Two machining centers linked via a linear pallet system were to form the core element of the new flexible manufacturing. At the EMO 2011, the responsible CVS team visited a variety of machine tool manufacturers and obtained detailed information on relevant cutting solutions. Head of Production Schröter was surprised by the result: "Most manufacturers back then, especially suppliers from the Far East, had focused on fast, light machining, as required particularly in the automotive industry. For a medium-sized company like ours that conducts heavy-duty cutting in small batches, the range of offers was rather small, so we only shortlisted two suppliers."

Andreas Marterer defines the necessary cutting operations more closely: "We machine housings for compressors, valves and gearboxes, their corresponding covers and flanges, oil containers and the like - usually in batches of less than 30 units. 75% of the parts are made of cast iron and 20% of aluminum. The remaining ones are made of other materials." For cast iron processing in particular, the machining centers require maximum performance. "In our company, drill-finishing pump housings is the core operation. We use this type of machining for all bearings and housing bores, starting at a diameter of 30 mm up to 520 mm. For this we need a strong spindle that has to provide a torque of at least 900 Nm." Another key requirement was a tool magazine with more than 200 pockets and a changer that can also cope with large tools weighing up to 30 kg and more than 450 mm in length.

CVS decided to invest in two identically constructed HEC 630 Athletic horizontal machining centers from Heckert GmbH, which is part of the Starrag Group, Chemnitz. "The 630 model palette size corresponds to our preceding machines. While that is a bit tight, the available space in the production hall doesn't permit any larger machines." The comfortable working environment of the Heckert HEC 630 Athletic was all the more decisive. It enables a workpiece swing diameter of 1550 mm, and a maximum workpiece height of 1250 mm. "We have enough space for retracting and for table rotation, even with our large parts. What’s more, enough leeway remains for larger work pieces, which addresses the general trend with pumps", says Uwe Schröter.” 

The casting bed and thermo-symmetrical machine construction with its high rigidity also scored points for the Heckert-BAZ horizontal machining center. These factors are a fundamental requirement for progressive cutting performance and high precision. Profile rail guides in all linear axes, pre-clamped guide carriages and ball screws with counter bearing ensure accuracy is maintained over a long period. The steep workspace cover and the wide, centrally arranged chip conveyor contribute to the safe and rapid removal of even large quantities of chips - as well as the associated heat.

The restructuring took place in 2014 without disrupting production. This was achieved by first exchanging one machine and taking the pallet system into operation. Six months later, the second machine followed. Andreas Marterer is full of praise: "The scheduling and indeed the entire cooperation with Heckert and Schuler worked perfectly." Their experience so far with the new production plant has also been very positive, as production manager Schröter confirms. "We are currently using them in operator-controlled two-shift operation. If necessary, we will introduce an unmanned third shift. But first it is still necessary to optimize downstream processes right through to the assembly."

As far as machining is concerned, the goals have been met. Setup times have decreased by 50% and the processing times on the HEC 630 Athletic are around 10% lower than before. Planning Engineer Marterer is particularly pleased that he was largely able to take over the existing tools and programs as they stood.
In addition to the time saving, the new production plant also resulted in improved processing quality. For example, with the HEC 630 Athletic, CVS ​​effortlessly achieves the position tolerances of 0.04 mm required for screw compressors. Bore tolerances in the range of IT6 are also complied with, as is the necessary surface roughness of Rz = 6 µm. Uwe Schröter explains: "We subject our components to regular quality control. We inspect the critical dimensions of every fifth screw compressor, for example. Here we observed a trend towards a significant improvement compared to our previous production."