Portal milling center for machining gigantic workpieces

Thanks to a long-term management perspective, Maschinenfabrik Wüstwillenroth delivers large components from Germany to the whole world. With the investment in a portal milling center from Bimatec Soraluce, the company has expanded its own production and is constantly receiving new orders.

Often the connections of global trading stretch further than expected, and bring large orders to the most capable companies around the world. Physical distance does not matter if the technical conditions for cooperation are met.

This is demonstrated, for example, by Maschinenfabrik Wüstwillenroth GmbH in Birstein, Germany. In this township with just 6,200 inhabitants, the local company manufactures gigantic workpieces of which some are even delivered as far away as China.

The investment in a new portal milling center from Bimatec Soraluce made this possible. The PMG 14000 gantry-type machine offers maximum precision in the machining of large workpieces with travel ranges of 14,000 mm (X) lengthwise, 5,500 mm (Y) crosswise and up to 2,000 mm (Z) vertically. The heavy cast iron construction with optimum damping properties and the INA linear guiding systems with hydromechanical damping elements allow the machining of complex and high-precision workpieces. Thanks to the stepless indexable milling head, such workpieces can be machined precisely from five sides in just one set up.

Future-oriented investment leads to new projects

The company‘s courageous decision to invest in a large machine quickly paid off. „The investment was just right for us, because soon after that we had achieved a good machine workload for our portal machine. The market has the right components for it and of course we are delighted with the good number of orders,“ confirms Thomas Zinser as Managing Director of Wüstwillenroth.

With the new portal milling center, Maschinenfabrik Wüstwillenroth GmbH has successfully entered a new segment of the market. Up to now, the company had machined some of its largest components with three floor type milling machines from Bimatec Soraluce and further to this also uses two other machines from this supplier. With currently six machines from the same manufacturer, you can see a clear trend. Where does this come from? Managing Director Thomas Zinser explains: “Quality, support and service from Bimatec Soraluce have convinced us over and over again. The high level of transparency in our conversations and the honest interest in the customer are really unique”.

Independent consultation in a trusting partnership

“Once we bought a smaller machining center and even asked for the advice of our friends at Bimatec Soraluce, because we absolutely trust their expertise in technical consulting,” says Zinser. The available options included smaller machines with a longitudinal travel (X) of 1,000 mm. As a manufacturer of large milling and turning centers, Bimatec Soraluce does not offer these machines due to their small size. “We advised them to purchase a machining center with X = 1,080 mm, which exactly meets the requirements at Wüstwillenroth”, confirms Andreas Lindner, Managing Director of Bimatec Soraluce. The independent decision proved its worth and so Thomas Zinser and his father, Heiner Zinser, once again trusted Andreas Lindner’s advice when it came to investing in a machine, which could handle large components.

After the Zinser family had taken over the 75 year old company from a foundation, father and son worked on expanding the business in a sustainable way. Thanks to a future-oriented strategy of apprenticeship and the hiring of further new employees, the company expanded from 30 employees in 2008 to 55 permanent employees and 15 apprentices. As a further step in the expansion, the two managing directors had recently planned to purchase a new floor type milling-boring machine from Bimatec Soraluce. However, instead of processing the enquiry according to a standard procedure, the manufacturer from Limburg took the time to analyze important processes together with the management directorate and the production management of Wüstwillenroth in order to prepare an offer that corresponded to their actual requirements.

Since another, medium-sized machine would have limited the transportation paths in the existing hall, Bimatec Soraluce finally suggested to their customer not to make the planned purchase. “A good and honest relationship is more important for us than short-term sales”, states Andreas Lindner quite clearly. “We jointly considered that it made more sense to first optimize the flow of materials on the company premises. As a result, it was possible to install a large Gantry machine. And with our patented DAS⁺ system, it guarantees the highest surface quality for gigantic workpieces”.

The PMG 14000 portal milling center can be used to machine cubic and prismatic workpieces in a single setup. Its major advantage is the capability to be able to machine large components in their designated installation position. Since smaller machines usually have to machine big workpieces vertically, it can happen that these parts become distorted when installed in a horizontal position due to their own weight. Therefore it is particularly important to avoid this when machining large and heavy components. Experienced technicians always strive to carry out the machining in the installation position.

