Gearing up with robots
if you want to avoid mistakes, let robots do the work: that’s the philosophy of german gear-manufacturer stelter Zahnradfabrik. Now the company’s operations have become even more efficient, with help from Seco.
The administrative building for gear manufacturer Stelter in the north German town of Bassum may look old-fashioned, but it’s home to a business that’s at the cutting edge of its field. The company’s Production Director, Christian Stelter, explains,
“We have an exceptional level of automation, with several robots linked together in a single process.” This highly automated arrangement allows for a dull, grey blank to be put on a conveyor belt and emerge shining at the other end, following a whole series of turning, milling, and grinding procedures. The company likes to say that its products are “made by magic hands”, a reference to the work of its industrial robots.
Combination of operator and machine
Stelter Zahnradfabrik’s newest production hall, built in 2014, features a number of machines that make the various gears required for a new duplex clutch gearbox for a major German automaker. At each workplace, a computer screen reminds operators to carry out various checks at predetermined intervals. Is the inner diameter still within tolerances? How deep is this or that groove? Every few minutes, the screen ashes up a new parameter for checking. “We decide what needs to be checked, and we can see in the office if the checks have been done and what values they show,” explains Stelter.
This combination of operator and machine is one that Stelter and company Technical Director Karl-Heinz Wilkens believe will characterize the industry for some time to come. “A human being is always in charge,” says Wilkens. “A person controls the control processes and programs the programs. But people should be mostly involved with quality issues. Filling the oil tank can only be a sideline.”
Stelter says it’s a matter of getting rid of the human element as a source of errors. By using robotic equipment managed by workers, who in turn are helped by computer systems, he has put his staff in charge of quality. “We started using this system ten years ago, and we have improved quality enormously,” he says.
Quality is the key. According to Stelter, his company is one of the top three in the field, and he puts this down to quality, flexibility and, of course, price. And that means absolute reliability in the 24-hour-a-day production process. As Wilkens puts it, “We have an automatic line, so we need insert operating life times that are reliable. If we have to break the process, we lose production. And that’s where Seco Tools has helped.”
Wilkins explains that inserts featuring Seco’s new Duratomic grades have improved insert operating-times by 20 percent, leading to a five percent improvement in productivity. “We’ve won time, and the process is faster and more stable,” he says. Stelter adds, “It helps the workers, too, if they don’t have to interrupt the process so often.”
Seco and Stelter working as a team
Stelter sees the relationship with Seco as a two-way process: “We go to them with problems, and they come to us with ideas,” he says. Seco Tools’ Regional Sales Manager for North Germany, Karl Förster, has been the link to Stelter for the last 20 years. “It’s a team,” he says. “We all know each other well, and we’re all passionate about productivity.” Demands on quality and reliability have increased enormously over the last few years, and the product has changed too. And, as customers’ demands increase, Stelter demands more of his suppliers.
Seco and Stelter are currently working on optimizing the turning of HRC 60 hardened materials to improve reliability and productivity by using the new CH grades in the Secomax CBN family which feature a new substrate. They’re also testing the new TGH1050 grade – Seco’s MDT system for recess turning – again to further improve reliability and tool costs.
Stelter doesn’t think that technical progress can be as fast in the future as it has been, but demands will continue to rise, especially in terms of transparency. He sees a time when customers monitor the machines directly and watch the process as it happens.
By Michael Lawton
Photos by Thomas Müller
Illustration by Martin Nicolausson/Agent Molly & co
Improved operating times
Seco Tools’ new Duratomic grades, TP0501, TP1501, and TP2501 have signifcantly improved insert operating- times at Stelter. The grades have been created following analysis of surface and substrate at the atomic level. Seco’s wiper geometry also ensures excellent surface quality at high throughput.
A welcome side-effect is that the chrome-colored inserts turn black when used, ensuring that inserts with unused cutting surfaces are not discarded.
Stelter Zahnradfabrik has seen rapid growth over the last few years. Turnover has risen from EUR 40 million to EUR 65 million since 2012, and staff numbers have increased from 210 to 350. The company specializes in making and finishing all kinds of gears. Automotive makes up 60 percent of production, other industry 35 percent, and large gears for such fields as wind power and railways, 5 percent.
Fixed gear for duplex clutch
Material: 20 MoCr 4
Operation: outer face and side turning
Machining objective: increased insert tool life
Machine tool: Emag VL 5i with Seco Tools’ CNMG120408W-TP2501 insert
Machining data: 700 units were turned, compared to 450 previously