Computer Numerical Control (CNC) machining consists in using computers to automate the control of machine tools that manufacture parts into desired shapes by means of material removal through cutting tools. The desired shapes to manufacture are coded in G-code programs that describe the geometries of the desired parts and the trajectories of the tool to achieve them. Changing the part to be produced is as simple as modifying the lines of the manufacturing program, which makes this a flexible technology especially appropriate for manufacturing small to moderate series of different geometries.

CNC programming is typically taught at undergraduate mechanical engineering courses. In these courses, fundamentals of CNC programming are usually studied with focus on the most typical machines, which are lathes and milling machines. CNC programming is initially taught on paper during theoretical lectures, but due to its practical nature, it is best learned and consolidated by coding manufacturing programs and testing them on machines. Ideally, it would be best to test manufacturing programs on real machines. However, this has some limitations in educational contexts, namely: these machines are quite expensive and often educational institutions cannot afford many of them, they are dangerous to use for inexperienced students who are learning for the first time, and it would take too much time and raw materials to allow all students to test their programs on real machines. As a consequence, simulation emerges as a cheaper, safer and more efficient intermediate substitute for testing manufacturing programs, at least as a bridge between theory and real-world machines.

There exist many educational and training virtual simulators to practice CNC programming. Typically, these simulators consist of a control interface that emulates the control panel of a real machine, with a display where the students can type the programming code as they would on a real machine. Then, the manufacturing program can be tested on a virtual environment, which shows realistic animations of the motion of the machine while describing the trajectories that shape the initial raw part into the final desired geometry. Nevertheless, most of these training simulators focus on lathes and milling machines, typically limited to two and three-dimensional motions. Although these are the two most usual CNC machines in industry, there exist advanced machines capable of executing more complex motions that achieve the manufacturing of products with intricate shapes. This is the case, for instance, of Parallel Kinematic Machines (PKM) used as CNC machines. PKM are robotic devices where the cutting tool is controlled by two or more kinematic chains mechanically arranged in parallel, which results in stiffer motions and more accurate operations.

Considering the scarcity of training simulators to practice advanced CNC programming with PKM, this abstract presents a new training simulator that allows students to type and test G-code programs on a simulated Stewart hexapod, which is one of the most versatile and well-known PKM. The proposed simulator shows graphical animations of the hexapod and its tool, as well as its interaction with the raw parts to simulate the process of material removal that carves the desired geometry as specified by the program coded by the student. The presented simulator is useful for teaching and learning CNC machining of advanced shapes with PKM.

Keywords: Machining, Manufacturing, Training, Simulator.