There are numerous error-prone process steps and a lot of working time between the first sketch and the finished component: first, a designer creates a three-dimensional CAD model. She then derives a two-dimensional technical drawing from this and adds additional information: Tolerances, fits, parallelism, surface roughness and so on. It passes the CAD model and technical drawing to the manufacturer. In the case of simple components, the manufacturer makes the appropriate settings directly on the machine. For more complex geometries, however, it is advisable to load the data into CAM software, which then automatically generates machine commands. However, it is up to the manufacturer to decide which milling cutters and drills are suitable for machining the raw material and how best to clamp the raw part.

Tobias Herrmann from the Lightweight Construction Technologies department at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA has now found a way to eliminate some of these many process steps in design and production. CAD models and technical drawings are replaced by a nomenclature of nine basic characters that can be used to specify everything that a milling machine is supposed to implement. A worker writes these characters directly onto the raw material with a pen: R5, for example, stands for a rounding with a radius of 5 millimetres, F20 for a 20 millimetre wide chamfer or E10 for a milling cut-out of 10 millimetres, the exact shape and dimensions of which are specified using lines on the raw material.

A remedy for the shortage of skilled workers

There are also nine conventions, such as the fact that only lines at an angle of 0°, 45° or 90° are permitted when drawing contours and features, or that the workpiece zero point is always in the top left-hand corner from the machine operator's point of view. Once the raw material has been marked and clamped, it is scanned by a laser scanner, the characters are interpreted and a vector graphic is derived from them. Software then translates the vector graphic into machine commands (NC code) within a few seconds and creates a target component as a CAD model. The machine commands not only contain precise information about where the machine should do what with which tool, but the software also provides for tool changes. In other words, it specifies where the machine should use different milling cutters or drills.

With these features, Easy CNC, as Tobias Herrmann calls his development, would not only be a shortcut to the finished machined component, but also a means of combating the rampant shortage of skilled workers. This is because Easy CNC transfers the specialist knowledge of experienced designers and manufacturers into software commands. "The machining know-how is no longer stored in the heads of the designers and manufacturers, but in the machine and software," says the researcher.

Intermediate control should enable access to existing machines

However, there are still a few unanswered questions to be clarified before this can happen. First and foremost: How do you get access to old CNC machines? This is because existing machines are often not designed for digitization. There is no provision for external systems to access them and issue commands. Herrmann is now trying to influence the machine commands via an intermediate control system. CNC machines could then also access networks and databases. In addition, instructions and directions can be passed on to the machine operator. However, many tests on machine communication and system integration are still required to implement this.