At three locations in Europe, the USA and Asia, the HÄRTER Group produces stamping tools, injection moulds, stamped, deep-drawn and plastic parts, and integrated components for electronics and automotive. With high vertical integration – even in toolmaking – the specialists ensure maximum flexibility and quality. Needless to say, wire-cutting is also part and parcel of this.
Expert supplier to the electronics and automotive industries
“We always find a solution,” says Rüdiger Gruner, head of EDM, assessing the performance of toolmaking at the headquarters of HÄRTER Werkzeugbau GmbH in Königsbach on the outskirts of the northern Black Forest. In 1964 Wolfgang Härter founded the company owned and run today by Martin Härter in the second generation. The turn of the century saw the onset of a rapid shift from a regionally oriented toolmaker to a globalised supplier to industrial and automotive customers. A stamping shop was first integrated, followed shortly afterwards by the establishment of the first business connections all over the world. From then on, HÄRTER also started assembling components. As of 2012, the company extended its production to include metal-plastic composite parts. With currently five production sites on three continents and 1450 employees, HÄRTER now ranks among the global players, providing expert service to the electronics and automotive industries in particular. The product portfolio includes stamping tools, injection moulds, stamped and drawn parts, parts made of a mix of metals and plastics, as well as ready-to-install components. HÄRTER sees itself as a development and production partner to the electronics and automotive industries. Right at the design stage for electrical and electronic assemblies, HÄRTER’s experts contribute their expertise in close cooperation with customers. This applies firstly to the design and the choice of materials, while also extending to the company’s production and assembly options, as well as to the logistics chain to enable the punctual supply of parts and components. It goes without saying that, as a partner of the automotive and electronics industry, HÄRTER is certified to ISO 9001, ISO 14001 and ISO TS 16949.
For the head of EDM Rüdiger Gruner, the high quality of the tools designed and manufactured in-house has a large hand in the success of the company. More than 250 stamping tools, deep-drawing dies and injection moulds are produced annually. “Thanks to our high vertical integration, we have comprehensive knowledge of all the associated production steps,” explains Gruner. In addition to milling and turning, this includes wire-cutting. Wire EDM is still indispensable in toolmaking, Gruner believes, regarding this process in fact as a key core competence for toolmaking. In his estimation, the only way to profitably machine a variety of geometries to the required accuracies is with EDM.
EDM as a decisive core competence for toolmaking
This is why HÄRTER has more than 23 wire-cutting machines at its parent plant in Königsbach, including an MV2400R from Mitsubishi Electric since April 2014. The parts are programmed at several workstations of a central CAD/CAM system.
The specialists in the workshop call up the NC programs from a data network. Working as a team, they optimise order throughput and machining at the various wire EDM systems. Gruner has divided the entire EDM production area into the two categories, “standard” and “high precision”. In the standard category, punches, dies and tooling plates are cut with 0.25 mm diameter wire to a surface finish of as good as Ra 0.3 μm. This is where it is a matter of productivity and reliability. In the other category, the wire-cutting systems machine the parts with 0.2 mm to 0.03 mm diameter wire to the highest accuracy and surface quality with a finish of as fine as Ra 0.07 μm. “Although we’ve been very satisfied with the wire-cutting systems of a single manufacturer for many years, we’re occasionally on the lookout for a complementary system. In our research, we were drawn to Mitsubishi Electric, which is why we invested in an MV2400R as an alternative to the previous machines in 2014,” Gruner reports.
High flexibility for carrying out orders at short notice
Mitsubishi Electric provided powerful arguments in favour of this investment. The MV2400R comes with a large working range. It also features highly reliable wire threading. “During standard machining particularly, where we machine tooling plates and small series of punches and dies, a large work space facilitates higher productivity. However, we can only exploit this profitably if the wire-cutting machine reliably operates unmanned for many hours,” explains Gruner. After more than two years in toolmaking in Königsbach, the MV2400R has proven that it totally satisfies these requirements. Gruner adds that he is also impressed by the MV2400R’s repeatability. For example, up to 80 mm high punches have to be cut. In doing so, the wire-cut EDM system from Mitsubishi Electric ensures +/- 2 μm contour accuracy. Depending on the programmed cutting speeds, it achieves a roughness of Ra 0.3 μm – a high surface quality made possible by the drive with Tubular Shaft Motors in combination with the Optical Drive System. “The MV2400R impressed us with its technical performance, so we’ve now found a serious alternative to the other wire-cutting machines,” says Gruner. He is delighted by the Intelligent AT wire threader. It works particularly reliably and, as Gruner confirms, even if the starting hole is not exactly positioned.
