Advanced travelling column machining center for large parts
More throughput and higher quality
Machining centers often require more than just spindle power and axis speeds. In large parts, where the numbers are often very small, additional functions sometimes prove to be as significant as the actual cutting performance. At its new travelling column milling center, an Austrian mechanical engineering company has had good experience with a technology for eliminating chatter vibrations and with a method for optical measurement of the components outside the machine, which saves a considerable amount of time and costs.
“We are a modern high-tech company and our customers demand the highest degree of accuracy from us,” says Roland Haas, Managing Director of framag Industrieanlagen GmbH based in Frankenburg (Austria). With around 130 employees, the company manufactures high-quality machines and systems for industrial customers. The product range includes machine beds, test bench technology, saws for heavy duty applications, flame cutting technology, equipment and components for the production and processing of fibers as well as special machine construction. In addition, engineering services are provided and old machines are retrofitted for reuse. Framag has an outstanding position above all in the field of vibration damping. For this purpose Hydropol was developed, a special mineral-based material (not polymer concrete) that absorbs vibrations particularly well. Since the production takes place without resins and chemicals, the users need not worry about the subsequent disposal – the classification as “reinforced concrete” makes the professional disposal worldwide easy. Alternatively, framag workpieces are also taken back by framag at the disposal costs throughout their lives and disposed of properly. This is why a number of renowned machine tool manufacturers are purchasing their machine frames from framag. Another important business area of the company is the production of vibration-damped test benches for the automotive / commercial vehicle industry, railway sector or for other requirements throughout Europe. In the production of these components or machines, the highest accuracy and a tailor-made frequency spectrum with a defined oscillation amplitude and calculated decay behavior of oscillations are always required.
Replacement for an older travelling column milling machine
In 2015, consideration was given to replacing an 18-year-old travelling column milling center. When purchasing, it was a requirement to continue to use the existing foundation with as few changes as possible. Firstly a machine tool bed from framag could be integrated by the BIMATEC SORALUCE technicians and secondly the vertical traverse could be perfectly adapted to the existing floor plate. The same was true for the existing floor plate 10,000 x 3,500 mm – which could even be extended by about 1.5 m. A team of operators under the direction of the production manager Erich Preundler assisted the management in the preparation of the machine specifications and in the assessment of the incoming offers. After numerous discussions, in the course of which then also test machining had to be carried out, four potential suppliers were in the nearer selection. In a final round with the two best, the decision was made for the SORALUCE FP 10000 milling center.
Why BIMATEC SORALUCE were convincing
The decision for the offer of BIMATEC SORALUCE was not only due to the technology, but also because of the recognizable service readiness of the provider. The latter was already evident in the bidding phase, when BIMATEC SORALUCE was able to achieve 2,000 mm more travel in the longitudinal direction as a result of changes made to the foundation in advance. An important advantage for framag was the compact orthogonal milling head with its small dimensions. As this is a standard component, it can be exchanged for a loan head within 24 hours in case of service from Limburg. In addition, the FP series exceeded the competition with its Z travel of 3,200 mm and still fitted, from the height point of view, into the designated hall. Another advantage was the fact that, despite the small amount of space available, a tool changer with 120 magazine pockets could be accommodated. This aspect was also important because many individual workpieces have to be machined. Another decisive factor was the positive feelings of the decision-makers, who felt well advised by the SORALUCE specialists right from the start.
DAS-System – active chatter elimination
One of the most compelling arguments in favor of SORALUCE technology was its patented Dynamics Active Stabilizer (DAS) system. It is based on the fact that the mechanical vibrations of the milling head occurring during machining are detected by sensors. An electronic system then uses actuators in the milling slide to generate counter-oscillations that are exactly opposite in frequency and amplitude. Since both oscillations largely cancel each other out, the head moves its milling paths with a hitherto unrepresentable smoothness. At the same time, if necessary, the speed of the work spindle is adjusted. The result is an optimally quiet machining process. In addition, the machining conditions no longer depend on the position of the workpiece in the working space. Advantages include an increase in cutting performance of up to 300 % and a proven reduction in production time of around 45 %. Equally important is a better surface finish, an important aspect especially for sliding surfaces and guideways. Also, the wear on both the tool and the machine is noticeably reduced. The DAS system was already convincing during trial machining, as it provided better surface for the finishing of guideways compared to all other competitors. Further highlights of the SORALUCE control system are Adaptive Control, an automatic adaptation of the axis feeds in respect to the spindle load, as well as a whole series of practice-oriented user cycles that make the work easier for the user.
VSET – measuring and aligning outside the machine
After successful commissioning of the new travelling column milling machine VSET was installed, another innovation from BIMATEC SORALUCE. VSET is a patented, camera-based system that measures and aligns raw components before machining. Especially with large workpieces, the measurement is often a time and cost-intensive process, which may take more time than the actual machining. The highlight of VSET is that this can now also take place outside the milling machine. With the system, optical markers and measuring points are mounted and photographed on the workpiece, which also requires no experienced measurement technicians. The evaluation of the pictures by PC results in a point cloud. From this as well as from the CAD data of the component, a Best-Fit calculation as well as an stock removal control to ensure the quality of the raw part are carried out. In addition, the software generates a workpiece clamping plan with detailed rinformation in respect to the point reference which the machine automatically checks using a touch probe system before starting machining.
Aligning is greatly simplified and takes up to 70 % less time. The biggest advantage often results from the fact that errors on the raw parts can be detected and corrected before the start of machining. This includes machine downtime due to bad parts blanks as well as production losses in the late or night shift due to pending decisions about reworking the parts. Some users even use VSET for the final inspection of the unmachined part, even independently of machining.
After a two-year selection and ordering phase, the new SORALUCE FP 10000 was delivered at the end of December 2017. The final acceptance took place after thorough test operation at the end of February 2018. Since then the machine has been in production. The VSET system was purchased at the end of December 2018 and has been operational since January 2019. The following information can be found on the framag homepage: “The new travelling column milling machine makes it possible to integrate quality assurance directly into individual production steps, thereby significantly reducing throughput times. This in turn leads to an increase in output (without quality degradation) and thus to strengthening our competitive position in the highly competitive market”.
Klaus Vollrath b2dcomm.ch