Fairfax, VA -Too much time. Too much money. And too much risk. That about sums up the uncertain process of tooling up for a new product's plastic components. So when the engineers at eko systems inc. designed the high-impact-polystyrene enclosures for a new line of networked medical workstations, they decided not to use any tooling at all.
To make the three separate enclosures that house each workstation's CPU, keyboard electronics, and interface devices, eko engineers turned to Tool-Less Technologies Inc. (Mukilteo, WA). Using patented technology developed by Germany's TTK Kunststoff Technologie GmbH, Tool-less fabricates enclosures from flat pieces of thermoplastic sheet that it first runs though CNC machining and bending equipment and then solvent bonds into the final enclosure shape. It then finishes the enclosures by adding EMI shielding, fans, membrane keypads, and other secondary features. Tool-less can typically deliver production housings just two to four weeks after it receives information about the electronics design and functional requirements, according to Jim Fowler, the company's president. Contrast that lead time to the 8 to 20 weeks that hard tooling often requires.
Though it represents one of Tool-less Technology's most difficult jobs, the eko housings hit the sweet spot for tool-free production in every way that counts:
They balance cost and volume.
With projected production volumes of under 500 units per year, the workstation didn't really justify most kinds of hard tooling. Eko co-founder and chief technology officer Jim Edmiston estimates that comparable injection-molded enclosures would have had a tooling cost in excess of $350,000. "The Tool-Less enclosures cost more on a per-part basis at first," Edmiston acknowledges. But once he factored in the tooling savings, Edmiston found that the Tool-Less enclosures really cost one-tenth as much as equivalent molded boxes. Fowler adds that smaller, but still significant, savings would have resulted had eko looked at processes with lower tooling costs-such as RIM and thermoforming.
Their design changed.
"When we started, we didn't know exactly what the final product would look like," recalls Steve Lyons, eko's chief design engineer. And he cites a litany of design changes as workstation enclosures went from prototype to production. Some of the changes-like moving connectors or enlarging the recesses for labels-were relatively simple. "But they would have been costly if we had to rework steel tools," Lyons notes. Other modifications were more extensive. At one point, eko nearly doubled the size of the CPU enclosure to make way for a hotter, faster processor and add contours to the front panel.
The Tool-Less process accommodates on-the-fly design changes so easily it seems to blur the line between prototype and production parts. For changes both simple and sweeping, Lyons would simply provide a new dimensioned drawing to the engineers at Tool-Less. They would use this information to change their CNC code. Fowler says a typical CNC change costs under $1,000. "Even simple tooling changes can cost 20 times that amount," he says.
"Implementing change quickly without spending a fortune was one of the most important benefits for us," says Lyons, who adds that this capability offers value not just during the prototype stage but also as the commercial product evolves. "We use a lot of off-the-shelf electronics whose specs can change over time," he says.
They have the right features. Far from taking the venerable beige-box approach to electronics packaging, Lyons designed enclosures that have the appearance of a consumer product. The keyboard, the most complex enclosure, has a sloped front and integrates a display, a membrane keypad, and a magnetic card reader. Because of these features and the sloped styling, "the keyboard really pushes the limits of what the Tool-Less process can do," Lyons says. All three enclosures, not just the keyboard, required the Tool-Less process to incorporate the usual internal and external enclosure features-including bosses for screw inserts, mounting clips, stand-offs for the circuit boards, and offset vent holes. Thanks to a metal-filled part spray, these housings also offer EMI shielding.
They avoid design constraints.
Tool-Less enclosures have to overcome a couple of key design constraints: Their solvent-bonded joints don't meet the most stringent impact requirements. And the CNC bending process can't make compound bends-that is, those made in more than one axis. The eko workstations steer clear of both constraints. Because they will normally stay in one place, much like a desktop computer, the workstation enclosures didn't need to meet the most stringent impact requirements. "We didn't have to design the workstations to be dropped," says Lyons. And the lack of compound bends didn't present any problems because Lyons designed for the tool-less process from the beginning. "I knew not to use any compound bends," he says.
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