3D Printers

Material Worlds

15 Nov, 2011 By: Cyrena Respini-Irwin

3D printing is finding myriad applications — from rapid and custom manufacturing to DIY projects to parts production in space — as reliability, affordability, and functionality reach new heights.


Throughout history, every human creation, whether a wheel or a spear or a shoe, began as an idea. That’s as true today as it was for our cave-dwelling ancestors. Over time, however, technology has eroded the period of labor that separates the light-bulb moment from the finished product. Today, thanks to 3D printing, we can give a design tangible form simply by pressing a button — no elbow grease necessary. Even to a technologically savvy denizen of the twenty-first century, it can seem very much like magic.

A little familiarity, however, is all it takes to transform the magical into the mundane. Although it’s been around for decades, it’s only been in the past couple of years that 3D printing has garnered widespread recognition among professional CAD users, enthusiasts, and the general public.

This burgeoning popularity isn’t just a result of more mainstream media coverage; falling prices, improved reliability, and a diverse menu of modeling materials, production methods, and delivery options have all contributed. Three-dimensional printing has grown into a practical, accessible, user-friendly technology offering benefits to AEC, manufacturing, GIS, and even consumer markets. Ofer Shochet, executive vice-president of products for Objet, summed it up this way: “[Users are realizing that] 3D printing is not just a great idea — it is already affordable for you, it can be a reliable part of your process, it can help you in your daily product design activities.”

Terminology and Techniques

Jargon can be puzzling in any industry — as CAD users well know — but the numerous names in play can make 3D printing especially confusing. Rapid prototyping covers the automated, additive construction of 3D models for all purposes, but the term itself neglects the growing application of the technology to create final-use items. Additive manufacturing is widely used but seems to have the opposite problem, at least to the layperson’s ear. Adding to the muddle are variants such as direct digital manufacturing and instant manufacturing, plus vendor-coined terms such as EOS’s e-manufacturing.

Standards organization ASTM International uses this definition:

3D printing, n.: Fabrication of objects through the deposition of a material using a print head, nozzle, or another printer technology. DISCUSSION: Term often used synonymously with additive manufacturing; in particular associated with machines that are low-end in price and/or overall capability.

Industry expert Terry Wohlers, principal consultant and president of Wohlers Associates and chair of the ASTM F42 Terminology Subcommittee, elaborated: “While additive manufacturing is the official ASTM industry-standard term for the technology and the industry, 3D printing has become the de facto standard. Among those using 3D printing as the generic, umbrella term are the mainstream media, bloggers and tweeters, the investment community, and major CAD companies, such as Autodesk and SolidWorks.”

Although the details vary, all the technologies under the 3D printing umbrella use similar processes to fabricate objects. In each case, 3D data — typically a model from a CAD program — is divided by the printer software into thin cross sections. (Most units support the STL file format, which most recent CAD programs offer as an export option.) Then the printer builds the tangible object by creating those cross sections as layers of material, one at a time. (Read the sidebar, “2BOT Carves Out Niche in Modeling Market.”)

The process is similar to reconstructing a whole tomato by stacking its slices atop each other. The CAD data determines whether the end result is a tomato or a ham; the type of printer, its resolution, and the raw material used determine whether the tomato comes out red and rough-textured, or gray and smooth, or marked with striations where each layer was added.

The most widely used technologies include:

  • Fused deposition modeling (FDM) and fused filament fabrication (FFF). A heated nozzle extrudes softened or melted material, typically a thermoplastic such as ABS. Inkjet-based methods.
  • Modeling materials are jetted through one or more nozzles. A layer of resin may be laid down and cured with UV light, or a binder may be jetted onto a bed of fine granules of photopolymer.
  • Selective laser sintering (SLS) and direct metal laser sintering (DMLS). A laser fuses granules of metal, polymer, or other material to form each layer.
  • Stereolithography (SLA). A UV laser creates layers by solidifying the surface of a liquid photopolymer reservoir.

Regardless of the method, users need a technology to consistently deliver expected results before they can make it an integral part of their workflows. “The issue of robustness is critical, especially for professional users,” said Shochet. “Today, customers almost take it for granted that the reliability is there.”