In addition, a drill hole only 0.1 mm larger than the wire diameter is sufficient. Working fully automatically, the machine detects the start hole and threads the wire reliably. “During preliminary machining particularly, we make sure the wire-cutting machines can operate without supervision. This entails ease of set-up and unmanned operation for many hours. The MV2400R meets these requirements,” Gruner reports. He also attaches special importance to the availability of wire-cutting machines. At the Königsbach-Stein location, the machines have to work productively for more than 70 per cent of total time. The MV2400R has been impressive with its long maintenance intervals, low consumption of filter media and good accessibility for maintenance and service – features that minimise downtime. The machine’s ergonomics also benefits availability. The work space is highly accessible, and the fixtures and workpieces can be loaded and unloaded quickly and comfortably at an ergonomically favourable height. These outstanding features, Gruner stresses, promote the machine’s acceptance among his employees, who prefer wire-cutting machines that can be operated and maintained easily and trouble-free. This way production runs smoothly without disturbances and interruptions. Gruner adds that the high reliability and unsupervised operation of the MV2400R are particularly useful for production of single parts and spares at shortnotice. “We can totally depend on Mitsubishi Electric’s wire-cut EDM to uphold the high degree of flexibility that is absolutely essential for orders executed at short notice,” he continues. The collision protection system in all axes he finds particularly useful. Should the wire guide collide with a workpiece or a fixture due to a clamping or programming error, the control system immediately interrupts travel motions to prevent damage to the machine. The MV2400R can therefore be safely used during the unmanned night shift. The employees can rely on the machine to fully cut the programmed and clamped workpieces overnight. For production stints of several hours, this reliability is supported by an additional wire station for 20 kg wire reels.
Thanks to the reliable automatic wire threader and the effective collision protection in the axis drives, the MV2400R reliably cuts all the geometries of the standard range with accuracy of a few μm during unsupervised shifts.
Previously, when investing in wire-cutting cutting technology, Gruner and his EDM specialists had almost exclusively insisted on obtaining the maximum in terms of equipment and functionality. As Gruner points out, this makes only limited sense in an increasingly competitive climate. “You don’t necessarily have to drive a Mercedes to get to work on time,” he says, outlining his current attitude towards upcoming investments. From now on, he intends to pay more attention to the right balance between cost and requirements in the given situation. In this aspect, he says, the procurement of the MV2400R was a first step in this direction. “All the geometries to be cut for standard jobs are handled by the MV2400R with the required accuracies. It is easy to set up and operate. It also runs with uncoated wire. With this, it is up to 30 per cent cheaper to operate than the other wire-cutting machines equipped with extremely high-end engineering. On the basis of our experience to date, the wire EDM system from Mitsubishi Electric with its profitability and reliability has proven to be a highly expedient alternative to the tried-and-tested machines of other manufacturers,” says Gruner summing up. An update to the software makes it possible to raise productivity and profitability still further. Now several workpieces in multiple clampings can be machined much more easily in a single process. This means the toolmakers at HÄRTER in Königsbach-Stein can fully reap the benefits of the exceptional dependability of the MV2400R during unsupervised night shifts.
Maximum reliability even in unmanned night shifts
At HÄRTER the focus is on the employee – so this is why health and well-being at the workplace is supported with a programme encompassing exercise, nutrition and knowledge. For example, employees are encouraged to leave their cars in the garage and actively exercise on the way to and from work and in their spare time – the 97 modern e-bikes from smart give HÄRTER’s employees and trainees plenty of incentive. With the futuristic technology of the e-bikes, HÄRTER not only improves the fitness of its workforce, but also does its bit for the environment as a side-effect.
On regular Health Days, the company turns its attention to nutrition, exercise and relaxation. Employees can thus find out what does them good and put together personal programmes of lectures and check-ups and actively participate in health drives. In addition to a supply of regionally grown apples, HÄRTER’s employees can also obtain on much-reduced terms membership of a partner fitness studio where they can improve their stamina on the treadmill or strengthen their back muscles in a gymnastics course.
Name and place of company:
Martin Härter and Alfred Pikl
Number of employees:
Toolmaking for stamping and deep-drawing tools, injection moulds, metal-plastic composite technology, series production of stamped and deep-drawn parts and injection mouldings, component assembly
HÄRTER Werkzeugbau GmbH
GmbH & Co. KGaA
75203 Königsbach-Stein, Germany
Tel +49 (0)7232 30460
Fax +49 (0)7232 4214
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Mitsubishi Electric Europe B.V.
D - 40882 Ratingen
Tel.: +49 (0)2102 / 486 - 6120
Tel.: +49 (0)2102 / 486 - 7600
Tel.: +49 (0)2102 / 486 - 7700
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