Machining wheel carriers - or 'knuckles' - is performed on a very flexible 'quad-type' manufacturing system based on vertical turning centres, machining centres, automation and robotic handling.

The manufacturing solution for the machining of wheel carriers, also called 'knuckles', adopted by Georg Fischer Automotive, Singen in Germany, is a prime example of productivity and quality on the smallest possible footprint. This particular 'quad-type' Manufacturing System is the brainchild of a team of highly experienced specialists from GF, EMAG and SW. All parties expect that this will create a 'bandwagon' effect, bringing in further large-scale orders for everyone concerned.

* Summary of the manufacturing system for front axle wheel carriers/knuckles.

Linear automation equipment and robots link up four radially arranged, flexible manufacturing cells - consisting, in the main, of two each of EMAG VSC 500 turning centers and one each SW BA 600-2 horizontal, twin-spindle machining center, i e, in total eight VSC 500 and four BA 600-2 - with an industrial washing machine, measuring cells and inkjet markers, to provide 880m2 of concentrated productivity.

* The rivalry between cast iron and aluminium - the rivalry between cast iron and aluminium has not yet been brought to a conclusion.

Cast iron materials are still eminently suitable for the conversion of automotive ideas into reality - provided the partner in the production of such components has a firm grip on the material and the processes involved.

It is being confirmed again and again that the use of light alloys does not always lead to the necessary reduction in weight, and especially not when the attendant requirements also include cost benefits.

Cast iron, however, still carries a creative weight potential, especially if one keeps in mind the availability of innovative ferrous alloys such as higher-tensile ferritic materials.

GF Automotive - the automotive sector of the Georg Fischer Group with a global workforce of 14,000 and its headquarters in Schaffhausen, Switzerland - sees itself as a member of a partnership of excellence in the field of modern, cast iron-based vehicle manufacturing solutions.

Continuous research and development in the areas of pressure die, sand and chill casting in iron, aluminium and magnesium are the kind of activities that are in high demand in development- and manufacturing-based partnerships with the automotive industry.

It gives the makers of vehicles access to a whole range of materials and manufacturing solutions for ready-to-install components.

Within the Swiss Group, the plant at Singen in the South of Germany - with its close on 1,300 staff and an annual turnover of EUR 220 million - is responsible for the manufacture of ductile cast iron components for passenger cars and commercial vehicles at a ratio of 50:50.

The 180,000 tonnes of cast iron parts produced annually are used to make chassis, steering and transmission components and also motors, the major customers being the important European car manufacturers in both branches of the industry.

It therefore did not come as a surprise that GF Automotive, Singen, received the order for the casting and machining of the two front axle wheel carriers for the BMW 1 series and also for the new BMW 3 series.

The larger size is intended for the high-powered vehicles and the smaller one for the entry-level models.

Once the 'run-up' period for the models has been successfully negotiated, a total annual number of 450,000 sets is to be delivered to the assembly plants at Dingolfing and Leipzig in Germany and also in South Africa with a lead time of just two to three days.

The complex front axle wheel rim geometry and the resulting variety of machining geometries would normally be an ideal case for the clever experts in special purpose machine construction.

However, although special purpose machines are available for every single requirement these days, they are often quite inflexible - when one of today's most important investment criteria for production tools happens to be flexibility.

* More flexible than special purpose machines - the specially conceived manufacturing solution to the requirements at Singen consists of highly productive vertical turning centers from EMAG, Salach, and horizontal machining centers from SW, Waldmoessingen - today part of the EMAG Group, and represents a neat bit of straight-forward, uncomplicated, partnership-based work, offering a high degree of productivity on a compact footprint of just 880m2.

Four radially arranged manufacturing cells ensure flexibility, each of them consisting of the following.

* Two EMAG VSC 500 pick-up vertical turning centers with integrated measuring system, special chucks and automatic workpiece handling.

* A SW BA 600-2 twin-spindle horizontal machining center with 2x4 clamping unit on a 5-axis double swivel trunnion.