Joe Titlow, vice-president of product management for Z Corporation, agrees that the technology has matured to a point where it’s proven and reliable, and customers don’t have to worry about downtime. “If you go back even ten years, that wasn’t the case,” he noted, “but we’ve had that [reliability] for five to six years now.” According to Titlow, that reliability — and improved performance in areas such as model detail, smoothness, color, and accuracy — is what has enabled 3D printing to become standard operating procedure in many companies. “It’s the coalescing of these individual features that has made it mission-critical in a lot of cases.”

For Fred Fischer, director of business development at Stratasys, improved performance means “making the printed output look, feel, and act more like a part that came out of traditional CNC [computer numerical control] or injection-molding methods — and we’ll continue to see more of that realized.” User-friendliness has also improved notably, Fischer added. “If you rewind the clock, there used to be more of an art to operating [these machines]. ... 3D printers are continuing to become much more easy to use, just like 2D printers.”


When designing the Mount’n Mover, which holds computers and other items for wheelchair users, BlueSky Designs used a Stratasys Dimension SST 3D printer to print eight ABS prototypes (top) for $3,000 — $20,000 less than three outsourced metal prototypes. “The more prototypes we can get out there and get into users’ hands, the more informed we can be about the product’s strengths and weaknesses,” said mechanical design engineer Nick Lee. Images courtesy of Stratasys and BlueSky Designs.

 

Marketplace Modifications

Manufacturers are still the most prominent user of 3D printing, applying the technology to concept modeling, functional prototyping, casting, mold making — and increasingly, the production of end-use parts and products. Shochet noted that the medical and dental manufacturing markets have grown quickly in recent years; this is due in part to increasingly affordable laser scanning equipment that can quickly convert the unique contours of a patient’s ear canals or molars into CAD data.

“Architecture is a little behind the product development folks in the adoption of 3D CAD tools, and consequently 3D printing is trailing by a few years [in that market],” said Titlow. He noted, however, that “architects love models — they’ve been making models since before there was CAD.” In fact, Titlow said, a few AEC firms make the leap to adopt 3D CAD software because they desire the resulting physical modeling capability: “They’re so excited about 3D printing, it’s pushing them to get on board.”

Rise of the maker movement. The most dramatic change in user demographics in the past couple of years is the rapidly growing group of nonprofessionals — hobbyists, enthusiasts, and makers — motivated by artistic creativity, entrepreneurial spirit, or simple fascination with the technology. This groundswell is supported by a new category of “personal” machines that have a relatively small pricetag (less than $5,000) and a footprint to match. This newest group of machines joins the two categories marketed to professional users: commercial printers (approximately $5,000– $50,000) and 3D production systems, which offer the largest build sizes, best finish and feature detail, greatest number of material options, and most robust output ($50,000–$100,000 and more).

In early 2009, when Cadalyst published the 3D printing report “Almost Real,” 3D Systems was preparing to market its V-Flash personal printer for less than $10,000. Today, in addition to that unit, the company offers the Bits from Bytes BFB-3000 Plus — “the first preassembled 3D printer on the market from less than £2,000 [approximately $3,300]” — and the user-assembled RapMan 3.1, beginning at £795 (approximately $1,300).

Although the prices of these entry-level machines make them accessible to nonprofessional users, their capabilities cannot compare with those of more expensive models. Fischer cautioned that “today’s output quality really doesn’t lend itself to be used for anything other than a crude concept model.”

Making the most of office space. Prices are continuing to come down for office-oriented machines too; the professional entry point for FDM and inkjet-type technologies has dropped into the teens. When “Almost Real” was published, Objet had just released its Alaris30 desktop model at a price near $40,000. Less than two years later, the Objet24 entered the market, offering a similar build capacity for $19,900.

Users of desktop-sized professional machines share many of the same comfort and safety needs as home users, since they too will be in close proximity to the unit while it operates. For example, a modeling process that generates a large amount of heat might be fine for a commercial fabrication shop, but unacceptable in an office setting.

Shochet explained further: “’Officeability’ has a lot of meanings: no offensive noise or odor, and it uses chemicals that are similar to those that usually exist in the office environment [ in terms of limited toxicity]. There are some systems that produce more odor and need more ventilation, some that consume a lot of energy — such as sintering and melting plastic — but overall, the whole market is moving toward officeability.”

