Poetry in motion

Poetry in motion

It’s Goethe and Schiller wherever you turn. But there are other names in and around Weimar that deserve recognition for their achievements. DMF Werkzeug­bau, for instance, that has made a name for itself in mouldmaking. One of the company’s machining fortes is wire EDM.

Mould insert with wire-cut ejector holes, oblique slides and the associated oblique penetrations

Lorenz Luczynski, one of the two managers of DMF Werkzeugbau GmbH in Nohra, Thuringia, puts some components on the table and gives us a glimpse of the product spectrum. “On a surface area of 1,300 square metres, we fabricate technically sophisticated injection and die casting moulds for items made of plastic, aluminium, zinc and magnesium.”

Most of the moulds made by DMF Werkzeugbau are one-offs. On the wire EDM machines, the company pro­cesses mould inserts and cores, cutting blades, punching dies and slides. The material employed is tool steel, some of it high-temperature. With wire diameters of 0.25 and 0.3 millimetres, they achieve a surface finish of 0.2 to 0.4 µm Ra. On small components, the company achieves parallelism and precision to within as little as five micrometres. As to the maximum workpiece size, the company quotes 700 x 300 millimetres for mould inserts, 250 x 200 millimetres for other parts and heights of up to 400 millimetres. Machining can take anything from 2 to 100 hours, depending on the workpiece.

Cutting angle up to 30 degrees

Because an increasing number of angled cuts arise during wire cutting, the Thuringian company benefits from the fact that the wire EDM machines from Mitsubishi Electric cut very precise angles. Luczynski lifts up such a part. “The smaller the workpiece, the bigger the angle that we can achieve. We manage up to 30 degrees.”

DMF Werkzeugbau GmbH in Nohra, Thuringia, has made a name for itself in mouldmaking.

The only conceivable alternative for Luczynski is die sinking. And only when the customer does not insist on absolute accuracy. Wire cutting, he says, is also much more economic than the old conventional process of die sinking followed by milling. And the whole pro­cess takes place today on a single machine that operates with a lower failure rate in addition. The only real scope for mistakes today, he continues, is with programming. During the tour, Luczynski explains what DMF Werkzeugbau is capable of in mouldmaking. “We can look back on about 15 years of experience in wire cutting. What’s more, we have all the equipment we need in-house and no longer have to contract any work out. This is appreciated by our clients. These are mainly producers of injection mouldings and plastics destined for automotive component suppliers.” The company certified to ISO 9001:2008 offers the full range of solutions – from item optimisation and the finished mould to a supply of sample plastics parts. In addition, DMF Werkzeugbau is also capable of supplying prototype moulds and, for the die casting sector, package solutions inclusive of deburring tools at short notice. The company has strengthened its competitive position by introducing efficient CAD-CAM systems early on and constantly updating them and training its staff accordingly.

On the wire cutting machine, DMF Werkzeugbau processes mould inserts and cores, cutting blades, punching dies and slides.

DMF Werkzeugbau can look back on about 15 years’ experience in wire cutting and has the full complement of equipment on its own site.

Expert advice and service

From an elevated position in the production shop, Luczynski views the three wire cutting machines from Mitsubishi Electric arranged in a neat row. “We’ve invested in an FA30-S Advance, an FA10-S Advance and an FA20-V. We chose the first machine on the strength of tests and the impressive price/performance ratio. As a satisfied customer, we then stayed with Mitsubishi Electric. The manufacturer’s expert advice and services also contributed to this. We were given really quick assistance with any problems that arose, so we didn’t see any reason to look elsewhere on the market. In addition, by resorting to a single supplier, we only have to stock parts for a single make.”

DMF Werkzeugbau has wire-cut the ejector holes, oblique slides and the associated oblique penetrations on this mould half.

On this mould half, the ejector holes, core seats and cores have been wire-cut.

The CAD drawing shows a component on which DMF Werkzeugbau has wire-cut the insert and cores.

The FA20-V went into operation in 2005, the FA10-S Advance in 2009 and the FA30-S Advance in 2013. The company also opted for the FA30-S Advance because of its larger working range. It is equipped with a high-speed generator, while the FA10-S Advance has an optional digital fine-finishing generator. The machines are adapted to the needs of DMF Werkzeugbau and are synonymous with high availability. The company ensures the continuous readiness of the wire EDM machines under a ­maintenance contract with Mitsubishi Electric. The contract includes annual maintenance by the manufacturer’s service staff, so Luczynski expects the machines to have a long service life and achieve a consistently high quality of machining. The operators themselves play their part by cleaning the threading and guide area and taking the opportunity to replace wearing parts.

Last year alone, the three wire cutting machines of DMF Werkzeugbau clocked up 12,000 hours of operation.

Deburring tool on which the external contour and large hole have been cut

Inserts for an injection mould on which DMF Werkzeugbau has cut the square core penetrations on the circumference

“As a satisfied customer, we then stayed with ­Mitsubishi Electric.”

No alternative to automatic wire threading

Matthias Dohne, wire cutter at DMF Werkzeugbau, threads a new wire on the FA30-S Advance. In doing so, he benefits from the user-friendly automatic wire threader that the FA10-S Advance is also equipped with. “Rapid and reliable threading are absolutely essential for us, as we usually work at night and at weekends, in which case the machine is unmanned. Last year alone, our three wire EDM machines clocked up 12,000 hours of operation.” Because of the night and weekend assignments, the company has invested in further optional extras – firstly, in a 20 kilo wire station that is indispensable for longer unmanned operation, and, secondly, in the Telecontrol and Teleservice tools. With the aid of Telecontrol, the EDM systems are monitored via a data line in real time.

The Teleservice tool permits remote diagnosis and online assistance from the Mitsubishi Electric after-sales service which is thus able to remedy hitches online. Luczynski opens up his iPad. “The machines are also continuously connected to the Internet. This means that, on their iPads and PC monitors, the staff concerned can view the same machine data and messages as are displayed on the screens of the operator terminals.”

Good work

Finally, to return to the reference to German poets: DMF Werkzeugbau GmbH demonstrates day after day that in Nohra, only about eight kilometres from the centre of Weimar, the town of Goethe and Schiller, that one’s livelihood does not necessarily have to depend on tourism and the commemoration of Germany’s greatest men of letters. Anyone who does good work will make a name for himself – among readers or customers.

Interview