* A FANUC R 2000-i 165F industrial robot with a swivel gripper able to accommodate both types of wheel carriers.

* An inkjet writer with optical recognition, which marks each component with its specific ident number.

* A downstream industrial washing machine cleans and protects the wheel rims against corrosion.

Georg Fischer has invested some EUR 10 million in this ingenious manufacturing system.

The price also covers: the elaborate special workholding equipment, the original tooling specification and - last but by no means least - the extensive process know-how.

* About the companies involved - in 2004, the Georg Fischer Group, with its headquarters in Schaffhausen, Switzerland, and its 12,300 staff worldwide achieved a consolidated turnover of approximately EUR 2.3 billion, of which EUR 1.1 billion were generated by the automotive sector with its workforce of about 5,800.

The Singen works employ 1,300 staff, achieving a turnover of EUR 220 million.

Half of their annual production of 180,000 tonnes of ductile cast iron is used for passenger car parts and half for truck components.

20% of them are complete machined and dispatched ready-to-install, another 20% are pre-machined and 60% leave the works as raw-parts.

The EMAG Group, with its headquarters at Salach, Germany, presently employs 2,000 staff, with a turnover of approximately EUR 430 million in 2005.

The Group includes the grinding specialists Reinecker (high precision internal grinding), Karstens (external production grinding), Kopp (grinding of cams and camschafts) and Naxos-Union (grinding of crankshafts), the laser specialist Lasertec and the automation equipment manufacturer Heilig.

Since mid-2004 SW Schwaebische Werkzeugmaschinen, Schramberg-Waldmoessingen/Germany (horizontal and vertical machining centers), with 265 staff and a turnover of EUR 70 million is also part of the EMAG family.

Since May 2005 the Group also includes the gear hobbing specialist Koepfer.

* Manufacturing system - comments - 'A technical availability of 95% for the complete system makes us very happy,' commented Jurgen Bolle, responsible for production planning and complete machining.

'We also reach the calculated efficiency level of 80% without any problem.

In fact, we are achieving an effective level of 85%,' he added with a smile.

Norbert Schnurr, the responsible project leader, asked the two machine manufacturers for a cycle time guarantee.

'It has since been more than just adhered to.

The system is highly flexible - not only with regard to changing batch sizes, but also when it becomes necessary to react quickly to component variations and new orders.' He also praised the excellent co-operation throughout the lifetime of the project between GF and BMW on the one side and the two machine tool builders, EMAG and SW, on the other.

* 19 shifts/week - owing to the fact that the BMW series 1 and 3 are in greater demand than expected, the plant is running to capacity.

In fact, it presently works 19 shifts a week - from Sunday evening to Saturday afternoon.

The total capacity of 450,000 sets of wheel carriers means that between 1,200 and 1,400 sets - or 56 skeleton containers full - are leaving for the BMW sites every day.

The blanks of the wheel carriers/knuckles, cast and protective-coated at Singen, are inserted into the workpiece receptors of the transport system and conveyed to the the VSCs.

One of the two VSCs within the four manufacturing cells complete-turns the wheel hub and mills, drills and threads the fixing points of the left wheel carrier, the second VSC the right wheel carrier, respectively.

Every fourth component is measured with in-process gauging equipment and, like the other three, inserted by robot into the SW twin-spindle machining center, where the linking points are high-precision milled and drilled.

The components are then washed and all crucial features and dimensions re-checked to intolerances on a central measuring cell.

Finally, an optically controlled printer marks every component with an identifying code.

To ensure that such large quantities of components are delivered on time and at the right batch sizes is not just a question of machine performance but also of organisational effort.

For this reason, a cell computer with SAP system is used to handle all communications and necessary data exchanges.

GF sees the performance, economic viability and perfection of this manufacturing system as the Group's successful entry into the mass production of completely-machined vehicular components.

Together with their acquired know-how in manufacturing techniques this surely provides GF with a decisive edge in the global cut-throat cost and quality competition of 'made in Germany' production components.