When it comes to small batch sizes it makes sense to integrate various processes on a single machine. The less often a workpiece has to be clamped before it is finish machined, the higher the precision and the smaller the chance for errors. This was the idea behind EMAG’s development of the VLC series, a sturdy platform that combines – on a single machine – the turning, drilling, milling, grinding and gear cutting of workpieces up to a diameter of 1200 mm.
All-in-One – in XXL format
21.03.2011 - Oliver Hagenlocher
A workpiece including clamping equipment, with a total weight of 3 metric tons, at the spindle nose soon makes it clear why the VLC 1200 is pretty big. It is used, for instance, for the complete-machining of planetary gear carriers and railway wheels, but also for the grinding of ceramic brake discs. The VLC Platform covers the machine sizes 500/630/800 and 1200 (= chuck diameter) and includes everything from a 2-axis to a 5-axis (pick-up) machine.
What EMAG considers „tailor-made“ becomes evident when one looks at the multitude of individual machining solutions offered. For instance, the machining area is of modular design and can be equipped with a VDI 60 turret for heavy-duty turning work and a second turret for driven drilling and milling tools. It is also possible to integrate milling spindles for the machining of spur gearings or equip the machine with disc-type turret and motor spindle with Y-/B-axis, for multi-functional machining tasks. The integrated A-axis allows for the machining of helical gearings, whilst the B-axis can be used for angular plunge-grinding operations. Where the focus is on turning work, the machine can be equipped with two turrets, opening up the possibility for 4-axis machining. The closed-loop, U-shape design of the machine base in polymer concrete MINERALIT guarantees a great chip capacity and the complete-machining of components on these multi-functional, gantry-type production centres. This concept is the precondition for short, symmetrical force distribution and thus for high static and dynamic rigidity, which lead to exceptional surface finishes and a long tool life. Constant quality, however, also calls for constant temperature. It is the reason why, on the VLC, not only the main spindle motor is cooled; the twin-circuit cooling system also keeps the main spindle bearings and quill, the turret, the electrical cabinet and the machine base at a constant temperature.
The EMAG turret is also of considerable influence in achieving a high degree of process integrity.
Fully integrated into the machine base and featuring a motor and driven tools, the EMAG turret is equipped with internally lifting Hirth coupling and a pair of bevel gears that drive the tool direct. This arrangement ensures that every turret position can accommodate driven tools.
The drive, i.e. the main spindle, is where process integrity coupled with a high chip capacity continues. A maintenance-free direct drive eliminates the need for mechanical transmission components, providing better surface finishes and greater positioning accuracy. This is of measurable benefit when compared to machines with gear-driven spindles that require mechanical compensating elements to dampen vibration. High torque rates and high power ratings make for powerful machining operations. The VLC 800, for instance, is equipped with a 76 kW motor and has a torque rating of 4,400 Nm; but different motors are also available.
To sum it all up: there are enormous savings potentials
In context with the VLC series „individual“ means that the machines can be equipped to suit a multitude of manufacturing solutions that go far beyond just metal cutting. For instance, the VLC also offers to integrate high-frequency induction hardening operations, or the press-fitting of bearing bushes, including subsequent machining operations. A practical example illustrates the potential of complete-machining: A batch size of 20 workpieces had to be turned twice, hobbed, induction hardened, drilled and ground. This was done on single-technology machines at a ratio of total machining time to throughput time = 1.5 : 170 hours. Today, these processes are combined on two multi-technology machines, where the ratio is 1.5 : 35 hours. This example also makes it clear that complete-machining reduces setup times quite considerably. Instead of having to set up three or four machines, with the VLC one setup suffices. And one should add to this that the VLC can be set up cycle time-concurrently. In other words, whilst a workpiece is being machined, the operator can already insert the tools for the next job into the magazine that accommodates tools of a maximum weight of 60 kg. Another often forgotten factor is the space taken up by the machines and the workpieces, the latter having to be stored somewhere between operations. Last, but by no means least, the material logistics also lead to cost savings. Where the classical production makes it necessary to transport the workpieces from machine to machine and involves multiple reclamping operations, the VLC does all the work on one machine.
To sum up:
The VLC series of machines offers enormous cost savings by reducing throughput times and capital outlay as well as personnel and resetting costs. Furthermore, they noticeably increase quality and precision of the components by eliminating reclamping errors and by carrying out in-process quality control functions. They are machines with which the customer can react to market fluctuations quickly and with flexibility.