Large elongated shape tool created using AM technology

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A collaborative effort between Spirit AeroSystems, Inc., Techmer PM, and Thermwood Corporation, produced what is believed to be the largest extendable shape tool ever 3D printed. At 6.5 feet wide by 15 feet long, the instrument’s design extended the capabilities of additive technology in several directions.

It was determined that a carbon-fiber-filled polycarbonate would provide sufficient strength to withstand the forces used in the stretchable form process. However, unlike traditional lubrication methods, Techmer PM blended a new polycarbonate formulation that contained an internal lubricant in addition to carbon fiber, eliminating the need for any additional lubrication.

The tool was printed using Thermwood Corporation’s LSAM 1020 dual gantry print and cut system. Although this machine is equipped with vertical layer printing and could have printed the tool in one piece, as it is necessary to wait for each printed layer to cool sufficiently before adding the next layer, it would have taken 58 hours of continuous printing to produce one. one-piece tool. Instead, they decided to print the part in four sections, two at a time for a total print time of 29 hours and 20 minutes, cutting the print time in half. Printing these four parts required 3,613 pounds of Techmer PM’s polycarbonate material.

The four parts then had to be machined and assembled. All surfaces of the parts, except the front work surface, were then machined into place. The holes in the center of each side are for center of gravity brackets used for handling parts during assembly.

The matched faces were then machined flat, except for the slightly raised protrusions which ensured adequate spacing for the adhesive. Adhesive is only part of a multi-component approach used to permanently and securely bond highly accurate and precision surfaces to each other.

In addition to the adhesive, bolt holes and slots have been cut into the back of the stretchable tool parts, which allow you to screw the parts together. Alignment holes and countersunk holes were machined in the center sections of the tool.

The 6-inch long alignment pins for these holes have been machined with adhesive channels, providing not only alignment between the parts but also an additional layer of permanent fixation.

The next step in securing used brackets, positioned within the structure near the front surface, which were secured using tense aircraft steel cables, holding the front surface of the four parts of the large extendable form firmly together.

The parts were then assembled. Each part is relatively heavy, and due to the relatively short open time of the adhesive, a limited amount of time was available during assembly to apply the adhesive and secure the parts securely. The parts had to be joined, while they were aligned within a few thousandths of an inch, and they had to be matched absolutely evenly. This was quite simple using the Vertical Layer Print table mechanism installed on Thermwood Corporation’s LSAM machine.

The parts were then carefully assembled by hand. Subsequently, one part was fixed to the machine table and the other to the mechanism that moves the vertical table. The vertical table drive then moved the parts about 20 inches. The adhesive was applied and the vertical table mechanism put the parts back together: square and perfectly aligned.

While this is only a first step and further testing and data gathering is required, it demonstrates that it is possible to produce large, 3D printed stretchable composite tools using currently available materials and equipment.

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