Rapid prototyping: rapid, colorful, real, and coming to a desk near you.

When stereolithography and rapid prototyping (RP) were introduced at Autofact in 1986, a seat for 30 CAD software and a high-end workstation was $40,000 to $50,000. Now, 30 CAD software, the source for RP data, goes for $500 to $5,000 a seat. And so there's now 3D printing for office applications in addition to machines for the factory floor.

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THE COPIER ROOM--REVISED

The current "final frontier" for rapid prototyping (RP) is the everyday, clean, relatively quiet office. So-called "3D printing," versus rapid prototyping, says John Kawola, vice president of sales and marketing for Z Corp. (Burlington, MA; www.zcorp.com), has gained market share over the last two or three years. "The whole idea with a 3D printer is, 'Hey, I can make this [prototype] in two hours and it costs ten bucks, so let's bring it to the meeting.'" In fact, with Z Corp. monochrome 3D printing systems going for $25,000 and full-color systems for $50,000, Kawola asks: Why would anyone not make a part every day during the design process? Other barriers to 3D printing have also dropped. Take speed, for instance. Z Corp.'s latest high-definition color 3D printing system, the Spectrum Z510, prints two layers per minute--figure 2" per hour. (Layers are user selectable from 0.0035 to 0.008 in.) Next, the Z510 doesn't need a dedicated person to run the machine. Plus, it runs off the 110 VAC from a wall outlet and it fits in the corner of an office or copier room. The Spectrum Z510 system can produce parts within a 10 X 14 X 8-in. work envelope. The model resolution is 600 dpi by 540 dpi. The machine itself measures 42 X 31 X 50 in. and weighs 450 lb.

The price of materials--the powder, binder, and ink that's used to print onto the powder--is also no longer a barrier. "Then there's the amortization of the print head. We use off-the-shelf Hewlett-Packard print heads," explains Kawola. All together, finished parts cost about $2.00/in.[.sup.3]. That's a solid cubic inch. Parts are typically hollow or honeycombed inside, so less powder is used and the price per part drops. (Powder not used to make a part, i.e., not made solid, can be reused.) The printer works just like a conventional home or office color printer. It prints in cyan, magenta, yellow, and clear or white. Those four colors combine to theoretically create 16 million colors. In addition to coloring prototypes to match their end use, people use color for labeling, adding arrows and circles to highlight features, printing engineering text or revision blocks, and tagging prototypes with date information.

Another office entry is the Eden260 from Stratasys (Eden Prairie, MN; www.stratasys.com), a photopolymer-jetting system manufactured by Israel-based Object Geometries. This RP system, explains Fred Fisher, product manager for Stratasys' Eden Distribution Line, is a "glorified hot-glue gun": Solid material is heated up, extruded in a semi-viscous state, and when it cools, it hardens into a solid part. The system builds layers by jetting out tiny droplets of resin on top of the previous layers of resin, like an inkjet printer jets out tiny droplets of ink onto a piece of paper. Resolution is 16 microns (0.0006 in.). PolyJet modeling materials are fully cured with UV light during the modeling process. Post-processing consists of removing the supports used to make the model, which is done at a standard water-jet station. Costing $99,000, the Eden260 can produce parts up to 10.2 X 9.8 X 8.1 in. The unit itself measures 34 X 30 X 47 in., weighs 620 lb., and plugs into any wall outlet.

3D Systems Corporation (Valencia, CA; www.3dsystems.com) also has an office unit. Made by Israel-based Solidimension Ltd., the InVision LD 3-D Printer builds parts one slice at a time using 3D Systems' VisiJet LD100 engineered plastic. This material comes off a roll like fax paper in an old fax machine. The result is a dry part (with supports that break off as desired). The LD 3-D printer is targeted for communication and concept modeling applications, yet its low price--$22,900--makes it also ideal for industrial design departments. These 3D printers, points out Elizabeth Goode, 3D Systems' director of corporate development, "provide complementary solutions for a growing number of 3D CAD users who want to create multiple design iterations cost effectively within the convenience of their offices."

