Thermwood has developed LSAM, a large-scale additive and subtractive manufacturing facility, and has successfully printed tooling molds in the field that can be used in aerospace composite molding, demonstrating its ability to manufacture low-cost, fast-response composites.
As a manufacturer of large part additives, Thermwood has developed a near-net-shape method for manufacturing parts, first using high-speed 3D printing to produce a slightly larger size than the desired part, and then cutting it to the final size and shape. In 2017, the company signed a formal cooperative research and development agreement with the Eastern Fleet Readiness Center of the Naval Air Systems Command to collaborate on the development of large-scale additive manufacturing technology. In 2019, Thermwood partnered with the U.S. Air Force Research Laboratory (AFRL) and Boeing on a research project to produce low-cost, fast-response molds using additive manufacturing, and Boeing's Auburn facility also has a Thermwood large-scale polymer additive manufacturing system with a 6m print bed that can print parts 3m wide, 6m long, and 5 1.5m high. In 2021, Purdue University established the Thermwood LSAM Research Lab for large-scale 3D printing.
LSAM composite material additive and subtractive equipment and key technologies
LSAM is a large-scale thermoplastic composite additive and subtractive manufacturing equipment, its standard model is equipped with a fixed table and a movable gantry, on which an extruded 3D printing head and a traditional milling head are installed, so that the parts can be manufactured on the same equipment, avoiding the errors caused by re-fixing the parts.
The LSAM 1540 unit has a double gantry structure (table size 15 ft× 40 ft., 4.5 m × 12 m)
LSAM uses a two-step "near-net shape" production process. Parts that are slightly larger than the required size are first printed at high speed, and then trimmed to their final size and shape through finishing machining. This is the fastest and most efficient way to 3D print large structures. With LSAM equipment, printing and finishing can be done on the same machine. With a double gantry structure, one part can be 3D printed and the other part milled at both ends of the table at the same time, further improving efficiency.
LSAM equipment can process almost any thermoplastic composite part, including high-temperature materials such as PSU, PESU and PEI, which are molded at high temperatures, and are ideal for molds and tools that must be molded at high temperatures. The system integrates a liquid cooling system for drying and conveying polymeric materials to maintain temperature control of vital systems, which is particularly important for processing high-temperature materials, enabling the production of high-quality, fully integrated products. These materials are also primarily used in the production of molds and tools, with the majority being used in aerospace and industrial production applications.
LSAM 3D printed and milled the two parts, respectively
The key technologies of LSAM include the following:
The first is the advanced printing system design. Most of the heat of the printhead extruder comes from the heated barrel rather than the friction between the screw rotation and the printing material, which heats more evenly than traditional designs and does not require the replacement of screws to process different composites, the printhead uses a special alloy to support processing temperatures up to 450°C, the polymer melt pump is servo-driven to control the flow to form a uniform output, its uniquely designed pressure wheel allows for no gaps between the printing layers, and the bottom of the part is printed onto a special adhesive plate to eliminate cooling stress and part warping.
Screw extruder
The second is a powerful control system. LSAM integrates a control system capable of monitoring and adjusting real-time temperatures, automatically handling extrusion and print speeds. When the material profile is loaded, all parameters of the polymer, such as zone temperature and pressure limits, are automatically set, and the control system automatically synchronizes the output of the melt pump with the speed of the machine's movement, ensuring absolute dimensional accuracy, regardless of whether the machine is accelerated or decelerated.
Thermostat pressure wheel diagram
The third is the process software suitable for additive manufacturing of large parts. With functions such as corner pullback compensation, it can realize the programming of complex parts and automatically adjust according to the printing characteristics of the LSAM equipment.
Special adhesive board
LSAM's unique printing system produces high-strength, fully fused, vacuum-sealed, virtually void-free parts. It is not a laboratory or demonstration machine, but a full-fledged industrial additive manufacturing system that is fully capable of producing large components.
Boeing verifies LSAM viability
Boeing Research & Technology Laboratories partnered with Thermwood on a U.S. Navy-funded project to prototype composite tooling for autoclave processes using large-format additive manufacturing to validate the viability of a low-cost, rapid alternative to traditional tooling manufacturing methods. The autoclave needed to be durable enough to withstand multiple curing cycles of 180°C and 586Kpa.
The size of the autoclave is about 1m x 1m x 0.4m, Boeing uses LSAM1020 equipment and carbon fiber reinforced PESU material to print parts, the most popular uses 277kg of material, it takes 7 hours and 26 minutes to complete the printing, and the milling head is replaced to complete the final processing within 53 hours, and the size and surface quality of the tooling meet the design requirements. After several autoclave process cycle tests, the vacuum retention, dimensional stability and high temperature durability of the tooling can meet the requirements. The project demonstrated the ability of LSAM equipment to perform additive and subtractive manufacturing on a single platform for composite tooling, resulting in cost savings of approximately 50% and a 65% reduction in manufacturing cycle time compared to traditional manufacturing methods.
LSAM equipment prints composite tooling that can be adapted to the autoclave process
In addition, Thermwood successfully printed a 3.6-meter-long Boeing 777x trimming fixture using patented Vertical Layer Printing (VLP) technology, which took approximately 43 hours to fabricate additive-subtractive materials, demonstrating the LSAM equipment's ability to manufacture large-scale, low-cost and rapid applications. At Boeing's Auburn plant, a Thermwood large-scale polymer additive manufacturing system with a 6m print bed was also installed.
Trim fixtures for the Boeing 777x
Composites manufacturing is a strategic technology for the platform of the future, and the development of more cost-effective tooling solutions will greatly benefit manufacturing. With its patented 3D printing technology and integrated design ideas of additive and subtractive materials, Thermwood provides the ability to complete 3D printing and finishing of parts on a single machine, with the advantages of low cost and short lead time. As a result, the company has developed the industry's largest composite thermoplastic additive manufacturing system for applications in industries such as aerospace, military and defense, marine and shipbuilding.
Source: Frontiers of Additive Manufacturing Technology
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