Immaculate steel moulds for perfect-fit closure systems

Immaculate steel moulds for perfect-fit closure systems

Immaculate steel dies and moulds for the production of high-grade die castings and injection mouldings call for machines that perform outstandingly. By purchasing an MV2400R wire-cutting machine from Mitsubishi Electric, Seehafer & Marohn are responding to the higher standards of precision, ­quality, punctuality, accurate fit, contour-trueness and flexibility expected by customers. They benefit from high productivity and lower piece costs combined with faster throughput and delivery.

Customers benefit from high productivity.

Seehafer & Marohn GmbH & Co. KG in the “locks & fittings” town of Velbert has been synonymous with precision die and mould making for over 50 years. It sees its challenge in satisfying customer demand for steel dies and moulds with an outstanding surface finish and high precision. For this, Seehafer & Marohn makes use of modern EDM technology. On a surface area of 1200 square metres, the company with its twelve employees makes precision steel casting dies and injection moulds for the production of technically sophisticated items. There are a lot of benefits to using these steel dies and moulds made of robust, high-alloy tool steel in mass production: low material loss, constant product quality in the long term and rapid production cycles. The die casting process produces items made of zinc or aluminium, for example, while injection moulding is used for plastics. The range of products also includes cylinders and lock systems resulting from the fact that the “key region of Velbert” has been home to companies of the locks & fittings industry for centuries. In addition, the maker of dies and moulds has also established itself with door handles and trim parts for the automotive industry. The orders mainly come from systems suppliers, most of which operate globally. And this means that steel dies and moulds from Seehafer & Marohn are even used in China. With the production of moulds for electrical housings, the company has extended its clientele into the electrical industry. For the production of high-quality prototypes, the company also machines sample dies and moulds.

Supplying replacement parts even after seven years.

“We’re not so big that administrative duties hamper our flexibility and innovation, but big enough to satisfy the needs of our customers at any time,” explains Dipl.-Wirt. Ing. (FH) Klaus Marohn, a graduate in engineering management. He and his brother Frank are the Managing Partners of Seehafer & Marohn in the second generation. The sectors they serve demand dies and moulds exhibiting high precision, parallelism, surface finish, exact contours and defined taper. The dies and moulds must also ensure high process security so that they contribute to a long service life in parts production. Deadline compliance and a quick response are also necessary and are important for repair jobs so that machine downtime in customer production processes can be kept to a minimum. Some customers also request the advance stocking of spare parts. As in one special instance, this makes it possible to supply spare parts that fit first time, even after seven years. Against this background, all-round service enjoys high priority, extending from initial ­consultations and production through to maintenance and servicing of the dies and moulds. To produce steel dies and moulds with the required characteristics, wire-cut EDM technology is essential. This exceptionally precise cutting method is ideal for the machining of the hardest steels, with the cut edges meeting the highest standards of accuracy in terms of shape and dimensions.

Significant reduction in operating costs.

An unscheduled but safe investment

“In October 2014 we were faced with the situation of having to extend our machine park at short notice. This new investment became necessary because an older machine from a different manufacturer had a serious malfunction and we were under pressure to complete our orders on time. The new machine is the MV2400R wire-cut EDM from Mitsubishi Electric. This marked a big step into the high-end bracket. The new machine has a whole range of interesting improvements and novelties,” Klaus Marohn reports. “We’re very open to innovation, but investing in an inappropriate machine could be problematical for a business of our size. We have always attached importance to new but proven technology that meets our needs at least into the ­medium term. All the same, this new investment was not exactly a step into the unknown as we had been using an FA20-S Advance wire EDM from Mitsubishi Electric since 2008. We had had very positive experience with this model in terms of quality, precision and reliability. Only rarely did we have to resort to the service hotline and we always got professional support.”

