At P&M Werkzeugbau, Tebis enables automatic programming at the click of a button

P&M Werkzeugbau in Marienfeld near Harsewinkel, Germany was founded in 1998 and manufactures mostly series dies, pilot series and prototype dies for sheet metal forming for the automotive industry and its suppliers. Their products also include highly complex drawing dies, transfer dies and progressive dies for both technical parts and outer skin parts. These average 25 to 30 t – in the medium size range for dies in the automotive industry.

The expert’s die manufacturing portfolio also includes contract milling, pressing prototypes and pilot and small series on the full production presses in the company's technical center. Despite having a well-defined focus, the company has also positioned itself as highly diversified and viable for the future.

The large components of a die aren’t usually the parts that require the most effort in programming or machining. "Their number and scope in a transfer die, for example, is ultimately manageable,” explains Martin Zetzloff, head of design and programming at P&M Werkzeugbau. "Instead, the challenge lies in the smaller workpieces in sizes up to 500 mm – in the large number of trim and coining steels and sliders that are included in a die.”

Bringing their experience from many automation and digitalization projects, the Tebis experts worked with Zetzloff's team to sketch out the future processes and structures. "The calculations revealed that we could manage with a single high-performance 5-axis machining center,” the design manager explains. "However, this requires a high degree of automation – both on the machine and in programming.”

The company has extensive NC programming experience dating back several decades. "We’ve already tested and used many different systems," Zetzloff recalls. "But with each system, we experienced the same issue: Though we usually had a very good handle on the large components, the true challenge came from the many small parts.”

The die manufacturers encountered essentially the same problem with each programming system. Where one offered smart 3D strategies, it couldn't drill a single hole. On the other end of the spectrum are "semi-intelligent" 2D programming systems that balk at 3D milling.  "We very quickly reached the limits of all the systems we’d tried," Zetzloff recalls. "The program packages limited our options for modification and were very restricted. We often wished for different features or even different approaches than the systems could offer."

Tebis is a very open system. "Which offers so many possibilities for users", Zetzloff affirms. "To put it plainly: Tebis is clearly our best choice as an overall package for sheet metal forming." For example, the interfaces offers to Soflex and to the CAD workstations.

To ensure that everything works as planned for those responsible at P&M Werkzeugbau, they first joined forces with the experts at Tebis to specify the details of the underlying structures and strategies. "We told Tebis how we wanted to work in small part manufacturing in the future," Zetzloff recalls. "We explained in detail how we want to be able to machine in the first and second setups and what unattended operation means for us. We told Tebis how we want to mill in the future. And the Tebis experts showed how to accomplish those objectives."

The effort that the die manufacturer and the software provider invested in shaping this precise definition of future machining is paying for itself. The system now does exactly what the die manufacturers had hoped for.

Experts from Tebis came to Marienfeld and adapted the system to precisely meet the users' needs and to the range of parts to be machined in order to ensure that the software includes all of the features expected of it by the die manufacturers. They took into account the established conditions in the company and the tools already in use as well as future development opportunities.

But: "The Tebis platform is essentially empty when it’s set up. It needs to be filled with life by the user," Zetzloff says. "The most important key is the user expertise that flows into the system in the form of libraries. And this is the key to successful NC automation – the libraries containing the data that Tebis needs for programming: The more detailed and comprehensive information in these libraries, the better the automated programming will work.”

Two employees worked at P&M Werkzeugbau for two years to establish the extensive libraries. For example, for each existing cutting tool, they contain all possible application types, exact geometries and optimal cutting data with a high degree of detail.

Zetzloff is more than a little proud of these libraries: "Only the auto manufacturers themselves are likely to have more comprehensive and higher-quality libraries," he’s certain. "The effort that we’ve invested and continue to invest in ongoing maintenance is paying off. Because the more expertise a programming system contains on the categories of a cutting tool, for example, the better it can generate automated programs that also run optimally.”

The die manufacturers have therefore ensured that the overall geometry of the tool and holder can be correctly generated from the libraries by independently measuring and drawing all of the records. Accurate data is recorded for the clamping devices that the die manufacturers fabricate themselves (roughly 90 percent) and for the remaining clamping devices they’ve purchased: The die manufacturers have precisely measured them themselves.

The die manufacturers obtained the geometry data for their two Hermle C42Us in the "virtual machine" provided by the machine manufacturer. "However, we also had a team of experts from Tebis on site with us. The team precisely measured the machine and then implemented it in data synchronization," says Zetzloff. "This is the only way we can be certain that we’re working with the right values and settings – and that everything we simulate in advance can then run on the machine as precisely as it was calculated.”

The virtual world represents all the relevant parameters from the small part manufacturing at P&M Werkzeugbau with 100 percent precision. "This is the only way can we ensure that everything we program is also implemented one-to-one on the machine," Zetzloff stresses. "Our approach to generating programs is on the conservative side. But it’s very safe from a process standpoint. If all collision checks in the virtual world using the data from the machine, tool, clamping devices and workpiece are accurate, then the machine will run safely with no collisions.”

And this applies to all areas: From the first chip to roughing, finishing and fine finishing, all workpieces are processed unattended. The employees set up the workpieces and place them in workpiece storage in the cell. The system then decides when and on which machine the parts will be processed based on their priority. The employees on the machine can now concentrate on what's important, significantly reducing the probability of errors.

The work has become much less stressful for the machine operators. The critical decisions have already been made in advance and have been incorporated in the programs based on the rules and libraries. And all the essential data is clearly recorded in the system: for example, when a tool needs to be changed.