SkillMill – 60-year-old milling machine with digital twin

Green enamel and weighing 1.5 tons, it's a machine like the thousands found in German companies. But Friedrich Korradi's milling machine can't be compared to that. A few hardware modifications and, above all, a digital twin enable previously unimaginable enhancements, time savings, and precision. Furthermore, the digital twin opens the door to the production of the future.

Andreas Wagner from the RPTU Kaiserslautern-Landau has been toying with the idea of ​​retrofitting for some time, ever since the milling machine was delivered two years ago. His idea: to convert it so that it can operate skill-based. He is pursuing his doctorate on the topic of skills and sees retrofitting as a cost-effective option for combining the latest technologies with older machines.

"Many companies don't take advantage of the possibilities offered by Industry 4.0 technologies because they think they'll have to purchase new machines," Wagner explains. "I want to show that this isn't true. Digitalization can take hold everywhere and unleash its efficient effectiveness."

What was changed on the milling machine?

The machine was equipped with feed motors, a digital twin, and a CNC control system. The milling machine's capabilities (skills) can be accessed as skills, such as milling rectangular or circular pockets. They can be controlled and parameterized via a uniform OPC UA interface. Before work begins, the digital twin calculates, among other things, costs and energy requirements, plans the trajectory, and checks it for collisions. It thus assumes the role of a CAM system and returns information that can be used, for example, to create a quote. The digital twin thus helps to automate and optimize the entire planning process.

What additional capabilities does SkillMill now have?

Geometric features of a component can be machined directly from CAD using the latest Industry 4.0 paradigms. This saves time-consuming programming work. When searching for suitable machines for a specific job, SkillMill, like all other machines with similar capabilities in the machine park, automatically responds according to the skill-based approach. To ensure that a skill can be executed with its specific parameters, the digital twin performs a feasibility check in advance to verify the feasibility of the job.

Why is the SkillMill exemplary for other machines at Bownfield?

"Old machines are still standing around in production halls today," Wagner says.

This example shows that even such machines can be transferred into the future through retrofitting.

"It would be conceivable for them to be integrated into data rooms via the digital twin, as is planned with Gaia-X or Manufacturing-X," Wagner continues. "Then the machine could offer its skills there, which could then be rented by other companies. This would lead to it receiving new orders and being used more frequently." Using the digital twin, the machine can provide an inquiring customer with precise information about the working time, CO₂ footprint, energy consumption, or price. The digital twin thus opens the door to the production of the future.