Complete Machining

Complete Machining as an Investment in the Future

| Author/ Editor: Manfred Lerch* / Alexander Stark

As batch sizes become smaller, product cycles shorter and components more complex, companies are increasingly opting for complete machining in one clamping.

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The swivel head unit offers numerous advantages with regard to the complete machining, for instance of cube shaped components.
The swivel head unit offers numerous advantages with regard to the complete machining, for instance of cube shaped components.
(Source: Heller)

Complete machining requires a corresponding product range and solution competence from machine manufacturers. Heller has been rising to this challenge for decades and is therefore relying on a fifth axis in the tool of the 5-axis machining centers in the F series, and on the fifth axis in the workpiece of the HF series, on the other hand.

Now the customer base and with it the range of parts is changing continuously, both for in-house production and for contract manufacturing. This is why it is particularly important to be flexible and efficient when investing in machining centers. The people responsible at Schleifring in Fürstenfeldbruck were aware of this fact. When selecting a new machining center, however, stability and quality were the priorities. When machining partly filigree components, the machine had to be absolutely stable and not vibrate or oscillate. Although a 4-axis machining center would have been perfectly sufficient for the range of parts manufactured in Fürstenfeldbruck, Heller opted for the 5-axis machining center FP 4000 from Heller. This was because they wanted to invest in the future as well.

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The 5-axis functionality is now also being used and has even become indispensable for a certain range of parts. The filigree components, on the other hand, have consistently exhibited positive results thanks to the stable swivel head unit with speeds of up to 10,000 min-1 and a torque of 242 Nm. At Schleifring, 80 % of the workpieces are now manufactured from cast aluminum, stainless steel, non-ferrous metals and composite materials. Trochoidal milling has been used for a year now - especially for machining aluminum castings. This does not require high speeds, but rather feeding over the entire length of the cutting edge, high feed rates and a reliable control system. Brush block carriers and housings in diverse dimensions are therefore now exclusively processed on the FP 4000. For those responsible at the company, the use of the FP 4000 machining center required a profound rethinking process, but it turned out to be worthwhile. The manufacturer now covers the entire workpiece spectrum and has increased efficiency and output noticeable.

The PMW company in Weissenhorn took a completely different approach to investing in a 5-axis machining center. Initially, the two 5-axis FP 4000 machining centers had delivered very good results. However, PMW's requirements have been extended regarding dynamic and simultaneous 5-axis machining. The machine concept had to fit the respective workpiece in order to manufacture even more economically. This is why PMW was one of the first companies to opt for the HF 3500 5-axis machining center. Accordingly, the fifth was expected to result in advantages for a certain range of workpieces. Due to the complexity of the workpieces, this includes the large interference contour. When developing the machining center, Heller did not only integrate a single part clamping, but also created the possibility of multiple clamping and the machining of very large components.

Despite the large interference contours, there are hardly any restrictions on the degrees of freedom. Accordingly, the A axis can be tilted from 150° (30 to -120°). A further criterion at PMW was that the fifth axis was designed as a bridge with a counter bearing. This was important, because it allows the use of fixtures or clamping towers of up to 200 kg and more. If a deflection occurred, neither the necessary precision nor the corresponding repeat accuracy could have been achieved in the long term.

Fully Automated Cell Including MRK Robot

The company ZSO Zerspanungs- und Systemtechnik in Oberstaufen also deals with economical complete machining in one clamping. But there, it was more the "inner" values of the HF 3500 that counted. Specifically, the aim was to make the machine easier to operate, to integrate it into a fully automated cell including a collaborating robot, and to ensure transparency within the network. In the event of customer complaints, processes had thus be traceable at all times. The system is now fully networked. Access is possible via Intranet and Internet. Programs are uploaded via a network and workpiece and component drawings are uploaded to the monitor of the 24" touch screen via document management. In addition, Heller's service department now regularly accesses machine condition data and plans preventive maintenance and repair measures.

Time Savings and Additional Capacities

Manufacturing processes that are not necessarily typical for a machining center, but that contribute to complete machining, also offer added value. At Heller, this includes complementary technologies such as grinding, impacting, honing and turning. Especially the combination of turning, milling and drilling in all spatial positions was a major point during the development of the C series. The fifth axis in the tool is optionally available with extremely rigid swivel head geometry or flexible fork head kinematics and universal functionalities. Thanks to these features it enables highly productive machining with dynamic cutting values.

Turning and milling in one clamping were also important for Konstandin in Karlsbad in the production of cylinders with diameters up to 800 mm. After an intensive benchmark, the CP 4000 machining center met all these requirements. The aim was to rotate the outer and inner contours of different materials horizontally and vertically. Whereas Konstandin originally expected a milling to turning ratio of 80 to 20 %, the CP 4000 now offers 60 % milling and 40 % turning due to its high cutting performance and universal application. In Karlsbad, this shift results primarily from the machining of large components, which take up to three hours to turn. The possibility of milling and turning diameters of up to 900 mm and a maximum height of 1000 mm in one clamping means that more and more workpieces are now being transferred to the CP 4000. In addition, the newly defined flexibility has resulted in enormous time savings and has created additional capacities.

Implementing Machine Concepts Together with the Customer

Machining centers are only one part of the entire manufacturing process. This is why such interesting machine concepts can only be implemented in cooperation with customers and companies that have a technological lead and the appropriate solution competence.

The basic prerequisite for innovative extensions at Heller is always a solid basis: the 5-axis machining centers of the F and HF series and the milling/turning centers of the C series as well as the 4-axis machining centers of the H series. The fact that complete machining is also possible with a 4-axis machining center of the H series is demonstrated by Lindenmann in Blaustein. The fixtures are manufactured in such a way that four axes are sufficient for machining and integrate technologies such as engraving, impacting, interpolation turning, honing and grinding into the centers. Corresponding angle drill heads are used for the production of inclined bores.

Machining Centers Must Be Efficient Throughout Their Entire Life Cycle

This means that complete machining has long since arrived in the production halls. The Heller company has taken a clear stance: Machining centers must not only meet current requirements but must also be able to be used efficiently throughout their entire life cycle. Accordingly, Heller has built up competences in application engineering in order to meet market requirements in the future too. By investing in a machining center from Heller, customers are also investing in tomorrow's technologies.

This article was first published by MM MaschinenMarkt.

Original by Victoria Sonnenberg / Translation by Alexander Stark

* Manfred Lerch is a freelance editor of the editorial office Lerch in 70794 Filderstadt. Further information: Gebr. Heller Maschinenfabrik GmbH in 72622 Nürtingen, Phone (0 70 22) 77-0, info@heller.biz

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