Effective Low-Volume Approach
But additive manufacturing can be costly. Although this approach can't compete with the low per-unit cost of mass production, it's effective when it comes to manufacturing in low volumes, and often is quicker than traditional methods. "It's not always a cheap process compared to conventional machining," Kamleiter says. "But if you need a complicated part or a part that can't be machined in a short time, this is a cost-effective way to go."
Similarly, additive manufacturing enables the creation of a single part that has all the complex design features of what otherwise would have required three separate parts if manufactured through traditional methods.
Two of the most common additive manufacturing processes are laser sintering and fused-deposition modeling. The former uses a high-power laser to fuse powdered metals into fully dense 3-D objects, layer by layer. In the latter approach, a plastic filament or metal wire is unwound from a coil, supplying material to an extrusion nozzle. The model or part is produced by extruding small beads of material to form successive layers. In each case, the exact geometry of the part is defined by the 3-D CAD model.
At C&A Tool, once the rough part has been built through the laser-sintering process, workers complete the manufacturing process by performing the finishing work on its fleet of precision lathes and milling machines.
Another manufacturer that depends on additive manufacturing is GPI Prototyping, which uses laser-sintering systems built by Germany-based EOS, which also has offices in Michigan. "We have two EOS machines and we are building direct from 3-D CAD files," says Tim Ruffner, GPI vice president of new business development and marketing manager. GPI's medical customers use their products for trials for surgical instruments and surgical implants, "which can be done in days," Ruffner says. A typical production run of parts, he says, "is a couple hundred."
Driven by Design
One of GPI's customers is 3De, a rapid product development company in Fort Lauderdale, Fla. "We are producing an entire high-precision surgical system using this technology," says 3De founder Scott Hay. He is such a believer in the speed and flexibility of additive manufacturing that he calls it "a terrific win for American manufacturing." GPI produces the parts for 3De from CAD designs provided by 3De, and the latter finishes the raw parts -- polishing, anodizing, etc.
"You can capture any geometry you want," Hay says. "It's almost impossible to make the parts we are making with traditional manufacturing. High-precision milling is the only way you could produce these parts, and these are very complex tasks. There is only a limited amount of manufacturing skill out there that can meet these challenges." He adds that at least 30% of the parts in this surgical system will be manufactured using additive manufacturing.
Hay likens the process to building a tree. "It's a lamination process, with metal being deposited layer by layer," he says. "Each layer has a different profile, and you literally start growing a part like a tree with this technology," he explains. "Unlike machining, which is a subtraction process, this is an additive process. One big difference with this technology is that you are able to capture geometry that you couldn't mill."
Kamleiter of C&A Tool describes the difference between traditional manufacturing methods and the additive process as a very basic one. "Before, we used manufacturing-driven design that was dictated by the manufacturing tools we had," he explains. "By contrast, additive manufacturing is design-driven."
Manufacturers are leveraging additive manufacturing to handle relatively limited production runs of particularly difficult product designs. A good example is Kelly Manufacturing Co., which makes a variety of general aviation instruments -- air and electric-attitude gyros, directional gyros, turn-and-bank indicators, tachometers, gauges, voltage warning systems and more.
Kelly had a turn-and-bank indicator that provides the pilot with the rate of aircraft turn. A crucial piece of the M3500 is the toroid housing containing the coil used to power the gyro at the instrument's core. In the past, the housings had been made of urethane castings. But using this method of manufacture, it was difficult to maintain the tight dimensional specifications for housing height, and manual sanding was necessary to remove unwanted elements introduced in the casting process. Another issue was that new tooling had to be made at considerable expense whenever a new design was introduced. What's more, the delivery lead time to produce 500 castings was three to four weeks.
