Even though large scale additive manufacturing is becoming more common, it’s still no less impressive to see what it can produce. Massive objects can be 3D printed in very few or even in one piece, and when you add CNC machining into the equation, you get an even more streamlined manufacturing process. That’s what Thermwood Corporation did last year when it introduced its Large Scale Additive Manufacturing, or LSAM, machine.
LSAM is a double gantry machine with a print gantry, featuring a build area of 10 x 5 x up to 100 feet, and a trim gantry, featuring a five-axis CNC router. The print gantry 3D prints a part at slightly larger than its final size, then the trim gantry machines it down to that final size while finishing the surface at the same time. Thermwood has showed off the LSAM’s ability to quickly create strong, tough parts, and now the company has unveiled a project that shows off the machine’s capability for producing extremely large items, as well.
Thermwood recently worked with Techmer PM and Marine Concepts to build a boat. Several boats, actually. Boat hulls are often made from fiberglass molds, and the three companies wanted to see what would happen if they 3D printed the pattern for a boat hull mold rather than manufacturing it with traditional methods.
The team used Techmer PM’s Electrafil ABS LT1 3DP material, which has shown itself to be successful when used in marine applications, especially when 3D printed and machined with LSAM technology. The pattern was printed in six sections: four main center sections with walls about an inch and a half thick, as well as a solid transom and bow. The parts were pinned and bonded together using a Lord plural component urethane adhesive, for a solid piece that was, as most objects printed with LSAM are, slightly larger than the final product would be. LSAM then machined the pattern as one piece, taking it down to its final size.
The final boat hull pattern weighs about 3,000 pounds. It took about 30 hours to print and 50 hours to machine. Thermwood used a demonstrator LSAM with a print table of 10 x 20 feet and a print head capable of printing close to 200 pounds per hour when using this specific Techmer material. LSAM also offers larger machines, as well as print heads with higher print capacity. The strong, sturdy pattern was used to pull a fiberglass mold, which would then in turn be used to create the final boat hull.
The project was part of a proof of concept joint evaluation program, and the finished pattern was displayed at the AM2017 Additive Manufacturing Conference in Knoxville, TN. The entire process, from printing and trimming to finishing and coating, took less than 10 days, a remarkable reduction in time. The process of 3D printing and milling the pattern proved to be not only faster but more economical and practical, and the group wants to experiment further with 3D printing and boat hulls.
For one thing, Thermwood wants to try directly 3D printing boat hull molds rather than just the patterns for larger boats and yachts, though these large boat hulls will need to be 3D printed and machined in sections. It’s possible that 3D printing them may also allow for the incorporation of integrated cooling channels for air or liquid. Another idea involves printing one pattern and flipping it to allow the production of both a hull and deck mold. Any of these options would bring down cost and build time by a great deal.
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