Final Design

Fiber-Reinforced 3D Printer using a KUKA 6+1 axis robotic arm

The finalized project design consists of two main components that attach to the milling box that is currently mounted on the KUKA robot, the spool/component mount and the extruder tool. The continuous fiber and the plastic filament are held on separate spools mounted on the sides of the mounting box mount. The filament is pushed through a PTFE tube connected to the extruder by a stepper motor, similar to standard 3D printers. The continuous carbon fiber is pulled by the motion of the printing head after being threaded through the nozzle and adhered to the printing baseplate. The plastic filament and continuous fiber proceed to be combined into a single channel through the hole on the side of the extruder tip. The plastic filament is then melted by the heating element, coating the continuous fiber before finally exiting the extruder tip. The spool and component mount is manufactured from aluminum and connected to the M8 threaded holes on the top of the KUKA milling head. This design is straightforward, durable, and easily attached or disassembled.

The extruder tool uses a standard metal J-head bowden extruder with a heating block heated by a heating cartridge. An M10 PTFE quick-release connector is screwed in the extruder for the tube with the PLA filament can connect. The extruder itself is connected to an aluminum adapter, which can be inserted into an ER-40 collet at the end of the KUKA milling head, by an aluminum bracket. The extruder tip has a small hole on the side for the carbon fiber to be embedded with the PLA. The tool adapter design allows quick tool changes on the KUKA robot and is able to utilize the robot’s laser centering function for higher point accuracy.

The on-board electronic component design eliminated possibility of loose wires interfering with 3D printing components or KUKA movement paths. The 12V 360W power supply was able to power all electrical components, which included the stepper motor, heating cartridge, component drivers, and Arduino controller board. The Arduino code used a task scheduling system to implement pseudo multi-threading for controlling both the stepper motor speed and heating cartridge temperature simultaneously.

The spool mount fits well on the head of the KUKA. With a slight inward bend, it allows the sleeve to be held with friction. Additional M8 machine screws secure the mount from the top, attaching directly to mounting threads located on the milling head. The spool mount can withstand the full motion and speed of the KUKA robot arm during fast travel. The electronics, including the heating element and stepper motor, all work well in conjunction and are able to extrude the PLA filament at appropriate speeds. The extruder was easily integrated due to the ER40 quick change collet. The tip is concentric with the axis of the milling motor, allowing the PowerMILL path software to use the tool without needing to input exact geometry.

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