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12 MoldMaking Technology November 2014 Case Study / Machining By Matthew Danford For intricate details and finishing work, 5,000 rpm just wasn't cutting it. It's not as if the toolroom at EVCO Plastics' headquarters facility didn't have faster spindles at its disposal. The Makino VMCs that handle most of the milling at the DeForest, Wisconsin, operation can achieve 20,000 rpm. However, speed wasn't the only limitation. Weight and size capacity were often the chief factors driving the company to out- source, says Jim Kollath, corporate tooling manager. Better supporting EVCO's global plastic injection molding business would require equipment with the versatility to handle both heavy hogging and toler- ances ranging to ±0.0005 inch on molds as heavy as 16,000 pounds. With a larger work enve- lope and a spindle speed matching that of the shop's smaller workhorse machin- ery, the Bridgecenter-8F from Kitamura has fulfilled both requirements. Other ben- efits cited by Phil Anderson, toolroom supervisor, include less operator intervention and additional design freedom for larger molds. In fact, EVCO was pleased enough with the double-column, bridge-type machining center that it opted for another, larger model from Kitamura, a Bridgecenter-10, when it moved to expand size capacity for a second time. No Compromises for Large-Mold Machining The two machines have not only expanded the range of work that EVCO can keep under its own roof, but also ensured that work can be processed as cost- effectively as possible. A Critical Supporting Role Regularly processing core and cavity blocks weighing as much as 8,000 pounds apiece is new ground for the shop's 12-man team. Yet, such parts aren't all that large in the context of the overall operation, Kollath says. The 6,500-square-foot tool- room is just one small facet of a 900-plus-employee company with nine injection molding facilities—four in Wisconsin, one Two double-column bridge-type VMCs reduced this operation's reliance on outside suppliers without requiring trade-offs between power and precision. Although the Kitamura Bridgecenter-8F is well-suited for removing large amounts of steel as quickly as possible, EVCO didn't have to sacrifce power for speed. Here, Larry Dean, moldmaker, takes advantage of the machine's step-geared spindle to perform high-speed rib cutting in a pre- hardened, P20 steel mold that will run in a 1,500-ton press. Images courtesy of EVCO Plastics.