Turbocharging Impeller Production

When Turbocam (www.turbocam.com; Dover, NH), a supplier of turbo machinery parts for ground and aerospace transportation applications, was tasked with producing a diesel engine turbocharger impeller for a customer, it installed a new production cell.

When Turbocam (www.turbocam.com; Dover, NH), a supplier of turbo machinery parts for ground and aerospace transportation applications, was tasked with producing a diesel engine turbocharger impeller for a customer, it installed a new production cell. Each cell consists of two five-axis Chiron FZ08KSM machining centers each fitted with a Siemens SINUMERIK 840D CNC control from Siemens Automation, Machine Tool Business (www.siemenscnc.com; Elk Grove Village, IL), an ABB material-handling robot, and a 250-unit workpiece carrousel. According to Andrew Hussey, engineering manager at Turbocam, "Aluminum stock"—the 4 x 4-in. impellers are made of type 2618 aluminum—"is turned on CNC lathes, then loaded onto the carousel. The CNCs on board the machining centers interface through our PROFIBUS network to the robot controller and the carousel to maintain workpiece load/unload cycles on the machines."

Because of the complex geometry of the parts, Hussey says that there could have been a problem in machining: "The high speeds"—the Chirons operate at feeds as high as 75 m/min, accelerate at up to 2 g, and operate at a spindle speed of 27,000 rpm—"and five-axis movement can create non-linear machine motion that affects the accuracy of the cutting; the CNC/drive package helps smooth out those kinematics." In addition to which, the programming software, CAMplete TruePath from Camplete Solutions (www.camplete.com), takes APT or CL data and factors machine motions and the design intent so that the tool path meets the requirements. They've found that average runtime is reduced by more than 20%, even though tolerances are ±0.002 in. It should be noted that vibration motions, spindle accelerometers, and laser position detectors are onboard the machines, helping to assure accuracy.

"We'd put our productivity curves up against any shop in the country," Hussey says.