LEWA Attendorn relies on STARK Spannsysteme Minimising setup times Increased flexibility, setup time minimisation, increased productivity and the related time savings are profit-making factors for commercial success these days. Due to the ever increasing variety of parts, the usage of widely varying materials of widely varying dimensions and the need to be able to quickly and promptly satisfy customer requirements, at Lewa Attendorn it was considered necessary to optimise the machining section and make it more cost-effective. Lewa Attendorn GmbH, a medium-sized business with more than 150 qualified staff is a turnkey supplier for demanding custom solutions in the area of pipe shaping technology, advanced robot systems and a partner for the CNC manufacture of complex turned, milled and bored parts. In the vocational training centre alone, Lewa trains up to 220 trainees for local industry along with its own trainees in the wellequipped training workshop and as a result is the largest vocational training centre in the region. The tasks the business undertakes range from drilling and milling jobs, turning and grinding to complete robot welding systems. 1
Modern production systems and machinery operate ever faster and more efficiently. The systems are increasingly operated at the limit or even over the nominal limit. To counteract this situation and while searching for potential for optimisation and savings, at Lewa it was concluded that the only solution was to shorten the setup times and to do this by using a zero point clamping system. On what are do manufacturers concentrate today to be more cost-effective? In the reduction of non-productive time, that is minimising the setup times to make manufacturing more cost effective and as a result more competitive, says Rainer Frisch, head of machining in production at Lewa Attendorn. So the search started at Lewa for the right zero point clamping system manufacturer. After considering all the well-known providers, the team at Lewa Attendorn decided for the zero point clamping system manufacture by STARK Spannsysteme in Goetzis, Austria. STARK Spannsysteme is part of the Römheld Group and is one of the world s leading suppliers of zero point clamping systems. At the start we were very concerned, as we had a zero point clamping system from another manufacturer in use on a machine and had problems with inaccuracies and the mounting plates had become distorted. On one occasion the entire machine was suspended from the crane hook as the operator could not see that the workpiece was still clamped, explains Rainer Frisch. Robert Hartmann, head of sales at STARK Spannsysteme, was however able to very quickly clear up these doubts: On the STARK system the release is hydraulic, as a result the pallet is raised on release and the operator can clearly see that the pallet has been released. On other systems there is only simple locking and the operator has no indication of whether the workpiece is clamped or released. The team at Lewa also had the opportunity to view the zero point solution from STARK live on site at another organisation and to talk to the responsible machine operators in this organisation, which further reinforced their decision for the STARK zero point solution. Speedy zero point clamping system Initially STARK equipped one DMU 100 at Lewa with the Speedy 2000 zero point clamping system. Here it was decided to use a modified octuple design with a somewhat larger spacing to achieve better turning moments. On this system the retractable nipples are fixed positively and with high precision by spring force. Release is hydraulic. Thanks to the special nipple shape, there is no damage to the fits during the pallet change. As the clamping cycle on this machine is frequent, it was possible to significantly reduce the clamping time in a very short time and as a result considerably increase the productivity of the machine. Once Lewa was fully satisfied with the quality, the accuracy, the clamping process and the setup time, two further DMU 100 were also equipped with STARK clamping systems, as well as a large Wotan boring machine. On this Wotan machine, e.g. frames for bogies or complex cast structures or welded structures are manufactured in small production runs or as one-offs from face milling and shoulder milling with high feed rates to boring, thread cutting and reverse countersinking. 2 Three DMU 100 and the Wotan boring machine for manufacturing large parts
DMU 100: optical release check Thank heavens for hydraulics! The Speedys lift the pallet on release. Thus safe handling is guaranteed. Wotan: machine table with right-angled clamping plate 1 and right-angled clamping plate 2. Loading is undertaken using the overhead crane. The third hand function and optional clamping check are also an advantage during handling like the optical release check. Setup and storage stations: handling is crucial with large parts: the pallet for the Wotan is turned for setting up Wotan: machine table with right-angled clamping plate 1 and right-angled clamping plate 2. Loading is undertaken using the overhead crane. The third hand function and optional clamping check are also an advantage during handling like the optical release check. Capacity gain and more flexibility during the manufacture of large parts In collaboration with STARK, it was decided at Lewa to equip the Wotan machine with the Speedy 3000 zero point clamping system. During this process 5 rails