Two generations at work
Sheet metal processing has been one of the core competencies of the WMF Group for decades. When it comes to bending complex components for coffee machines, the Geislingen-based company puts its faith in an experienced veteran and a nifty newcomer, both from TRUMPF.
Would you like one or two coffee grinders? A water tank or fixed water connection? And with or without the optional chocolate dispenser? When you buy a professional coffee machine, there are almost as many options to choose from as when you buy a new car. The WMF Group produces eight different basic models of its professional fully automatic coffee machines under its well-known WMF brand in the German town of Geislingen an der Steige — and the number of variants and optional extras is almost endless. Most of the machine is made from stainless steel, comprising some 50 to 100 different sheet metal parts, depending on the exact model. Some of these parts are highly complex. “For example, one of the sheets for the inner housing has 38 bends,” says Volker Simon, who heads up the coffee machine production. Sourcing those kinds of complex parts with the required standards of quality at acceptable prices is a challenge, which is why WMF prefers to rely on its own know-how, bending the majority of the parts in-house.
Green instead of blue
The manufacturer processes around 1,000 tons of stainless steel a year. The machines it uses stem from different decades: a TRUMABEND V 130 has been up and running for the past 12 years, and a few months ago it was joined by a TruBend Cell 7000. These are supported by 2D laser cutting machines and punching systems, once again made by TRUMPF. Blue doesn’t dominate, however. With the exception of the bending cell, all the machines in this uncluttered production hall are painted bright green, while the automation components are painted yellow. The TRUMABEND V 130 in the sheet metal processing plant stands out not only because of its color, but also the way it works. In collaboration with TRUMPF, the WMF Group automated the manual press brake using a robot from Motoman. The configuration may seem old-fashioned these days, but the machine has been running flawlessly for 12 years — seven days a week in three-shift operation — without requiring any downtime for repairs.
Just press the button
Before a new program can be set up on the machine, a lot of thought always goes into how to process and define the bend order: “How should the robot grasp the workpiece? How can we be sure the previous bends won’t get in the way? And where is a risk of collision? All these questions have to be tackled in advance,” says Hans Wagner, who is in charge of sheet metal processing. A teach-in procedure is then used to enable the robot to learn the individual steps.
The fact that the bending cell can switch tools and grippers fully automatically means that it can operate unsupervised 70 percent of the time.
“That sometimes means shutting down the plant for two days,” says Wagner. For orders of 50 pieces or more, WMF uses an automatic press brake instead of a manual one. This approach makes sense because the metal manufacturer gets plenty of repeat orders. “Once I’ve created the program, any repeat order in the future just requires me to prepare the material and press the button,” says Simon.
Watch the Innovative high-speed bending cell TruBend Cell 7000 at work:
Quick and accurate
The TRUMPF TruBend Cell 7000 bending cell, which was incorporated in the production facility in March 2015, offers a much more flexible approach. “As well as the housing and the chassis, which are both made from stainless steel, professional coffee machines also have lots of small sheet metal parts inside them. This system does a great job of bending angles and brackets very quickly and accurately,” says Simon, explaining why they chose the machine. Just like the TRUMABEND V 130, the TruBend Cell 7000 can handle sheet thicknesses from 0.8 to 2.0 millimeters. The fact that the bending cell can switch tools and grippers fully automatically means that it can operate unsupervised 70 percent of the time. The machine works so quickly that the offline programmers are never short of things to do. Over the past three months they have defined the processes for 150 different parts, and they’regradually adding more.
No supervision required
“In the past, our production workers had to be bending specialists to set up and operate a machine,” says Wagner. But that’s no longer necessary with the TruBend Cell 7000. Once the program has been properly set up, it runs smoothly without any supervision. “The key here is to have computer-savvy employees doing the programming,” says Wagner. In the future, new additions to the WMF Group’s production team will explicitly be required to have computer skills. But when it comes to assembly and testing, there’s still plenty of manual work to do. A mechanic assembles the different parts of each coffee machine manually, installing the water tank, bean hopper and display and carefully connecting up the myriad cables. A different colleague then carries out a thorough inspection of each coffee machine. The WMF Group has been producing professional commercial coffee machines in Geislingen since 1927. “German-made quality is one of the key factors behind the WMF brand that sets us apart from our competitors,” says Simon. “We’re one of the world’s leading manufacturers of professional coffee machines — and that’s the way we want it to stay!”
Contact us: MastersofSheetMetal@trumpf.com
This article was first published in spring 2016.