EMAG VLC 1200: Process integration instead of workpiece tourism – to make the manufacture of small batches of large chucked components economical

06/09/2008 - Oliver Hagenlocher

Technology integration:
turning, drilling, milling, grinding, gear hobbing – all on a single machine
The VLC 1200 is designed as a sturdy turning platform. The pick-up work spindle with direct-driven synchronous motor (no gear spindle) distinguishes itself by its high power rating (110 kW) and its torque of 11,000 Nm. The use of direct drives also allows for the integration of technologies that call for the very best control performance and synchronicity, such as grinding or gear hobbing. The integrated A-axis allows helical gearing and the B-axis angular infeed grinding. The direct driven spindle also makes it possible to generate high quality surface finishes and to hold the tightest tolerances (e.g. for precision bores) with absolute process integrity. This offers a considerable advantage over machines equipped with gear spindles that require specific mechanical compensating elements to dampen vibration. To ensure the VLC 1200 can be fully utilised in a flexible shop floor environment, EMAG offers a tool changer and magazine for up to 160 tools. The machine’s turret has been designed as a single-position tooling system that forms an integral part of the B-axis. Opposite the turning tool receptor is a milling spindle that can be equipped with Y-axis, if necessary, allowing for the use of a multitude of different tools. “Large workpieces often take conventional 6- or 8-station turrets to their limit, as their dimensions frequently present interfering edges between active and adjoining tools. EMAG offers the possibility to equip the machine with an automatic turning tool receptor, a milling spindle and a tool changer. Drills, grinding wheels, milling cutters and turning tools are automatically taken from the tool magazine and inserted into the tool holders”, explains Stefan Anders, Project Manager for the VLC 1200. Another advantage is that the tool change is a cycle time-concurrent operation. Whilst one workpiece is still being machined, the operator is free to load the magazine with the tools for the follow-on workpiece. The magazine accommodates tools of up to 60 kg in weight. Loading the heavy tools into the magazine is made easier by a tool loading fixture.

80% reduction of the throughput time
A reduction in throughput times plays an ever greater role in the machining of large workpieces. “The raw parts alone can cost a few thousand Pounds a piece. That makes it a question of some importance whether the throughput time of a batch is 170 hours or 35 hours. With the VLC 1200 and the integration of different machining technologies we are able to reduce the throughput time by up to 80%, and that releases the tied up capital much sooner”, enthuses Stefan Anders over the advantages of process integration. The throughput times for workpieces are much shorter than those achieved in classical job-shop production. For workpieces that require a number of steps to complete-machine, the reduction in waiting times is quite considerable. “When machining transmission components for bulldozers on the VLC 1200 we were able to reduce waiting times by 80%, compared to a classical job-shop production”, adds Stefan Anders. Another advantage offered by the complete-machining on a single machine is the reduction in storage space. A workpiece of 1 m diameter takes up all the space offered by a single Euro-pallet. Having to machine the workpieces on a number of different machines means that extra storage space is needed close to every one of these machines, so that the workpieces can be temporarily stored awaiting the next machining operation. This intermediate storage of workpieces often takes up twice or three times the floor space the machine itself occupies – a cost factor that is frequently ignored! The VLC 1200 reduces the floor space requirement, as technology integration means many of the components can be finish-machined in a single setup. Material logistics too are simplified. Whereas the classical job-shop production requires for the components to be transported from one machine to the next and then re-clamped each time, the VLC does everything on one machine. This also has an effect on the setting effort. No longer do 3 or 4 machines have to be set up before a component is complete-machined. No, just the one – the VLC 1200. “The smaller the batches, the more the setting effort gains in importance. There is a decisive difference between 3 machines having to be set up for the machining of 10 workpieces, or only one”, explains Stefan Anders.