CompositesWorld

OCT 2017

CompositesWorld

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47 CompositesWorld.com fiber is supplied by Hexcel (Stamford, CT, US). e two beams are connected at each end by a 16-inch/406-mm carbon fiber composite beam, similarly constructed. Total width of the gantry is 32 inches/812 mm. Mounted on each long beam is a steel rail, on which rides the z-axis carrier and the z-axis arm (see the photo on p. 46). e z-axis arm traverses the gantry supported vertically within the z-axis carrier, a tapered carbon fiber box with a 32-by-32-inch (812 by 912-mm) flange at its base (photo above), which rides on the y-axis rails. e z-axis arm sits in and is actuated through the carrier by a servomoter mounted at the top of the z-axis arm (see drawing, p. 45). Bolfing used the same sandwich architecture on the z-axis carrier and z-axis arm — core surrounded by UD and woven carbon fiber. And, like the gantry, all of the layups are infused with epoxy supplied by Pro-Set Inc. (Bay City, MI, US) and Gurit (USA) Inc. (Bristol, RI, US) through distributors Revchem Composites Inc. (Bloomington, CA, US) and Fiberglass Supply (Burlington, WA, US). Bolfing also built the molds for the gantry parts from carbon fiber/epoxy composite, laid up on a Coastal Enterprises Co. (Orange, CA, US) 10-lb/4.5-kg urethane tooling board pattern. Cure is provided by Bolfing's in-house-built, gas-fed oven, which features an adjustable enclosure, designed to enclose a space 4 ft/1.2m wide and 8-24 ft (2.4-7.3m) long. A distinguishing design feature of the z-axis arm, says Bolfing, is the fact that its actuating equipment — motor, wiring, etc. — is CFRP Gantry Components encapsulated inside the arm, protecting it from dust generated during the machining process. And to further ameliorate dust, Bolfing applies an anti-static spray to the z-axis arm's exterior. Able performer, in demand e z-axis arm on the cgr-series has a downward travel limit of 6 ft/1.8m, the gantry is 12 ft/3.6m long and the x-axis metallic frame is available in lengths of 10-35 ft (3-7.62m). Bolfing says the machine's accuracy, over 27 ft/8.2m, is ±0.0625 inch (±0.15875 mm). Further, he claims, "No other machine has travel as large for such a small footprint. It makes excellent use of space." e machine ranges in price from just US$80,000 for the smallest foot- print, to US$160,000 for the largest. In operation, the cgr-series machinery is more accurate, travels more smoothly and performs high-detail shaping better than Bolfing expected. Further, he anticipated that 14-lb/6.35 kg foam would be the densest the cgr-series could handle, but he reports that the machine "cuts through 20-lb [9-kg] foam like it's nothing." Bolfing sold three machines before the first one was completed ("which is pretty scary") and he delivered eight in the first year. Four more will be installed this month. Many, he says, are being used by customers 24/7 in lights-out operations and have performed without any problems. He is sufficiently confident now that his design and workmanship are sustainable that he is evaluating integration of other technolo- gies to be offered with the machine, including a 4-axis rotisserie, a touch probe, a laser scanner, an additive manufacturing system and a fiber/tape placement head. Most of all, however, Bolfing wants to keep his system affordable and, therefore, easily accessible to small and start-up businesses that desire versatile, accurate, durable CNC technology. "In our business, most of your money is made in meeting critical dead- lines," he contends. "And you need affordable, big machines to do multiple operations to meet those deadlines." Jeff Sloan is editor-in-chief of CompositesWorld, and has been engaged in plastics- and composites-industry journalism for 23 years. jeff@compositesworld.com Read this article online | short.compositesworld.com/Autoscale Facilitating fast z-axis positioning The z-axis carrier features the same carbon fiber/epoxy construction as the gantry. The lightweight z-axis arm passes through the carrier and can be actuated up and down quickly by a servomotor attached to the top of the z-axis arm.

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