Development of a supervision system: towards closing the control loop in 3D printing systems

3D printing has been seen as the future of manufacturing due to the many advantages it offers, such as obtaining complex geometries and the possibility of fully customisable parts. However, errors can occur and go unnoticed until due to the lack of closed-loop control. Low-end printers usually suffer more from these failures caused by interruptions in the material flow. To address these, the work reported takes an initial approach towards closing the loop: supervising the extrusion nozzle, detecting material flowing out, and correlating it to the printing process to determine if it is occurring when it should. The supervision is performed with a camera at the extrusion nozzle, the images are processed, and the printing process stops when a failure is detected, enabling to resume without wasting the partially printed part. A comparison of the mechanical performance of the resumed printed parts and an uninterrupted printed part is carried out to better understand the effects of this approach. Although the system is developed for fused-filament printers, closing the loop on the printing process would benefit all additive manufacturing processes; therefore, the work proposed is seen as a test case that can later be scaled to other printing technologies.