Flexibility conquered the market

Modern crankshaft production takes place on machining centers of the Starrag Group

With delivery periods of weeks rather than months, the crankshaft manufacturer Feuer powertrain succeeds in conquering the European market in less than ten years and advancing into the group of world leaders. The key to success: The consequent departure from the previously standard production of crankshafts on special machines. Instead, the production lines consist of machining centers - such as the horizontal HEC 630 D from Heckert, a subsidiary of the Starrag Group - which make production fast, flexible, high quality and ultimately profitable.

Crankshaft production is considered as the supreme discipline in metalworking. Hardly surprising, since this key component of an internal combustion engine requires 20 to 50 machining processes until it is ready for use - depending on the size and demands of the respective motor. Feuer powertrain produces cast iron and forged crankshafts 300 – 1,400 mm in length in small and large series for conventional car engines from VW, BMW, Audi, Ferrari, Jaguar, Maserati, GM and others, but also for the high-end 12-cylinders of Bentley or Rolls-Royce. They are highly sought after, not just in the automotive industry, but also in trucks, industrial engines, ships and generators.

The approximately 650 employees at the company's HQ in Nordhausen, Thuringia, produce up to 1.5 million crankshafts per year and supply customers all over the world. Further growth will come from the new plant in Tunica, Mississippi, USA, which is commencing production this year to supply the American market. A manufacturing plant in Asia is to follow and, in Nordhausen too, further construction is planned.

And so the success story continues. Which is not too surprising, since company founder and namesake Dieter Feuer, his partner Bernd Gulden and CEO Oliver Wönnmann founded the company in 2003 to revolutionize crankshaft production with their new company "Feuer powertrain". Their goal was to conquer the market with high flexibility and speed, and to be the market leader in Europe no later than 2010 - a goal they have achieved. Feuer powertrain, with a turnover of roughly 150 million euros annually, is now among the four leading vendors worldwide.

Machining centers replace special machines

Feuer powertrain really did succeed in completely redesigning the production of crankshafts. Because for many years, special equipment was used exclusively to perform the wide range of operations require to produce a crankshaft. They include cutting to length, centering, turning, milling and turn broaching, deep hole drilling, compaction rolling and straightening with rollers, rolling, dual-head orbital grinding, precision balancing, polishing and heat treatments. A variety of measuring and testing procedures have to be conducted before the finished product is ready for delivery.

Special machines are expensive to buy and inflexible in processing, making their use only worthwhile in large-scale production. The unit costs for small and medium-sized series can be prohibitively high. Which is why those responsible at Feuer powertrain looked for - and found - alternatives: Every production line in the plants, no less than five at present, at the company's Nordhausen headquarters consists entirely of interlinked Heckert machining centers. They differ only in their complexity and the number of stations, because some tuning tasks are only required in the high-end class. The degree of automation also varies. While the employees certainly intervene manually in lines for small series of 1,000 or 10,000 at one point or another, production in plant 2, for example, is fully automated. The usual batch sizes there are in the order of 10,000 to 100,000 units.

One feature all the production lines have in common is that they can be retooled quickly and with little effort. This enables the qualified personnel to react extremely quickly and flexibly to new orders. This is an important success factor, as Hubert Singer, CTO emphasizes: "Where others require an average of six to eight months, we can deliver in just eight weeks. With our manufacturing concept based on machining centers, we master the balancing act between productivity and product diversity."

Standard machines and in-house processes

Over 300 machine tools are in continuous operation in Nordhausen, 24 hours a day, seven days a week. 42 of them come from Heckert, which is part of the Starrag Group, a global technology leader in precision machine tools. They have been working together since 2007. Fikret Ersindigil, Head of Process Optimization, recalls: "That's when we began switching production to processing centers. For a rush order we urgently needed three machines for drilling and milling, and Heckert was able to supply us with them immediately." The machines in question were CWK 500 D horizontal centers, which Feuer powertrain integrated into a semi-automated stand-alone solution for the urgent small series. "We were able to fulfill this order and gain experience with Heckert machines at the same time", Fikret Ersindigil explains. After all, he and his colleagues were still on the lookout for suitable equipment suppliers for their new concept. "An early attempt to transfer the establishment of a production line to a machine tool manufacturer as a turnkey project didn't meet our expectations", reports the process specialist. "So for the next line, we decided to design and develop the manufacturing processes ourselves. For this, we needed powerful, reliable base machines."


