The manufacture of extruder gearboxes is an important business area for the Upper Austrian company. A high level of vertical integration allows the greatest possible flexibility and the means to achieve short lead times despite a wide variety of individual customer requirements. In 2015, Eisenbeiss decided to invest in a large machining centre in order to increase both capacity and productivity. An existing machine, which is over 20 years old, will make way for the new machining centre. “We have limited space available on our site. We had earmarked a certain area of the building for the machine to further optimise the production process. Finding a concept that would fit was a particular challenge. Another decision was whether to choose a machining centre with four or five axes. To aid this decision, we provided an overview of the available and upcoming machines at the 2015 EMO trade fair in Milan. We looked in detail at six concepts from different manufacturers, and the final decision was between just two”, recalls Johann Panzenböck, Group Leader for Cubic Manufacturing at Eisenbeiss. A series of criteria were applied to evaluate the machines. The machining centre itself, a large tool magazine and a set-up point needed to be accommodated in the limited 8.5 m × 7.5 m space. Ideally, there also needed to be enough space available for handling large workpieces. “For us, though, the essential criterion was whether the new machine would allow us to process a particular gearbox housing, known internally as ‘part 7’. We passed this framework to the respective machine manufacturer and asked them to present a suitable space concept”, continues Panzenböck.

The described benchmark part is a gearbox housing produced as a cast blank part. With a 2,000-kg clamping weight and dimensions of 1,715 × 1,200 × 800 mm, it rotates in a 2,000 mm circle. Part of the requirement was that it must be possible to fully rotate this part. “In assessing the requirements, we realised very quickly that we would be unable to implement this with any of our standard machine versions. That is why we selected the Heckert machine as the basis for our concept since it meets the needs of our customers through its modular design. The size of the part would have required a Heckert HEC 1250, but there was insufficient installation space for this machine. An X-axis from the Heckert HEC 1000 was therefore used as a support system, and this was expanded with the Y-axis and Z-axis from the 1250. This created a processing area of 1,700 × 1,500 × 1,850 mm (X / Y/ Z). The clamping surface measures 800 × 1,000 mm with a height of 1,650 mm. The maximum workpiece weight is 4,000 kg. A 125 mm spindle sleeve with 500 mm travel path was implemented as an additional ZP-axis”, says Arno Berger, Sales Engineer at Starrag, describing the concept. 

“The Heckert HEC 1000 could not have offered the required size of interference circle if used as the basis. A workaround for this was to open the loading door when rotating the component. In programming terms, this meant a safety step had to be inserted to prevent rotation while the door was closed. The machine operator must actively confirm when starting the machining that the part is not oversized in order to keep the door closed. The upstream set-up point also has an access lock so that part movement is stopped immediately upon entry to the safety area”, Berger explains further. 

The system is complemented by a tower magazine, which offers space for over 300 tools. These can be up to 340 mm in diameter and 800 mm in length. With a spindle power of 55 kW and torque of 2,470 Nm, which is transferred to the tool via an SK50 interface, the machine has plenty of power reserves. The set-up point allows parts to be prepared in two places. Two longitudinal and one transverse conveyor ensure smooth chip removal at the front side of the machine.