In the recent past, Thermwood has already 3D printed a full-size pattern which was used to produce production sports boat hull molds. Much larger vessels such as yachts, however, require a different approach. In these instances, it is desirable to print the yacht hull molds directly rather than print a plug or pattern from which a mold is made. Working with an undisclosed marine industry collaborator, Thermwood has printed a scale model of such a hull mold to test and validate the process.
Printing the yacht hull molds
The 1/7th scale test mold for this project is approximately seven feet long (the full-size hull is approximately 50 foot). It was printed from 20% carbon fiber filled ABS, using Thermwood’s LSAM additive manufacturing machine. Six separate pieces of different lengths, the longest two, each being over seven feet long, were printed concurrently using LSAM’s Vertical Layer Print capability. Printing required about 30 hours.
The ability to simultaneously print multiple parts of variable heights highlights the flexibility of both the vertical print process as well as Thermwood’s LSAM Print3D slicing software. The parts were then trimmed on the same machine and assembled into two mold halves. Thermwoods technology has also been tested and used for aerospace and automotive applications.
The tool includes a deep undercut at the transom, so the finished mold needs to be two pieces, split down the middle. These mold halves are clamped together for layup and then separated to remove the finished hull after curing.
The emergence of large format 3D printing technologies such as LSAM has been made possible by the availability of affordable composite chopped fiber composite pellets such as those introduced by SABIC. The presence of the fiber reinforcement material allows to control material deformation during deposition and thus leads to better dimensional stability.
Molds for hulls that are longer than fifty feet will be printed in multiple sections, assembled for hull layup and then disassembled to remove the finished part. The test tool printed here simulates that assembly and disassembly process. The tool printed in this program will be tested using production materials in a production environment. Thermwood continues to work on methods and techniques needed to refine this into a production-ready process.
Thermwood believes that the marine industry will benefit significantly from emerging large-scale additive manufacturing technology and that this project is a significant first step toward the direct production of large vessel tooling.