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Market conquered with flexibility

Modern crankshaft manufacturing takes place on Starrag Group machining centres

With delivery times of weeks instead of months, the crankshaft manufacturer Feuer powertrain managed to conquer the European market and become one of the leading players in the world in less than ten years. The key to its success: consistently moving away from the previously conventional production of crankshafts on special-purpose machines. Instead, the production lines consist of machining centres – such as the horizontal HEC 630 D from Heckert – which makes production fast, flexible, high quality and ultimately profitable.

Crankshaft manufacturing is seen as the supreme discipline in metalworking. After all, the central component of a combustion engine requires 20 to 50 machining processes before it is ready for use – depending on the size and requirements of the respective engine. Feuer powertrain produces cast and forged crankshafts of 300 mm to 1,400 mm length in small and large batches for classic car engines of VW, BMW, Audi, Ferrari, Jaguar, Maserati, GM and others, as well as for the high-end twelve-cylinder engines of Bentley and Rolls-Royce. They are not only popular in the car industry: they can also be found in trucks, industrial engines, ships and generators.

The workforce of approximately 650 employees at the headquarters in Nordhausen in the Thuringia manufacture up to 1.5 million crankshafts a year and supply customers all over the world. The new plant in Tunica in the US state of Mississippi, which is due to start production this year to supply the American market, will ensure further growth. This will be followed by a production facility in Asia, and further building work is also planned in Nordhausen. And so the success story continues. Finally in 2003, the eponymous founder of the company Dieter Feuer, his partner Bernd Gulden and Managing Director Oliver Wönnmann stepped in to revolutionise crankshaft manufacturing with their new company “Feuer powertrain”. They wanted to use great flexibility and speed to conquer the market and become the market leader in Europe by 2010 – which they did. With an annual turnover of around EUR 150 million, Feuer powertrain is now even one of the four leading suppliers in the world.

Machining centres are replacing special-purpose machines

The Feuer powertrain team actually managed to completely redesign the production of crankshafts. For a long time, only special-purpose machines were used to carry out the varied machining operations that a crankshaft requires. These include cutting to length, centring, turning, milling and turn-broaching, deep-hole drilling, surface rolling and roller levelling rolling, rolling, double-headed orbital grinding, fine balancing, polishing and thermal treatments. Various measuring and checking procedures must also be carried out before the product is ready for dispatch.

Special-purpose machines are expensive to buy and inflexible in terms of machining, so using them is only worthwhile in large-scale production. With small and medium-scale production, the unit costs reach an almost unaffordable level. That is why the Feuer powertrain team looked for – and found – alternatives: all production lines in the five plants now established at headquarters in Nordhausen consist entirely of linked Heckert machining centres. They differ only in their complexity and number of stations, as some tuning tasks are only required in the high-end category. The degree of automation also varies. While on production lines for smaller batches of 1,000 or 10,000 units, the employees intervene manually at one point or another if necessary, 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.

A common feature of all production lines is that they can be adapted quickly and with little effort. This allows qualified employees to respond very quickly and flexibly to new orders. An important success factor, as emphasised by Managing Director of Technology Hubert Singer: “When others need an average of six to eight months, we are ready to deliver after just eight weeks. With our manufacturing concept based on machining centres, we have found the balance between productivity and product variety.”

Standard machines and  self-developed processes 

There are over 300 machine tools in continuous operation in Nordhausen, 24 hours a day, seven days a week. 42 of them were made by Heckert. This cooperation has existed since 2007. Fikret Ersindigil, Head of Process Optimisation, recalls: “At that time we were starting to shift production to machining centres. To complete a rush order, we urgently needed three machines for drilling and milling work, and Heckert was able to supply us with these immediately.” These machines were the CWK 500 D horizontal centres, which Feuer powertrain incorporated into a semi-automated stand-alone solution for urgent, small-scale production. “We were therefore able to fulfil this order and at the same time gain experience with Heckert machines,” explains Fikret Ersindigil. After all, he and his colleagues were still looking for suitable equipment suppliers for the new concept. “Our first attempt to transfer a production line to a machine tool manufacturer as a turn-key project did not go quite as we had expected”, reports the process specialist. “So we decided to develop and set up the production processes ourselves for the next line. For this we needed powerful, reliable basic machines.”


