Modern Machine Shop

DEC 2016

Modern Machine Shop is focused on all aspects of metalworking technology - Providing the new product technologies; process solutions; supplier listings; business management; networking; and event information that companies need to be competitive.

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mmsonline.com December 2016 MMS 71 FEATURE A bird's-eye view from a high balcony is the closest look most visitors ever get at Tube Hollows International's 20,000-square-foot main production area, and that's for good reason. The 27 gundrills turning exotic-material bar into highly concentric, uniform-walled tubing, of ten with extreme length-to-diameter ratios, aren't standard models that anyone can purchase. They're the company's own design. That's not to suggest that these are "magic machines," says Dave Morse, general manager, explaining that what the com- pany is really trying to protect is the proprietary process that created the need for this customized machinery in the first place. "For us, everything starts at the center," he says about the 50-employee company's "bore- centric" approach to drilling. Leveraging this technique, machinists at this specialist manufac- turer in Windham, Maine, can locate a tube's inner diameter (ID) in relation to its outer diameter (OD). That's a stark contrast from the common approach Active Scanning Makes Hole Inspections Whole Complete form measurement data on complex bore interiors helps this specialist in precision tubular components hollow out an even more competitive niche. BY M AT T DA N FO R D Tube Hollows chose a large machine from Zeiss' Contura line, a G2 with an XYZ measuring range of 1,000 by 2,100 by 600 mm, to incorporate the longest tubular parts for newer customers. Person- nel like quality manager Travis Ingram, shown here, rely on the active-scanning Vast XT Gold measuring head to accommodate the lengthy stylus extensions required for deep bore IDs. All images courtesy of Tube Hollows International. of drilling a straight hole, centering on the ID and then turning down the OD, Mr. Morse explains. In addition to facilitating total indicator runout (TIR) of 0.008 inch or less on stock as long as 25 feet, borecentric provides savings on costly materials like titanium and nickel-based alloys, and it enables drilling or reconditioning shafts with pre-machined OD features. Nonetheless, he insists that the company could never realize the full competitive potential of borecentric drilling without advancing its metrol- ogy capabilities to a similar level as its machining capabilitie s. A ndrew March, te chnical sale s engineer, says bore gages and other handheld instruments simply aren't sophisticated enough to ser vice Tube Hollows' newest customers: aerospace and energy industry manufacturers that demand more than just straight, uniform- walled tube. Scanning on a coordinate measuring machine (CMM) has proven essential to providing complete geometric dimensioning and toleranc- ing (GD&T) form data for the complex, feature-rich interiors of tubular parts like turbine actuators and landing gear components. However, not just any scanning head would do for the company's new Contura G2 CMM, purchased from Zeiss Industrial Metrology this past June. Measuring recessed slots and notches; protruding geometry like ribs and splines; mul- tiple, contouring diameters with stepped-radii transitions; blind bore bottoms that are perfectly

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