Over the past few months, additional capacity and expertise have been built up for demanding milling and turning applications on the MT 715 – both in sales and in application engineering. »The aim is to demonstrate to customers, in an even more targeted manner, the potential of the machining centers and the advantages of complete machining on a single machine, and to work together to develop suitable machining and turnkey solutions for complex applications,« says Axel Boi, Vice President Sales Aerospace.

Full 5-axis machining, milling and turning in any sequence on six sides. Complementary, integrated technologies – gear hobbing, gear shaving, gear shaping, impact tooth milling and polygon turning: The MT 715, for workpieces up to 400 mm in diameter and 1,000 mm – or, with an extended working area, 1,400 mm – in length, combines various manufacturing steps and technologies on a single machine platform. Processes that were previously spread across several machines can now be carried out as a single, continuous manufacturing process – offering benefits in terms of precision, flexibility, set-up time, cycle times and process reliability.

The integrated workpiece automation and high tool capacities enable complex machining operations for sectors such as medical technology, tool manufacturing, mechanical engineering and aerospace.

Equipped with two machining units, the MT 715 two and MT 715 two⁺ variants further expand the range of applications. In addition to the milling spindle for supplementary machining operations, a turret with up to twelve tool positions is available, which can be supplemented with a faceplate for the production of shaft components.

When extreme process forces are at work

Machining high-strength and tough materials – for applications in the aerospace sector, for example – in a reliable manner presents a particular challenge. These materials are extremely resilient yet difficult to machine. Extreme process forces are at play; chips break with difficulty and can lead to machine stoppages. Furthermore, long machining times place a strain on the machine, tools and clamping devices alike.

The MT 715 machining centers are also designed to handle such challenging processes involving machining ‘from solid’, with high material removal rates and long cycle times for complex components. Milling and turning operations can be optimally combined to suit the process – ensuring short chips and uninterrupted machining. The machine’s design creates the conditions for high precision, high performance and stable processes.

Fully implementing complex requirements – in a single process

A recent aerospace project by the CHIRON Group, involving an MT 715 two⁺, demonstrates just how demanding such machining operations are in practice. The project involves machining a component for a defence application from the heat-resistant superalloy MARVAL X12H. A cylinder weighing around 50 kg is being machined into a complex five-part component weighing approximately 3 kg, with a correspondingly high chip volume.

The requirement: for safety reasons, the component must be machined entirely from a single workpiece. At the same time, the thin wall thickness of 1.5 mm places high demands on process control and precision. Additional clamping operations or transfer to further machines would significantly increase the risk of warping or damage. Furthermore, production would be too time-consuming and labour-intensive, and would not be ideal from an economic perspective either.

In addition, a component is being manufactured on the MT 715 two⁺ using a pure turning process: a long sleeve made from 300M steel. As the sleeves vary in length, the customer is using the machine variant with an extended working area of X 1,550 mm. This will enable new components to be integrated into production on the MT 715 two⁺ in future.

The key advantage is that both components can be machined in their entirety without interruption, from the feeding of the blank to the removal of the finished components.

Turnkey expertise for complex processes

However, selecting the right milling and turning center with ample power reserves and the necessary flexibility is only part of the solution. Particularly when dealing with demanding materials and complex components, the machining strategy, tools, clamping technology and process parameters must be precisely coordinated. Only then can high-strength components with an extremely high chip volume be manufactured reliably and cost-effectively.

This is where the turnkey expertise of the CHIRON Group comes into play. For the defence component – the ring plus mounting bracket – Patrick Mink’s team developed the following machining strategy: first, a central bore with a diameter of 80 mm is pre-drilled and then machined from the inside out to achieve the final geometry. To produce short chips, targeted turning-milling operations are used – milling is carried out whilst the workpiece is rotating.

Machining is carried out using a high-performance spindle designed for demanding aerospace applications. »High theoretical torques sound impressive at first. However, it is far more important to be able to fully utilise this cutting capacity under real machining conditions,« explains Matthias Efinger, Head of Machine Development 2. »To achieve this, the feed rate must be significantly increased so that the material breaks in a controlled manner. This is precisely why a machining center such as the MT 715, with its high rigidity and stability reserve, is required.«

Tool testing, tool selection, CNC programming and the design of the machining process are also part of the solution. The same applies to clamping technology: the final machining of the milled part is carried out not by the counter-spindle, but by the turret. This allows different clamping devices to be integrated flexibly and even complex geometries to be machined with stability. The clamping pin, which was manufactured earlier, serves here as a stable mounting point, enabling the component to be fully finished.

The aerospace project serves as a prime example of the advantages offered by the MT 715 when machining demanding materials: powerful machining even of large volumes, stable processes and the ability to flexibly machine a wide range of parts from start to finish on a single platform.