Together with the metal-cutting specialists at Audi Toolmaking, Vero Software GmbH has developed a new WorkNC (www.worknc.com) high-feed-rate strategy that has allowed Audi to reduce pre-finishing machining times for various press tools by up to 30%.

The new strategy has also resulted in the operating life of cutting tools being increased by a factor of three.

The tool-making department at Audi AG — generally referred to as KCU — manufactures press tools for components such as vehicle doors, engine bonnets and side panels; it is also continually seeking innovative ways to improve its machining processes.

One person deeply involved with this is Markus Brunner — a member of the Machine Technology Management team at KCU in Ingolstadt; one of its tasks is applying developments in CAD/CAM technology to optimise the tool-making process.

Mr Brunner says: “The machining of complex single parts is one of the challenges we face; and with frequent product changes, we need flexibility in our approach to machining — and efficient CAM programming.”

His main focus is on increasing quality and productivity, and for a number of years he has been working with Vero Software GmbH and its WorkNC CAM system.

“We make extensive use of WorkNC for three-axis, 3+2-axis and five-axis simultaneous milling when making our press tools. We find that it is both easy and intuitive to use, even when programming highly complex parts.

“It also offers many ways of standardising and automating machining tasks and programming them.”

Vero is constantly refining WorkNC software in order to make milling work even more efficient. For instance, the current release includes a new high-feed strategy that was suggested by the tool-makers at Audi and developed in partnership with them.

While high-speed cutting (HSC) primarily involves creating high-quality surfaces, high-feed cutting (HFC) has been developed to achieve short processing times for roughing and pre-finishing operations.

Various suppliers have developed special tools with high-feed geometries for this purpose, with cutting edges that have a much larger line of contact with the workpiece than conventional round inserts.

This approach to machining reduces the radial cutting force on the machine and its spindle and allows significant increases in metal removal to be achieved.

Before Vero’s latest WorkNC development, most CAM users found they were unable to take advantage of high-feed tools, as the programming software could not readily reproduce the necessary high-feed tool-paths/geometries, resulting in an undefined allowance on the component surface.

This, in turn, impaired processing reliability in the downstream finishing process, but WorkNC’s high-feed strategy now prevents undefined allowances from appearing on the workpiece.

Mr Brunner and his colleagues were not only the driving force behind this development, they also provided the machine capacity required for testing purposes, which included cutting the negative surface offset of a press tool for a car door.

Whereas pre-finishing work for the outer door panel used to take 3hr 15min — and necessitated the cutting inserts being changed three times — processing with the new WorkNC high-feed strategy took 1hr 42min, without any insert change (the tool used was a 1DP1E high-feed mill with a 65mm ‘projection’ length from Ingersoll Cutting Tools).

“By using WorkNC’s high-feed strategy and the tools to match, we have reduced processing time in pre-finishing work by up to 30%; and because the main machining forces are in the Z direction — into the spindle — vibrations are reduced, and the tool generally runs more quietly, which has a positive effect on the cutting process.

“The new WorkNC strategy can also be used with negative surface offsets, which I believe is not currently offered by other CAM suppliers. In the future, we will definitely be using the high-feed strategy with all components in the pre-finishing processing step.

“We also appreciate the flexibility of the overall system. For instance, WorkNC’s post-processors are not encrypted; they can be adjusted by the user at any time.

“This has allowed us to significantly increase the level of automation in our single-part production over the past few years — and quickly adjust the CAM output to maximise the capabilities of increasingly complex machine technology.”