A derivative of its barrier coat and core materials, a specially formulated syntactic from ITW SprayCore (Clearwater, Fla., U.S.A.) now serves as the tooling surface for Vectorworks Marine Inc.'s (Titusville, Fla., U.S.A.) new toolmaking "shortcut" called Limited Production Tooling (LPT).
Production timeframes and budgets, even for luxury yachts, have diminished in recent years. Tooling specialist Vectorworks sought ways to move its customers' hulls and other parts through prototype to production faster by shortening the traditionally step-intensive process: creating plugs, building production molds, pulling prototypes, updating the molds and pulling plugs, then creating production molds from the plugs.
For the shortcut concept, says Vectorworks CEO Jeffrey Gray, "we use a conventional steel substructure, and a loft with a moderate offset from the final surface." The loft is overlaid with plywood sheeting, then undercut in a monolithic foam layer and stabilized with a fiberglass sprayup laminate. Finding the right surfacing material took some trial and error. "We tried a couple of tooling putties, but either they weren't cutter friendly or would chip or give us an inadequate finish," says Gray. Familiar with SprayCore's barrier product, he suggested using its materials as tooling putties. SprayCore responded with 2000-HS: the same resin-base as its core replacement, but with "cutter-friendly" fillers. Applied with Binks (Glendale Hts., Ill., U.S.A.) spray equipment, the material builds to 70 mils per pass, even on vertical surfaces, without sag, sets in 5 to 6 minutes and cures in 15 to 25, often enabling a technician to begin a new coat as soon as the previous coat is fully applied. Gray reports that the cured material is extremely hard, but mills exceptionally well. "The syntactic putty we used previously consumed multiple cutting tools per mold," he explains. "SprayCore doesn't contain the abrasive additives that once destroyed our cutting tools." Now, even the largest plugs can be shaped with a single cutting tool, and Vectorworks' three 5-axis machines can run at faster speeds, which reduces milling time and improves mold finish. "Our LPT molds produce a plug so high in quality that it can also serve as product prototype," Gray adds. "The boat manufacturer can use that prototype for testing or to get to a show, then make design changes directly on the prototype/plug (or a second or third part pulled from the LPT mold), and pull their own production molds from it."