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Case Study / Topic 10 MoldMaking Technology —— AUGUST 2016 Case Study / Machining time out of each job while still maintaining tight tolerances and the correct stack heights in order to achieve precise inter- changeability." Multitasking in One Setup The Okuma LB3000 MYW is a "live-tool lathe," meaning it is a CNC turning center that also has milling capability, allowing machinists to hard-turn com- ponents and eliminate most grinding operations. For exam- ple, each cavity stack within Trifecta's closure molds typically consists of three to five parts (the core, cavity and other com- ponents). Before purchasing the Okuma, the company's machinists would first have to turn the round parts, then grind inner and outer diameters, and then mill water lines using one of the company's Hurco CNC mills. The grinding process alone could take an extra hour to two hours per part within each cavity stack, depending on the complexity of the part, West says. "A time-savings aspect for us is the ability to eliminate the OD/ID grinding process and instead hard-turn cores as much as possible," he says. "You cannot turn everything, but we have been able to reduce grinding by 90 percent on a lot of the parts we make, and we are still able to hold close tolerances." An additional assembly from WTO GmbH also enables the Okuma to perform gear-hobbing functions to machine unscrewing core details and other components. "The gear- hobbing ability allows us to completely finish most parts in one setup," West says. "Previously, unscrewing spindles used to have gears that were inserted, or they had to be sent out to be gear-hobbed. When these gears were needed, the hobbing process was usually outsourced, and it could take two to three weeks before the parts came back. We save a tremendous amount of time over the course of such a project by being able to hob the gears right on the spindles in house now." The Okuma-designed, high-torque PREX synchronous motor also enables the machine to make heavy cuts in diffi- cult-to-machine materials, including tool steels like stainless, hardened and high-carbon. This, combined with Y-axis-offset turning and a main spindle and live subspindle located within a double toolholder, enable the completion of both rough and This part for an unscrewing mold also was machined on the Okuma lathe. According to Bret West, the machine's ability to hard-turn inner and outer diameters and gear-hob the components in one setup results in time savings of at least two hours per part. This core, made of H13 steel hardened to 48-52 HRC, and stripper ring stack, made of S7 steel hardened to 55-57 HRC, were hard-turned on the lathe, but because it can machine to tight tolerances, grinding was not required. This saved the shop one to two hours per stack in machining time.