Highest precision and happy customers

In Birstein, the new PMG 14000 now allows the machining of gigantic workpieces in horizontal position. For instance, the gantry beams for a shipyard’s cutting system extend over a length of 33 m. Wüstwillenroth designs these in three components of 11 m each. Over this length, the guideways achieve an accuracy of 0.05 mm.

In mechanical engineering, Wüstwillenroth also handles 7 m long bars as needle holders for textile machines. Through another customer, the company is involved in the aircraft industry and produces fixtures for wing adapters. Wüstwillenroth also uses the PMG 14000 to machine high-precision cross slides for milling machines in the machine tool sector. These components are produced with impressive results of parallelism, angularity and flatness of 0.02 mm. Last but not least, the machining of complex gearbox housings also demands maximum precision. With dimensions of 2,000 x 2,000 x 1,000 mm, these large components are used in the production of mining excavators and maximum tolerances for the shape and position for the co-axial bores of the axes of 0,015 mm must be achieved.

This high accuracy is achieved at Wüstwllenroth by using a stepless milling head from Bimatec Soraluce. The automatic indexing head has a stepless indexing system and thus enables highest precision and positioning accuracy during machining. It can be positioned every 0,001° thus giving 360.000 positions per indexing plane. Also Hirth couplings are used in both indexing planes to achieve high stability and positioning accuracy in every position.

Since nowadays even large components are becoming increasingly lighter and more complex, Wüstwillenroth also uses the intelligent DAS⁺ system from Bimatec Soraluce. If mechanical vibrations occur during machining, DAS⁺ detects them using sensors and calculates counter-vibrations which are exactly opposite in frequency and amplitude. Actuators in the ram generate these counter vibrations which consequently eliminates any mechanical chatter during the machining process. Since both vibrations cancel each other out to the largest extent, the milling head runs with a unique smoothness. To further optimize the result, the system also adjusts the speed of the working spindle if necessary. On the one hand this reduces tool wear by 25 % whilst on the other hand reduces also the machining time by up to 45 %. All in all, this technology even allows the end users to achieve higher cutting performance of up to 300 %, whilst at the same time customers appreciate machined surfaces as smooth as glass.

Clamping times become machining times

“In addition to the interesting possibilities of a large portal machine, it was also the modern technology of the machine that convinced us”, explains Thomas Zinser and his father Heiner Zinser adds: “We have been working with Soraluce for a long time and are therefore used to very high standards, but the technological possibilities still don’t stop to impress me”.

Since large workpieces over 1 m³ often require time-consuming and costly alignment, it makes special sense to optimize this process when using a large portal machine. “Only when the spindle turns, our customers make money,” says Andreas Lindner. Therefore, Bimatec Soraluce has concentrated on the development of an automated system for measuring and aligning raw components. The patented VSET system is based on photogrammetry technology and measures the workpiece outside the machine.

Possible defects of the raw component can be detected and eliminated even before machining begins. Machine downtimes due to defective blanks are thus a thing of the past and there are no unnecessary production losses due to delayed decisions on reworking in the late or night shifts.

The VSET software finally creates a clamping plan of the workpiece. This plan contains detailed information about a reference point that the machine picks up with a probe before machining. This makes it possible to standardize and accelerate alignment procedures. VSET reduces the time required for best-fit calculation, measurement and alignment by up to 70 %. It is not without reason that this pioneering development was therefore awarded the Best of Industry Award.

Technology consulting for a smooth operation

Bimatec Soraluce assisted Maschinenfabrik Wüstwillenroth not only with hardware and technology, but also with the selection of a suitable software. The technology department helped with the selection of a suitable CAM system and actively supported them in the adaptation of post-processors. Today, the company in Birstein has two workstations for the use of Hypermill software, which in the shortest time creates detailed NC machining programmes.

In order to guarantee optimum use of the machine, Bimatec Soraluce trained the users in advance in its technology center in Limburg as well as in the Wüstwillenroth plant after setting up of the new machine. The focus was of course on the company’s own workpieces.