the same computer revolution that has made the additive processes possible. Modern lathes, for example, can cut noncylindrical shapes out of round stock, using so-called live tools and coordinated motion of the spindle and turret.
While there is value in improving on older techniques, the ultimate style of autofab lies in a totally new direction. You simply cant do any better than manipulating material in terms of its individual atoms. The first example of this was done when Don Eigler and his colleagues at IBM wrote out the logo of their company by sliding xenon atoms around on a nickel surface with the tip of a scanning tunneling microscope. This work foreshadowed some very exciting work that will eventually merge the fields of automated fabrication and molecular engineering to yield total control over the chemical structures of fabricated objects.
Moving to the second area of autofab R&D, materials research, we ask how to involve new types of materials in existing processes, and how to improve the material properties obtained from a fabricator. Some of the most exciting work in this area involves attempts to perform additive fabrication directly in metals. One example uses a 3-dimensional welding technique at the University of Nottingham in England, which is an idea that has actually been around for some time. Another important type of material, in which AlliedSignal and other important organizations are investigating new techniques for fabricating, is ceramics. Ennex Fabrication also has a development effort underway that is exploring a novel technique for working with metals, ceramics, and advanced composites.
Aside from the type of material being used, materials research also looks at how to form the material in the most optimal fashion. Automated fabrication has created a new opportunity for engineers to control what might be called the millistructure of an object. This little-explored technique will allow engineers to vary the properties of objects as easily as artists today change the colors of a 2-D design in a computerized paint program.
|Figure 8.9. Process map of automated fabrication, with the control issues in the shaded area. The key elements, shown here with underlined labels, are the representation of abstract geometry in computer code and the translation of this code into machine instructions to direct the fabrication process.|
That leads us to the third category of autofab R&D. Control is the essence of automated fabrication. It is the link between the mind of the user and the physical processes at work in the machine. Figure 4 shows a map of the general autofab process, with the control aspects highlighted in the shaded area. The root of everything is in the abstract, 3-dimensional geometry that describes the shape of the object to be formed. The first key element of control is the representation of this geometry in computer code. Next that code must be translated into machine instructions that guide the fabrication process in the fabricator. The other arrows in the diagram show the closure of various feedback loops that help to improve the outcome of the process. The sequence from geometry to computer code to fab process to solid object is the road of emancipation that will bring each of us the freedom to create tangible solid objects at will.
Impact of Autofab on Tomorrows Factory
What results can we expect to come about from this research on autofab processes, materials, and control? In time, we can expect to see processes that work at smaller and smaller scales, and that operate much more quickly than todays machines. New fabbers will be developed that work in the entire variety of known materials, including living tissue. We will see big, room-sized machines and small, table-top units. Computers will come with 3-D displays and digital and voice controls that invite you to sculpt your desired geometry in mid-air with your fingers. And a new type of accessory will arise, a robotic assembler. If what you want to make is a machine with separate parts, the assembler will reach into the fabricator, remove each part as it is finished, and put them together to create your machine for you.
Now, what will these amazing advances mean to the factory of tomorrow?
The automated fabricator can be seen as the 3-dimensional analog of a laser printer, and that is how we can understand how to use them. How do you use the laser printer in your office? If you write a letter or a memo to be sent to just one person, maybe with a copy to someone else and a copy for the file, you will run the whole thing off on your laser printer. The original will go on company letterhead; maybe the file copy will go on less expensive bond paper. Now, if you write a memo to be distributed throughout the office, maybe 25 or 50 copies, then you will run off just one original on your laser printer, and you will use this as a master to make whatever number of photocopies you want.
Fabricators will be used in just this way. A fabricator is always a low-volume device. You will use it to run off just one, or a very few, of the object you want. If you want a few dozen, then youll use the fabricator output as a master in one of several replication processes, like silicone rubber molding or injection molding. The master you make in the fabricator may be a direct negative, which means that it is a mold into which you pour the copy material, or it may be a positive, in which case you make a negative copy to get your mold.
The ability to run off individual models overnight has already had a dramatic impact on the productivity of organizations that are using autofab. Let me list some of the impacts that are being seen today, and that will come about later as these technologies develop and mature:
- Better quality. When you have the luxury of running off designs overnight or faster, you can run more iterations of your idea. You can take more care to work out the bugs, and get it right.
- Shorter life cycles. Even though improved quality will make your products able to last longer, the ability to iterate your designs goes on continuously. Continuous product improvement and development will bring your customers back for the latest versions of your products.
- Recyclability. The combination of improved quality and shorter life cycles creates a conflict in the mind of the customer. He or she doesnt want to throw away a perfectly good product thats only a few months old, but they do want to get that latest version that youve just developed. The answer to this dilemma is to consume the old product in manufacturing the new one. This has been going on for years in the automotive parts industry, where, for example, you get a discount on brake shoes if you bring in your old ones for remanufacturing.
When you walk into a store today, whether its a hardware store or an automobile showroom, your focus is on the items shown for sale on the shelf or on the sales floor. You may be able to order a certain model with a different color upholstery, but basically, what you see is what you can get. In the future, a customers buying focus wont be so much on the physical product, as on the process used to create it. There will be no limitations to existing products; the customer will be able to specify differences, not only in appearance, but also in structure and functionality. The modern era of mass manufacturing will fade away as manufacturers learn to deal with customers on an individual basis, and create each product from scratch for each customer.
