CNC router manufacturer Thermwood (Dale, Indiana / USA; www.thermwood.com) has launched a programme to develop a 3D additive manufacturing system capable of making large carbon graphite reinforced composite thermoplastic components. The systems utilise a "near net shape" approach where a custom-built vertical, integrated extruder deposits or "prints" carbon graphite filled thermoplastic material to quickly create a structure that is close to the final shape. Once it cools and hardens, it is then five-axis machined to the final shape.

Developed with extrusion specialist American Kuhne (Ashaway, Rhode Island / USA; www.americankuhne.com), the process minimises three challenges of conventional 3D printing, particularly for large parts: uneven cooling, material waste and extensive post-print processing. The systems will be based on Thermwood’s "Model 77", semi-enclosed, high wall gantry machine structures, which are currently offered in sizes up to 18 m in length.

The initial development machine, which is nearing completion, can make parts up to around 3 m x 3 m x 2.5 m high. It is equipped with an integrated, vertical 4.5 cm diameter extruder and support equipment capable of processing over 45 kg/h. Despite the relatively heavy weight of the extrusion system and head, which are both mounted on and move with the machine, the machine generates impressive performance with high acceleration rates and high feed rate capability, the companies said.