The investment helped to further streamline the machine park. A big advantage is that the operating strategy of the new machine is largely identical to that of the FA20-S. Before order placement, an employee of Seehafer & Marohn put a demonstration machine to exhaustive testing at Mitsubishi Electric in Ratingen. Intuitively, he was able to operate the machine without any difficulty, and this eliminated the need for any formal training. The new machine comes with a whole range of innovative technologies that offer scope for economies and, with a large diversity of functions, permit the machining of dies and moulds with increasingly complex geometries. In addition, the basic package includes virtually all extras, and the excellent price-performance ratio offers the prospect of rapid amortisation. The new machine was delivered on Friday, 24 October, set up and commissioned the next Monday by a Mitsubishi Electric fitter. The first work on the MV2400R was then carried out on the Tuesday.

Innovative features for comfort and efficiency

With its Natural User Interface (NUI), Mitsubishi Electric has again improved operating comfort over that of the predecessor model. Intuitive operation is very straightforward with the aid of input masks and symbols. Workpiece set-up is performed with the aid of logically structured 3D views on the machine’s 15″ touchscreen. The Easy Set Up instructions unite all the main settings on a single screen. Furthermore, through measurement of the workpiece surface with a dial indicator, the wire’s angle of inclination can be automatically compensated for and adapted to the precise workpiece length. “Malfunctions are displayed immediately in messages on the monitor. In an extra window, the operator is given a problem analysis and instructions for remedial action. In addition, for complicated applications, he can check all the machining steps in 3D on the monitor,” says Lothar Dördelmann, in charge of production at Seehafer & Marohn. “The working range of the MV2400R enables us to machine workpieces from the size of a matchstick to dimensions of 1050 x 820 x 305 mm with a maximum weight of 1500 kg.”

“On the new machine, we’ve found that machining speed is up to 30 per cent higher for standard applications. This is of great importance for us – not only for the handling of run-of-the-mill jobs, but particularly for the rapid processing of urgent jobs and in cases of repairs,” says Klaus Marohn. “The new Tubular Shaft Motor drive concept goes a long way towards improving workpiece quality.” This is an ideal solution for adapted and totally cogging-free motions of the axes by means of magnet motors. Motions and positioning can be sensitively controlled. This results among other things in precise wire guidance with clean cuts, even on challenging tapers.

Dependable automatic wire threader

“We’re delighted with the new automatic Intelligent AT wire threader. This technology has had a lasting effect on working efficiency, whether we use 0.2 or 0.25 mm wire. After wire breakage, be it submerged in the tank, in the kerf or after interruptions in start-hole drilling, wire threading is performed reliably, swiftly and with great precision. We used to have to guide the wire back to the insertion point and thread it all the way through again,” Dördelmann explains. “So we’ve gone over to setting up workpieces in the afternoon or evening that can be machined on the MV2400R overnight. The machine will run without supervision, so we save a lot of time, use less wire and boost productivity noticeably.” So that they’re always aware of the state of progress at night, at weekends and on public holidays, Seehafer & Marohn have optionally invested in the mcAnywhere Contact function. The EDM automatically relays status messages in the form of standardised text messages to various freely definable mobile phone numbers.

If a workpiece doesn’t take all night to machine, energy is saved until work is resumed. Because, thanks to the new generator technology, when the workpiece is finished, the machine shuts down all stand-by ­systems into sleep mode. The activation of this mode results in a dramatic reduction in energy consumption and supplements the already generally achievable energy savings possible as a result of the innovative strategy of the MV Series from Mitsubishi Electric. Also worth mentioning in this connection are the savings of cutting wire, deionising resin and filter cartridges over the FA20-S Advance. The same quantity of eroded material is achieved with a significant reduction in operating costs, which has a beneficial effect on resources and the environment.

“If we’re to give our provisional verdict, we can say that we’re very happy with the quality, precision and machining time in the machining of steel dies and moulds for the production of our customers’ intricate die castings and injection mouldings. The positive feedback from our customers confirms our assessment. Thanks to the outstanding performance of the wire-cutting machine, its huge range of functions and flexibility in use, we achieve considerable savings. With a marked ­reduction in operating costs, improved competitiveness and its outstanding price-performance ratio, we expect the machine to pay for itself in a relatively short time,” says Klaus Marohn summing up. “We are certain that the dies and moulds for the automotive and electrical industries will continue to become more complex and geometrically intricate. And the production technology and capacity of the innovative MV2400R put us in an excellent position to deal with this.”

Interview