Development of a 3 D.o.F. platform for additive manufacturing based on MIM technique

In the Mechanical Department of Politecnico di Milano a project has started to develop a new 3D printer based on a MIM, metal injection molding, technology aiming to print metal objects with different mechanical properties and with lower costs than ones printed by usual techniques. This master thesis continuous on an already started project where an automated machine for 3D printing has been designed and built based on a linear delta robot with 3 D.o.F., degrees of freedom, and a MIM extruder. The aim of the work is to develop a machine capable to provide a complete set of functionalities as usual 3D printers. In order to permit the correct study and development of this new 3D printing technology the machine must be able to print from a G-code, typical command language used for automated machines, allow a generic movement of the system, and allow the control and regulation of specific technological parameters. To reach these goals a study and a development of the mechanic and control system are done. Manufacturing tolerances on mechanical components and imprecision during assembly can lead to numerical misestimation of the geometrical parameters used in the kinematic equations of the control system. Thus a calibration method is developed to obtain the actual measures to ensure the correct positioning of the robot. The robot tructure needs to be stiffened and an adjustable plate is designed to ensure perpendicularity of the moving plate with the axis of the extruder nozzle. A control scheme with its electrical and electronics components is developed with the aim to power the system, measure correctly some key values of the machine and control it through the use of a Mitsubishi® PLC, programmable logic controller, and a motion control unit. This system is fit inside an electrical cabinet. The control programs are developed using Matlab® and native Mitsubishi® software able to analyze the object to print, either from CAD software(parsing effectively a G-code)or user generated equations, to assign a given motion law and to execute them on the final system. It's presented a CNC emulator capable to provide these functionalities taking into account the constraints of the Mitsubishi® control system as for instance the management of the internal memory. A manual control is also developed for a generic use of the machine by an operator.