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Products and solutions, 2000-03-20, 01:00 AM

Production Systems segment: Hüller Hille enjoys success with new cutting fluid technologies

A German car manufacturer has ordered an agile manufacturing system comprising eight SPECHT Z500T high-speed machining centers for one of its plants from Hüller Hille GmbH, Ludwigsburg, Germany. Hüller Hille designed the SPECHT Z500T specially for dry machining with micro-lubrication. In the past, dry machining centers of this kind have only been used as stand-alone machines; the recent order marks the first ever use of such machines in an interlinked system for volume production.

The agile system will produce wheel knuckles. The eight SPECHT machining centers are split into four independent cells, each loaded and unloaded by a robot. The ultimate production target is 1,400 wheel knuckle sets per day. The cycle time for one wheel knuckle set is 43 seconds. Each of the SPECHT Z500T centers requires a maximum of 80 milliliters of cutting fluid per hour. By way of comparison, machining centers using conventional cutting fluid technology employ about 300 liters per minute. Micro-lubrication therefore enables customers to make major savings: up to 17 percent of unit costs on machines with conventional lubrication can be attributed to the purchase, cleaning and disposal of cutting fluids.

The decision to use dry machining technology in volume production was based on its experience with two SPECHT Z500T units which the car manufacturer has been operating on a stand-alone basis for around one and a half years. As genuine dry machining centers designed to meet the requirements of micro-lubrication technology, the two SPECHT Z500T units have proved a great success at DC.

In developing the machining centers Hüller Hille came up with optimal solutions in particular for chip removal and fluid supply: the workpiece is suspended in the SPECHT Z500T and there are no corners or edges in the machine bed where falling chips could get caught. This eliminates the need for large amounts of fluid to evacuate the chips. To ensure that the cutting fluid is applied exactly to the contact faces between tool and workpiece, the emulsion is fed directly through the spindle of the SPECHT Z500T and sprayed onto the workpiece. Both this solution and the suspended machining of the workpieces have been patented by Hüller Hille.

Hüller Hille also offers cost-effective solutions for all processes and cutting fluid technologies employed in the high-volume machining of magnesium. For example, last year another German car manufacturer commissioned Hüller Hille's Ludwigsburg plant to install an agile manufacturing system comprising twelve units to machine magnesium transmission cases. The system uses oil as a non-water-miscible cutting fluid. Hüller Hille also offers the technology required to allow the safe use of emulsion as cutting fluid for processing magnesium on high-speed machining centers from the SPECHT series.

The use of magnesium in automobile production is on the increase, but the material is readily flammable during machining and thus places special demands on safety. These demands are particularly high when using micro-lubrication. Hüller Hille has developed a new safety concept for these applications which utilizes light and heat sensors as an early warning system along with newly available extinguishants. Approval was recently given by the "Berufsgenossenschaft Eisen und Metall II" employers' insurance association.

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