BACK ON THE SHOP FLOOR

At the other end of the scale in terms of size, 3D Systems introduced a new line of automated selective laser sintering (SLS) manufacturing systems: the Sinterstation Pro 230, which can accommodate build volumes up to 22 X 22 X 30 in., and the Sinterstation Pro 140, which can accommodate build volumes up to 22 X 22 X 18 in. Both systems are for high-capacity, heavy-duty, automated rapid manufacturing. Says Goode, "We want customers to be able to put these machines out on the shop floor next to their CNC machines as an alternative manufacturing platform to traditional injection molding, casting, and machining methods--without the need to invest in expensive tooling, time consuming set-ups, and labor-intensive secondary operations."

Sinterstation Pro features a reusable material cartridge, a removable part-build chamber, a finished-part retrieval station, and an automated materials recycling module. The part bed, where the part is built, can be exchanged with a new bed to start the next build, thereby minimizing downtime. Unused powder is recycled by mixing it with new material, thereby saving material costs. And the material recycling unit connects directly to the Sinterstation Pro, thereby reducing the time and hassle in filling the machine with new powder. New closed-loop thermal controls help ensure consistent parts manufacturing from build-to-build and system-to-system.

WHAT'S RP WITHOUT RP MATERIALS?

3D Systems has a new photopolymer-based plastic for its InVision SR 3-D printer: VisiJet SR 200 Plastic. This material is about two to three times stiffer and stronger than 3D Systems' other VisiJet material, M100. Parts made of SR 200 better mimic the general performance characteristics of high-volume thermoplastics, such as polypropylene and ABS. While VisiJet M100 comes in five colors (black, blue, gray, red, and natural), SR 200 comes in only one color: "natural" (translucent white).

3D Systems' DuraForm AF plastic ("AF" stands for "aluminum-filled.") is a powdered aluminum-like engineered composite for all 3D Systems' SLS systems. The cured plastic looks like cast aluminum, yet it has the surface finish and fine-feature definition of nylon, and the stiffness of an engineered composite. It is targeted for applications such as automotive models, jigs and fixtures, casting patterns and functional prototypes, such as cases and metal enclosures. Excess DuraForm AF removed during the SLS process can be recycled.

Then there's DuraForm Flex plastic, a tear-resistant, flexible plastic for 3D Systems' SLS machines that's used to produce rubber-like functional prototypes and end-use parts. These parts can substitute urethane, silicone, and rubber parts. DuraForm Flex can handle harsh environmental conditions, such as heat and chemicals (it doesn't dissolve in hydrocarbons, ketones, ethers, or alcohols). The material comes in red, yellow, blue, white, and black.

PC-ABS from Stratasys is a blend of polycarbonate and ABS plastic for the company's fused deposition modeling (FDM) systems. Although PC-ABS blends are widely used to manufacture many of today's plastic products, including automotive parts, it has not been available for RP. Company officials say the blend has excellent thermal properties, it is significantly stronger than ABS, and its feature detail is similar to that of Stratasys ABS modeling material. PC-ABS support material washes away with water, and it is available for the Stratasys FDM Titan, FDM Vantage S, and FDM Vantage SE systems.

Stratasys also offers VeroBlue, an acrylic photopolymer modeling resin manufactured by Objet Geometries for the Eden333 PolyJet system. It is said to be about 10% to 15% better than the company's traditional SLA resins, with improvements in tensile, flexural, compression, elasticity modulus, and notched Izod impact strength.

Stratasys also now has a material with rubber-like properties. Called Tango, this material is for Stratasys' PolyJet line. Two Tango materials are available: TangoBlack has a durometer (softness) of 61-A (Shore Hardness scale) and TangoGray has a durometer of 75-A. As with all of Stratasys' PolyJet line, these RP materials are in sealed cartridges that can be swapped in and out with ease and negligible waste. These rubber-like materials--Stratasys' Tango and 3D Systems' DuraForm Flex--are ideal for a variety of rubber-type automotive applications, such as gaskets, seals, exterior door trim, bumper trim, interior door detail, electric mirror adjusters, and such under-the-hood applications as hoses, belts, and other watertight parts.

By Lawrence S. Gould, Contributing Editor