Powerful and reliable

They found the right partner with the Starrag Group, as Hubert Singer confirms: "Our cooperation in the area of CWK machines showed us that we can rely on this supplier and that the machine concept is perfectly adapted to our production philosophy." So Feuer powertrain equipped the next line with the successor of the CWK 500 D, the HEC 630 D, which had just been launched on the market at the time. The horizontal, four-axes machining center belongs more to the class of the smaller, dynamic range of Heckert, but due to its "XXL travel paths" in the axes already provides a gateway to the medium-sized segment. In the past, this was expressed as well in the machine designation – HEC 500 XXL. Today it bears the name HEC 630 D, although the machine data was further optimized in regard to the customer benefit: The working space offers a clamping area of 500 x 500 mm and allows a workpiece interference range diameter of 1,000 mm. The pallet can be loaded with heavy components weighing up to 1,000 kg. Digital AC servo drives in conjunction with pre-tensioned ball screws with double-sided bearings provide a high dynamic range in the linear axes. They permit speeds of 100 m/min in connection with accelerations of 10 m/s2 in all axes. The working spindle is optionally available as a motor spindle with speeds up to 20,000 rpm or - for increased torque - with a hollow shaft motor. The NC rotary table has a direct drive with 100 rpm thus also guaranteeing shortest positioning times in the B-axis.

However, the performance data are of secondary importance at Feuer powertrain, Fikret Ersindigil explains: "We only use a fraction of the spindle power. Of more importance to us are the axis accelerations and quick tool changes to reduce unproductive downtimes. The simple operation of the tool magazine parallel to machining is also ideal for us." Of particular value to Fikret Ersindigil is the high process reliability and availability of the Heckert centers as a basis for high quality and profitability. He stresses: "The machines have a very stable construction; they last forever for our applications. At least we have machines that have been in operation around the clock for eight years and still show no signs of significant wear and tear."

Highly versatile

The range of functions of the HEC 630 D covers five different processes: cutting to length / centering, oil passage drilling, drilling of balancing and weight reduction holes and end machining. The inserting of the oil passage is a particularly challenging task. They are drilled from the main bearing through the crank webs to the pin and big end bearings, so that the crankshaft can be lubricated during operation at the important points. The channels are up to 200 mm long and have a diameter of 5 mm. Fikret Ersindigil knows all about the challenges of this deep hole drilling: "Such complex processing would have been unthinkable in the past on a standard MC. We had to invest a lot of know-how in order to get this application running reliably on the machine. But now the process runs perfectly, thanks to a hydraulic clamping device with integrated NC axes that maneuvers the component into the correct position. The HEC machining centers are equipped with appropriate hydraulic coupling points, and the NC axes enable integration into the CNC, so that this task runs automatically."
The appliances, which can be used for different workpiece sizes, are used to insert the balancing and weight reduction holes. The reason for this is the saving in weight, which is achieved with drill holes in the shaft and the crank webs, and makes an increase in performance possible. However, these processes only make sense with high-performance engines.

Service - a cost-saving component

For the five processes mentioned, Feuer powertrain uses the HEC 630 D in the standard version - with one small extra: In the machines for the oil passage drilling, the X axis was extended by 50 mm. "Heckert offers this as an option, saving us the need for larger machines" says process optimizer Ersindigil. He is highly satisfied with the service of the Chemnitz machine tool manufacturer in every respect: "This starts with the in-depth consultation before purchasing and continues with the professional handover and rapid assistance during ongoing operation." Fikret Ersindigil names a concrete example: "If I report a fault in the morning, the spare part is usually supplied later the same day, so the machine can resume operation at night." He also praises the remote maintenance and telephone support: "I always deal with professionals and not with call-center staff who have no idea about technology." Ultimately this saves nerves, time and money - and contributes decisively to a long-term, satisfied partnership.