The 21st-Century Factory
Prior to the first industrial revolution of the 18th century, manufacturing was carried out by independent craftsmen in each town and village. Now autofab, and what some people are calling the second industrial revolution, may return manufacturing to its decentralized roots. Lets look at some statistics in a related field to see how this might come about. (Table 2.)
|TABLE 2. Recent growth in the number of book publishing companies in the U.S., due to availability of inexpensive computers and laser printers, with analogous growth possible in manufacturing due to availability of inexpensive fabricators.|
|U.S. Book Publishers||U.S. Hard-Goods Manufacturers|
|1970: 3,000||1992: 440,000|
|1990: 27,000||2012: 3,960,000|
|Sources: Publishers Distribution Service (publishers),|
Dun & Bradstreet Information Services (1992 manufacturers).
In 1970, there were 3,000 publishers of books in the United States. Twenty years later, this number had multiplied by almost a factor of ten. Why? What changed between 1970 and 1990 that caused the number of publishers to mushroom like that? The answer is that desktop publishing, which basically means the combination of cheap computers and cheap laser printers, made it possible for anyone with a little cash and a good idea to become a publisher. Before personal computers, typesetting and laying out a book was a tedious, expensive process, almost as hard as actually writing the words of the book itself. But this is no longer true. With a good word processing program and a laser printer, it is now fairly easy to produce a professional layout for a book or any other kind of publication.
What might happen if we apply the same logic to manufacturing? Today, there are close to a half-million companies in the United States whose primary business is manufacturing hard goods. This means furniture, automobiles, computers, car parts, airplanes: basically anything except food, clothing, and printed matter. What might happen in the world if the manufacturing analog of desktop publishing should come about? This is what some people have called desktop manufacturing. If we take the experience of the book publishing industry as a guide, we might expect the number of manufacturers to grow so that in 20 years there would be close to 4 million of them.
Now look at that number. With a total population of about 250 million people, 4 million means there would be a hard-goods manufacturer for every 60th man, woman, and child in the country. There is no way to reach these kinds of numbers without seeing little Mom-and-Pop operations sprouting up in every neighborhood of every town and village. And this makes perfect sense. As basic fabricators become less expensive, and 3-D CAD software becomes easier to use, we will see a growing movement of garage tinkerers who will buy them and use them to make little customized products for their neighbors, or for sale by mail order or over the Internet. These will be the pioneering entrepreneurs who exploit the new freedom to create given them by automated fabrication.
In fact, this movement has already started. In the world today, there are several hundred small businesses that offer contract services on additive fabricators. By combining this with some auxiliary equipment, these companies provide prototyping and prototype tooling services to manufacturing customers in their local areas and sometimes over much broader regions. In my view, these entrepreneurial businesses are the beginnings of the ground swell of small, community-based, agile manufacturing facilities of the 21st century.
How far could such a boom in manufacturing take us? As I share my thoughts on this, please understand that I do not claim expertise as a futurist. I am just a physicist who is obsessed with automated fabrication. But Ive been asked to anticipate the future, so I have tried out my best crystal ball attitude to see what seems likely to happen in the next 50 years. It was only in 1969 that the first human being set foot on the Moon, and I believe that long before 50 years from now, we will have returned to the Moon, and we will have established a growing settlement there. Furthermore, I believe that automated fabrication will play a major role in bringing that settlement about. In fact, automated fabrication is probably the most radical factor that will make space habitation feasible for the first time, and forever.
Why is autofab so important to space habitation? It is for the same reason that the Apollo program did not germinate a Lunar settlement: money. It was just too expensive to continue or move beyond Apollo in the face of other priorities that arose. The reason it was too expensive was that to build a settlement on the Moon, we had to first build it on Earth, take it apart, ship it to the Moon and put it back together again. It was the cost of shipping that killed the whole program. It was just too expensive to take all our stuff: our homes, our tools, and everything else we would need up there.
In that light, it is a very interesting fact that the surface of the Moon is thick with metallic and ceramic powders. There is plenty of iron, aluminum, magnesium, and silicon. These minerals are not lying around in their pure forms, but they are accessible to various physio-chemical processes. So, while we could not have done this in the 1970s, by early in the next decade, you will be able to send a few folks up there with nothing but a six-months supply of groceries and a couple of fabricators (plus some hydrogen to make water; there is plenty of oxygen in the rocks.) This crew will be able to build their homes, their tools, a Lunar factory, and a Lunar observatory, using only a few fabricators and the piles of Moon dust lying around their landing site.
This is the factory of the future. It is not only a factory that uses fabricators, but it is a factory that is built by fabricators. And it is the factory that will spawn a new era of economic development that has not been seen since the rise of the New World in America. There will be many factors that will bring this future about, and automated fabrication will be important among them.
Everyone reading this article was born into a world in which the individual freedom to learn and the individual freedom to travel had been well established by the technologies of books and self-starting automobiles. We are very lucky to find ourselves with the privilege of participating in the birth of a new freedom for humankind, the individual freedom to create tangible solid objects at will, brought about by automated fabrication.
| A fabber (short for digital fabricator) is a factory in a box that makes things automatically from digital data. Fabbers.com is under development to bring you the latest information on fabber technologies, applications, and markets.|