The Real Deal: End-Use Products

“The 3D printing industry was built on using the technology for making prototypes, and that’s arguably still the primary use, but it has really broadened into manufacturing end-use products,” said industry consultant Wohlers. “Fastforward 20 years, and this technology will have a much bigger impact. I truly believe it will develop to become more important and more useful than any other method of manufacturing on the planet,” he said. “Already, it is being used in so many ways and industries.”

As examples, Wohlers offered orthopedic hip-socket implants, airplane parts, and dental crowns and bridges. “The product volumes are relatively low, the parts are relatively small, and the value of each product is quite high — that’s when it makes the most sense to use additive manufacturing to make final products.” Wohlers believes that both hardware developers and service bureaus that have been focused on rapid prototyping — such as Stratasys, 3D Systems, EOS, Harvest Technologies, Solid Concepts, and Paramount Industries — are undergoing a transformation. “They will still build prototypes, of course, but the target is to move into part production with 3D printing. ... That’s where the money is, and that’s what’s exciting.”

This trend affects not only parts and products for business use, but consumer items as well. Service bureau Shapeways does a brisk business in 3D-printed earrings and candleholders, keychains and dice — all final products, ready for use. As of early this year, Wohlers reported, the company was creating about 12,000 products per month, with an average selling price of $14 per item. Although most are lasersintered out of thermoplastic powder, Shapeways adds new material options frequently, including glass, sterling silver, and ceramic.

Make it faster, make it better. Manufacturing with a 3D printer differs from traditional processes, such as injection molding or CNC machining, in several ways. Because there is no need for factory setup or tooling creation, production can begin as soon as the CAD data is ready. That can result in much shorter overall production times for small runs, even though each individual product takes longer to create than with traditional methods.

Custom products — ranging from hearing aids and prosthetic limbs to personalized giftware — are an excellent example of short-run manufacturing. “Prior to this technology, the manufacturing industry would produce custom products, but they were very expensive,” Wohlers observed. “Now it can be done affordably and relatively fast.”

Three-dimensional printing also enables improvements to the design itself; the layer-stacking additive build process can create overhangs, enclosed cavities, and joints that either cannot be achieved by traditional methods, or are prohibitively expensive. Consequently, the widget in question can be redesigned to be lighter, use less material, comprise fewer component pieces, and require almost no human intervention.

Aerospace companies such as Boeing, GE Aviation, and Northrup Grumman are exploring ways to use 3D printing to produce lighter metal parts with less waste. (When a part is milled from a solid piece of metal, as many aircraft components traditionally are, as much as 90% of that material becomes scrap, said Wohlers.) Airbus is redesigning the expensive metal brackets that anchor subassemblies such as galleys to the main body of the aircraft, reducing their weight by 50%–80% while preserving their strength.

Metal-based systems have gained traction in recent years, thanks to wider awareness of their capabilities; a greater number of material choices, including titanium alloys, cobalt chrome, and stainless steel; and certification by regulatory bodies. Wohlers noted that the U.S. Food and Drug Administration has cleared hip and spinal implants manufactured by electron beam melting (a process similar to SLS), and he predicts more approvals on the horizon.

 

Environmental issues. Unlike a digital prototype, which leaves behind no tangible debris, a 3D-printed model often ends up at the dump after it has served its purpose. The energy and chemicals required for various printing processes also raise concerns.

“Over time, we’re all going to have to look at environmental issues [associated with 3D printing],” said Cathy Lewis, vice-president of global marketing at 3D Systems. “For instance, today ... we offer PLA (polylactic acid) in a wide range of colors. PLA is a biodegradable thermoplastic that has been derived from renewable resources such as cornstarch and sugarcane. This makes PLA environmentally friendly and very safe to work with. The last thing we want to see is a future where we’re printing more junk, versus customized products built from biodegradable materials.”

Wohlers believes that users need to become better informed about the environmental impact of 3D printing — which includes the electricity consumed by the machine itself; the cost of shipping machines, materials, and parts to customers; and the energy used to produce raw materials — so they can make better decisions.

Plastic laser sintering, for example, requires a mix of 30% to 45% fresh material for each build. With metal sintering/melting, in contrast, almost all the material can be reused. Shochet pointed out that some polymers can be recycled to make the raw material for new prints, or ground up to create playground surfacing compounds.

On the other hand, manufacturing only the number of items needed promises waste-eliminating benefits for the environment and businesses alike. “With additive manufacturing technology, we can turn out a few of something, put it out there on the market, and if there’s sufficient demand, only then make more,” said Wohlers. “It can be the production method, or it can be used as a bridge to high-volume production.”

