Wire EDM opens the door to high precision

Wire EDM opens the door to high precision

In the hundred years plus of its company history, DORMA – today a group with a 6,500-strong workforce – has evolved into a globally operating systems supplier of door-related products. The world market leader in door control, movable room dividing systems and glass fittings has 71 subsidiaries in 47 countries and operates three plants at its headquarters in Ennepetal, where 1200 people are employed. The company’s own tooling department demonstrates the high manufacturing depth at DORMA. A wire erosion machine from Mitsubishi Electric underlines the commitment to quality.

Every day, we open and close doors as a matter of course without giving any thought to the assistance we’re given by modern door closer systems or totally automatic door systems. These unassuming technical helpers are the bread-and-butter of the DORMA Group. Since its founding in 1908, the company has produced 100 million door closers, and at the Ennepetal site alone this has been 10 million sliding door closers since 1986. Today its products can be found all over the world, including in such prestigious construction proj­ects as the Burj Khalifa, where DORMA has contributed 13,000 door functions to the world’s tallest building.

In Ennepetal, DORMA GmbH & Co. KG, the biggest subsidiary of the DORMA Group, operates three plants focusing on the sectors of door control,automatic door systems and security systems.
Door control, an activity that DORMA has been developing since the Nineteen Sixties, accounts for the biggest chunk of sales. What has happened since then is described by Christof Zuschlag, manager of the door control plant, citing an example: “Modern door closers hardly require any effort during the opening of a door today. This means that even young or infirm people can use doors effortlessly and almost without having to overcome any resistance.”

A quality commitment across the board

In production DORMA goes for high manufacturing depth. “This permits better quality control and gives us greater flexibility,” says Zuschlag explaining this philosophy. His field of responsibility comprises, among other things, toolmaking, and it is not only the plants in Ennepetal that benefit from it. The plant manager describes the procedure: “We produce here dies, for instance, for stamping parts in the adjacent pressing shop. Many of these parts are destined for further processing at our foreign subsidiaries.” The high quality standard pursued by DORMA GmbH & Co. KG in all respects is a continuous theme throughout the production chain. Absolute precision in production also applies in the tooling department. Since conventional machining methods would reach their limits in terms of accuracy sooner or later, DORMA has added wire EDM to its spectrum of technologies employed. “This is the only way of achieving the accuracy that we need in the downstream work processes,” says Christof Zuschlag commenting on the importance of wire erosion. The most recent purchase in this area, an FA20-S Advance from Mitsubishi Electric, is a replacement for an old, defective wire EDM machine.

Innovative technology sets new standards

The comparison of quotations on paper and outstanding results from the first cutting trials in spring 2010 soon singled out the machine from the Japanese manufacturer. “Just as impressive were the competent sales staff and excellent organization that went into processing the quotation and the purchase order,” Christof Zuschlag adds. The machine was very soon installed and integrated in everyday production.

The plant manager then continues: “We very soon realized that we had found a strong partner in the shape of Mitsubishi Electric.” Training in good time by the manufacturer, prepared our programmers and operators to the point that they could get straight down to work.

In practice, the FA20-S Advance soon showed that it was capable of fulfilling its promise. “The changeover to programming and control software that was new to DORMA didn’t pose any problems,” as Matthias Schwieder, in charge of programming in the door control division, recalls. Hans-Walter Herth, head of tooling, adds: “For us, the advanced technology and high-per-formance generator also mean twice the cutting speed and maximum flexibility.”

The new wire erosion machine has also improved machining accuracy appreciably. All the materials employed – steel, aluminium and other conductive materials – are cut not only faster by the FA20-S Advance, but also with extreme precision. The wire diameter of 0.1 to 0.25 mm permits the finest cuts even during the first machining step. “In cases where several recuts used to be necessary, a maximum of three cutting operations are sufficient today,” says Christof Zuschlag explaining the difference – an improvement that also saves time and permits more flexible working methods.

Ready for expanding capacity

Flexibility in production at DORMA is an altogether decisive feature. The Mitsubishi Electric wire EDM machine not only supports toolmaking activities, but is responsible also for the machining of other production equipment and custom parts. The multifaceted range of parts therefore comprises not only tool components, but also special clamps and high-precision gauges for quality assurance. “Thanks to the machine’s high performance, we are able to produce the necessary parts at short notice,” Christof Zuschlag explains. The FA20-S Advance is now working to high capacity: “If required, the machine runs in several shifts, which also means in unsupervised operation at the weekend.” Increases in incoming orders can thus be handled without difficulty.

The capacity situation of the FA20-S Advance is just one indication of an up-turn in business at DORMA. Having come through the turbulence of last year in good shape, the company is now ready to look ahead with optimism.

“In the coming years we shall continue to build on our business sectors – this applies just as much to stable segments like door control as to service activities like installation and maintenance,” says Christof Zuschlag. And everything will continue to be pervaded by the striving for quality and innovation. The plant manager concludes: “Because this is the only way of further-improving the ease of opening and closing doors.”

Interview