Powerful and reliable

They found just the partner they were looking for in the Starrag Group, as Hubert Singer explains: “The cooperation regarding the CWK machines demonstrated that we could rely on this supplier and that the machine concept tied in very well with our production philosophy.” Feuer powertrain therefore fitted the next line with the successor to the CWK 500 D, the HEC 630 D, which was brand new to the market at that time. The horizontal, four-axis machining centre is part of the fairly small, dynamic series from Heckert, but due to the “XXL traverse paths” in the different axes, it opens up the way to the medium-sized segment. In the past, this was also expressed in the name of the machine: HEC 500XXL. Today it is known as the HEC 630 D, and the machine data has been further optimised with regard to customer benefits: The working area offers a clamping surface of 500 × 500 mm and allows a workpiece interference diameter of 1,000 mm. The pallet can be loaded with components weighing up to 1,000 kg. The high level of dynamism in the linear axes is provided by digital AC servo drives in combination with pretensioned ball screws supported on both sides. These allow speeds of 100 m/min combined with speeds of 10 m/s2 in all axes. As a work spindle, a motor spindle with speeds of up to 20,000 rpm and – for increased speeds – with a hollow-shaft motor is optionally available. The NC rotary table has a direct drive delivering 100 rpm and therefore guarantees the shortest positioning times, including in the B-axis. The power data is now only of secondary importance for the usage at Feuer powertrain, explains Fikret Ersindigil: “We only use a fraction of the spindle power. More important to us are the axis acceleration rates and the fast tool change in order to reduce unproductive times. The simple operation of the tool magazine during the machining time also suits us well.” Fikret Ersindigil also considers the high level of process reliability and availability of the Heckert centres to be particularly valuable as a basis for high quality and profitability. He goes on to emphasise: “Conceptually, the machines are built to be so stable that they last forever with our applications. At any rate, we have machines that have been in operation round the clock for eight years and still do not exhibit any significant wear.”

Safety: “Conceptually, the machines are built to be so stable that they last forever with our applications.”

Versatile

The tasks of the HEC 630 D cover five different processes: cutting to length/centring, inserting oil channels, bearing relief, stroke relief and end machining. One particularly challenging task is inserting oil channels. These are drilled from the main bearing through the crank webs to the pin and conrod bearings so that the crankshafts can be lubricated in operation at the important points. The channels are up to 200 mm long, with a diameter of 5 mm. Fikret Ersindigil is aware of the difficulty of these deep-drilled holes: “Such complex machining would previously have been inconceivable on a standard machining centre. We had to invest a great deal of expertise to get the process safely onto the machine. But now it runs perfectly thanks to a hydraulic clamping device with integrated NC axes, which puts the component in the right position. The HEC machining centres are fitted with appropriate hydraulic coupling points, and the NC axes can be incorporated into the CNC control technology, so that this task is also automated.”

The fixtures, which can be used for different workpiece sizes, are also used for inserting the bearing relief and stroke relief. The reason for this is the weight saving that is achieved via the drill holes in the shaft (bearing relief) and the crank webs (stroke relief), enabling an increase in performance. However, these machining processes only make sense for high-performance engines.

Service – a cost-saving component

For the five processes mentioned, Feuer powertrain uses the standard version of the HEC 630 D – with one small addition: On the machines for making the oil channel holes, the X-axis has been extended by 50 mm. “Heckert offers this as an option, which has saved us having to buy larger machines,” says process optimiser Fikret Ersindigil with a smile. Overall, he is very satisfied with the service provided by the Chemnitz-based machine tool manufacturer: “It starts with sound advice before purchasing and continues with professional acceptance as well as fast assistance during operation.” Fikret Ersindigil continues: “If I report a fault in the morning, the replacement part is generally delivered in the course of the day, meaning that the machine can resume operation in the evening.” He also praises the support provided via remote maintenance or telephone: “I always get through to specialists and not call centre staff who have no idea about technology.” This ultimately saves stress as well as time and money – and contributes significantly to a satisfying long-term partnership. 

Hubert Singer (left), Managing Director of  Technology, and Fikret Ersindigil (centre), Head of Process Optimisation at Feuer powertrain, along with Dr Michael Fiedler, Head of Sales for Transportation & Industrial Components at the Starrag Group, are pleased with the successful partnership between the two companies.

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