Matching Methods to Applications

Before selecting a method, companies must first determine that they have a legitimate need for 3D printing. It’s not appropriate for every application, such as large-volume production of end-use parts. Fischer likens the decision-making process to choosing a high-definition television: Buyers must first determine if — and how — the technology would benefit them, then decide which broad category of system would be most useful, and finally evaluate various products to find one that meets their needs.

“The technologies very much do matter, and they differ substantially,” Fischer continued. For example, FDM doesn’t offer the surface finish and level of detail required for jewelry designs, and it can’t print in full color, which is often desired for GIS applications and late-stage architectural designs. What it does provide is stable, durable, heat-resistant thermoplastic models that functionally test at 75%–80% of the strength of their injection-molded counterparts, Fischer said.

Laser-sintering machines, such as those from EOS and 3D Systems, also produce thermoplastic models that are strong enough for final products and rigorous testing. Sintering usually requires high temperatures, however, and the technology is more resistant to the ongoing slide in prices than are inkjettype methods, said Shochet.

Photopolymers, which are among the materials used by Objet and 3D Systems printers, are susceptible to warping as a result of exposure to heat, light, and humidity. “Photopolymers work well for concept modeling and prototyping a design,” said Wohlers, “but they don’t hold up over time.” He noted that such materials are also suitable for finished products that won’t be put under stress.

According to Wohlers, the costs of the various methods are “fairly comparable” at the professional level; one of the most important criteria is not price, but material properties. Does the user require a rubbery compound to test the tread on a new running shoe, or a clear plastic to observe fluid flow inside a medical device? Is the item composed of multiple materials, or is it homogeneous? Will the model undergo rigorous testing, or will it simply be passed around the room at client meetings?

To avoid disappointment, buyers should research options thoroughly and compare not only capabilities and purchase price, but the cost of ownership over time (including materials, maintenance, and electricity). Labor is also a factor: Does the machine produce support structures that will have to be cut or washed away from the printed item? Will the user need to apply a coating to strengthen or preserve the finished model? Is any sanding required to attain the desired surface finish?

Print it yourself, or order in? In addition to deciding on a method, companies must also consider a delivery model: purchase one or more machines for in-house use, send designs out for printing by a service bureau, or both? In addition to budget, the volume of items, frequency of projects, turnaround time, and security are all factors in this decision.

“When you reach a certain volume, it often makes sense to bring it in-house,” said Wohlers, but he noted that with some companies, demand frequently exceeds on-site resources, to the extent that it is actually faster to outsource. In-house printing also makes sense for sensitive designs that companies are anxious to keep under wraps. Will service bureaus be phased out as 3D printers of every type become more affordable? No, said Shochet and Fischer. They both believe 3D printing will evolve as 2D printing did, with users embracing its diverse options and using different delivery models for different applications.


David Munson created the “WTC Triptych” to show the World Trade Center site before and shortly after 9/11, as well as in its future rebuilt state (depicted here). The 17-inch-square models were 3D-printed on a Z Corporation ZPrinter and draw data from sources including 2D satellite imagery, Google Earth, photographs, publicly available 3D models, and Wikipedia. Image courtesy of Z Corporation.


Modeling the Future

The past couple of years have wrought big changes in the 3D printing industry; what can we expect in the near future? (Read the sidebar, “Zero-Gravity Tests Hint at a Galaxy of Applications.”)

Shochet has observed a consistent pattern: Technologies that are reserved for high-end machines today will be transferred to entry-level solutions tomorrow. “It’s usually three to five years from high-end to medium-range or entry pricing, but it depends on the technology. Ten years ago, if you wanted to use a clear material, you had to use a stereolithography machine that cost $300,000 to $500,000. Today, that same machine is down to $200,000, and you can print clear with an inkjet machine that costs less than $100,000 — and within a year will be less than $50,000.”

That doesn’t mean that the definition of “high-end” is static. Shochet compared the technology transfer to computing: “We had supercomputers ten years ago, that were similar in speed to what you have in your iPad now; at the same time, we have new supercomputers that are much stronger, much faster.” Likewise, printer capabilities — including material variety, versatility in colors, and material properties — are continually being expanded and enhanced. “The market is still not at the point where there is nothing left to add,” said Shochet.


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