each with 3 Speedy 3000 were attached to the machine table (2000 x 2500 mm). The reinforced version used here permits a maximum load of 25 t (!). Either pallets or workpieces can be placed directly on these rails. In addition, a Römheld hydraulic unit was also supplied for the clamping and releasing; this unit also has an integrated third hand function. STARK systems with the third hand function keep the workpiece or the pallet in the correct position once securely engaged. Workpieces and pallets are then secured against falling out and no longer need to be held by the operator. The system is also prepared for the clamping check option that can be easily added later. Here we have a right-angle clamping plate 2500 mm high. At the moment 2 clamping plates are fitted, one 1600 mm wide and the other 1200 mm. The clamping plates have been equipped with the retractable nipples. Speedy 3000 are also installed in turn on the clamping faces on the 3
right-angle clamping plates, so the pallets can be changed quickly, explains Rainer Frisch; Robert Hartmann adds: The entire zero point clamping system from STARK is a modular system. Small, medium-sized or large pallets can be clamped by using the narrow clamping plate and the wider clamping plate or by using both clamping plates, and there is access to the workpiece from all three sides. The clamping frames that Lewa uses here are 2.40 m high and 3.50 m wide and weigh approx. 3.5 tonnes, with the workpiece alone weighing approx. 1.2 t. For us the situation is much easier and we gain an immense amount of time. We have reduced the setup time by several times over and can now even produce on the machine with 3 shifts, which of course brings a capacity gain. Before we lost a large amount of time during setup and during clamping on the clamping plate. We spent approx. 5 hours setting up and clamping alone and the machines were stationary during this time, says Rainer Frisch. By using the zero point clamping system from STARK, at Lewa it is now possible to clamp the workpieces that are to be machined next at the same time as workpieces are machined. A dedicated setup station in front of the machine has been established for this purpose. While the workpiece is machined, we are setting up, as a result we do not lose any time any more and everything is also considerably more convenient, adds Rainer Frisch. Lewa application report fact box Taurus Wotan Cutmax3 PT boring machine Machine table with STARK zero point clamping system: Machine table dimensions: 2000 x 2500 mm Max. table load: 25 tonnes Configuration: 15-times spacing 600 x 600 mm 37.5 tonnes 450 kn Release pressure: 40 bar using hydraulic unit supplied Options: optical release check (lifting function) Right-angled clamping plate 1 with 12 STARK Speedy classic 3 zero point clamping systems Dimensions (WxDxH): 1600 x 1000 x 2500 mm Configuration: 12-times spacing 600 x 600 mm 30 tonnes 360 kn Release pressure: 40 bar using hydraulic unit supplied Options: third hand function using hydraulic unit Prepare for clamping check Optical release check (lifting function) Right-angled clamping plate 2 with eight STARK Speedy classic 3 zero point clamping systems Dimensions (WxDxH): 1000 x 1000 x 2500 mm Configuration: 8-times spacing 600 x 600 mm 20 tonnes 240 kn Release pressure: 40 bar using hydraulic unit supplied Options: third hand function using hydraulic unit Prepare for clamping check Optical release check (lifting function) DMU 100 P duoblock five-axis milling machine (three machines) Machine table with STARK Speedy classic 2 zero point clamping system Machine table dimensions: ø 1100 x 900 mm Max. table load: 2 tonnes STARK Speedy classic 2 Configuration: 8-times spacing 240 x 240 mm 8 tonnes 160 kn Release pressure: 40 bar using STARK pressure booster supplied Options: optical release check (lifting function) 4
Conclusion With the procurement of the zero point clamping systems from STARK, Lewa is continuing its drive for perfection, quality and adherence to deadlines. Thanks to the additional capacity, flexibility and the reduction in the setup times, at Lewa it has been possible not only to achieve increased parts accuracy, the processing times have also been significantly reduced. This time saving of course represents a significant competitive advantage and Lewa is now able to better meet customer s technical, schedule and also economic requirements. Rainer Frisch: We are very satisfied with the collaboration with STARK. Starting from the constructive meetings during the planning phase to the service and support on site. Finally everything hinges on a single point: to reduce the downtimes to be more cost-effective and increase the turnover and we have achieved this goal with the zero point solution from STARK, explains Hermann-Josef Bettendorf, member of the senior management and head of sales at Lewa, in conclusion. STARK Spannsysteme GmbH Based in Goetzis, Austria 30 staff (Römheld Group: 580 staff with an annual turnover of around 90 million euro) Metal machining sector. Developer and manufacturer of products and systems for efficient manufacturing. Emphasis Products focused on quality. Strengths Specialist consultation and comprehensive service. www.stark-inc.com www.lewa-attendorn.de Sources: Lewa Attendorn GmbH, Gildemeister AG, Taurus Wotan, STARK Spannsysteme GmbH, Römheld GmbH Photographs: STARK Spannsysteme GmbH i.v. (authorised signatory) Robert Hartmann, STARK Spannsysteme GmbH 5