Complete processing Investing in the Future

Author / Editor: Manfred Lerch / Mag. Victoria Sonnenberg

Ever-smaller batch sizes, combined with shorter product cycles and increasing component complexity, today necessitate continuous tightening-up of the production process. For this reason, numerous firms have now decided on complete processing in one clamping.

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The C series, with horizontal, vertical and angled turning functionality is interesting for increasingly small batch sizes combined with greater part variation, even without a pallet changer.
The C series, with horizontal, vertical and angled turning functionality is interesting for increasingly small batch sizes combined with greater part variation, even without a pallet changer.
(Photo: Heller)

Among machine builders, the prerequisite for complete processing is a corresponding spectrum of products and solutional competence. The firm Heller has been facing this challenge for decades now and has therefore relied on a fifth axis in the tool in its 5-axis processing centres of the F series, for example, yet preferring a fifth axis in the workpiece in the HF series. At the moment, continuous changes are taking place in both the firm’s own production and in contract production among its customers, so there are corresponding changes in the range of parts as well. It is therefore especially important in this context to focus on flexibility and efficiency when making investments in processing centres for the future. For those in charge of the firm Schleifring in Fürstenfeldbruck, this was clear. In selecting a new processing centre, however, the main factors were initially strength and quality. As filigree components were often processed, the machine should have an absolutely stable stance without vibrations or oscillations. Although a 4-axis processing centre would have been entirely sufficient for the range of parts made in Fürstenfeldbruck, the decision went in favour of the FP 4000 5-axis processing centre from Heller. Meanwhile, the 5-axis functionality is also being put to use and, in the view of the management, has become nothing less than absolutely essential for a certain range of parts. With the filigree components, in contrast, experience with the stable head unit running at up to 10,000 min-1 and a torque of 242 Nm has been positive in every way. Now Schleifring is processing workpieces consisting of up to 80 % cast aluminium, as well as stainless steel, NF metals, and composite working materials. For machining cast aluminium in particular, the firm has in the past year relied on trochoidal milling. For this, milling and high rotational speeds are no longer necessary; instead, the key factors here are in-feed along the entire cutting-edge, high feed rates, and the control system. Brush block carriers and housings in all dimensions are therefore now processed exclusively on the FP 4000. Although the management had to go through a far-reaching rethink in choosing the FP 4000 processing centre, today it has now paid for itself. They are now able to cover the entire range of workpieces with it and have measurably improved efficiency and productivity.

Machine concept should be suited to the workpiece

A completely different approach to investment in a 5-axis processing centre can be seen at the firm PMW in Weissenhorn. Initially, their experience with the two FT 4000 5-axis processing centres was entirely positive. When it came to dynamic and simultaneous 5-axis processing, however, PMW started to raise their requirements. The right machine concept was needed for each workpiece in order to enable even more cost-effective production. The firm has therefore become one of the first to decide on the HF 3500 5-axis processing centre. Correspondingly, they see themselves as having gained advantages with the fifth axis in the workpiece wherever a certain range of workpieces is involved. These include workpieces with a large interference contour due to their complexity. In developing this processing centre, Heller no longer assumed clamping of individual parts, but designed for the possibility of multiple clampings as well as the accommodation of very large components. Despite the large interference contours, limitations are seldom imposed on the degree of freedom. Correspondingly, the A axis can be swivelled through 150° (30° to -120°). A further decisive criterion for PMW was that the fifth axis is designed as a bridge with counter-bearings. This was important because the firm works with jigs and clamping towers weighing up to 200 kg and more. Any bending would in the long term have prevented achievement of the necessary precision and the corresponding repetition accuracy.

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Cost-effective complete processing in one clamping is also the goal of the firm ZSO Zerspanungs- und Systemtechnik in Oberstaufen. But the decisive factors here were more the “inner” values of the HF 3500. Concretely, the priorities were the simplified machine operation, the incorporation into a fully automated cell including a robot, and the transparency within the network. This would ensure process traceability at any time in the event of customer complaints. In the meantime, the installation has been completely networked, with access possible via intranet and internet. Programs are installed via the network, and workpiece component drawings are loaded onto the monitor of the 24” touchscreen via a document manager. In addition, Heller’s service staff regularly monitor machine status data and plan preventive service and maintenance measures.

Time savings and additional capacities

Production technologies which are not necessarily typical for a processing centre, but which contribute to complete processing, bring additional added value. At Heller, these include supplementary technologies such as grinding, slotting, honing, and also turning. Particularly important in the development of the C series was the combination of turning, milling and boring in all spatial positions. With the fifth axis in the tool, optionally available with an extremely stiff swivelling head geometry or with flexible clevis kinematics, and universal functionalities, highly productive machining with athletic cutting rates is possible. Turning and milling in one clamping were also required by the firm Konstandin in Karlsbad for manufacturing cylinders with diameters up to 800 mm. The processing centre CP 4000 faced demanding benchmarks and met all requirements. The goal here was to turn horizontal and vertical, external and internal contours in a variety of working materials. At Konstandin, the original assumption was of a milling to turning ratio of 80 to 20 %, but use of the CP 4000 with its high cutting performance and universal application has meanwhile led to 60 % milling and 40 % turning. In Karlsbad, this shift primarily resulted from the processing of large components, which might require up to three hours on the turning machine. Because of the possibility of milling and turning diameters up to 900 mm and maximum heights of 1000 mm in one clamping, they are in the meantime processing an ever-increasing number of workpieces on the CP 4000. With the newly defined flexibility, moreover, they now find they are making enormous time savings and thus releasing additional capacities.

Now, these processing centres are only one part of the entire production process. Interesting machine concepts of this kind can therefore only be realised in collaboration with the customer and realised by firms with exceptionally advanced technology and corresponding solutional competence at their disposal.

At Heller, the fundamental prerequisite for such innovative expansions is always the same basis, that is, the 5-axis processing centres of the F and HF series and the milling/turning centres of the C series, along with the 4-axis processing centres of the H series. The experience of the firm Lindenmann in Blaustein shows that complete processing is also possible with the 4-axis processing centre of the H series. The firm manufactures jigs in such a way that four axes are sufficient for the processing; technologies ranging from engraving, slotting and interpolation turning to honing and grinding have been integrated into the centres. To create oblique bores, suitable angled boring heads are employed.

In summary, it is clear that complete processing has long since become established in the production halls. So the topic is not new. In this field, the firm Heller has taken a clear position: it is not enough for processing centres to meet current demands, but they must remain efficiently usable throughout their entire life-cycle. Correspondingly, Heller has expanded its competence in application engineering so as to continue to meet market requirements in the future as well. That means that an investment in a processing centre from Heller is simultaneously an investment in technologies of tomorrow.

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* Manfred Lerch is a freelance author at Redaktion Lerch in 70794 Filderstadt. Further information: Gebr. Heller Maschinenfabrik GmbH in 72622 Nürtingen, tel. (00 49-70 22) 77-0, info@heller.biz

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