Making light work of heavy-duty machining

02/17/2012 - Oliver Hagenlocher

The larger the component, the smaller the batch size – this is the way one could describe the demands made on heavy-duty machining in many branches of the industry. In fact, this simple equation provides as much of a challenge to wind turbine engineering and the production of large commercial vehicles as it does to, for instance, the railway construction industry. Many of the very large components are not only produced in small batches, the relevant market participants are also expected to produce them at the highest quality. Existing multi-stage, unnecessarily complex production processes do, however, not work in favour of these demands, as every re-clamping of the workpiece represents an inherent danger to process integrity and component quality. The multi-functional VLC production centres from EMAG follow a totally different and more efficient approach in heavy-duty machining. Workpieces of up to 1,200 mm diameter and a weight of 1,500 kg are machined vertically, in a single setup, and on one machine that accommodates a number of different machining processes and includes automation.


The larger the component, the smaller the batch size – this is the way one could describe the demands made on heavy-duty machining in many branches of the industry. In fact, this simple equation provides as much of a challenge to wind turbine engineering and the production of large commercial vehicles as it does to, for instance, the railway construction industry. Many of the very large components are not only produced in small batches, the relevant market participants are also expected to produce them at the highest quality. Existing multi-stage, unnecessarily complex production processes do, however, not work in favour of these demands, as every re-clamping of the workpiece represents an inherent danger to process integrity and component quality. The multi-functional VLC production centres from EMAG follow a totally different and more efficient approach in heavy-duty machining. Workpieces of up to 1,200 mm diameter and a weight of 1,500 kg are machined vertically, in a single setup, and on one machine that accommodates a number of different machining processes and includes automation.

Heavy-duty machining is booming. Responsible for this are the big success of wind turbine construction in China and Europe and the ever increasing output of commercial vehicles in almost all relevant markets, from South America to Asia. According to the foreign trade experts at Germany Trade and Invest (GTI) Brazil’s production in HGVs rose by over 12 percent during the first half of 2011 compared to the same period the previous year. In China, the production of HGVs tripled in 2009/2010. The railway construction industry of some countries also has a great chance of considerable growth. For instance, the GTI estimates that Russia will be investing over 85 billion Euro in its railway system before the country is going to host the football world championships in 2018.
What do these branches of the industry have in common when viewed in the context of heavy-duty machining requirements? Whether we are talking planetary gear carriers for wind turbines, brake discs for commercial vehicles, or railway wheels, the demands made on the different production planners are very similar. Component quality must pass the severest tests, as all these parts will be exposed to extreme stresses when in service. Take a wind turbine, for example: it is in service for an average of 120,000 hours and exposed to inconsistent wind conditions for 20 years and longer. But its production must be highly flexible, despite relatively small numbers; and the production tools used ought to be adaptable for the machining of other components, without involving complex conversion work.

Machining workpieces of up to 1.5 metric tons in weight

Meeting the requirements of heavy-duty machining with the help of a compact production system concept is no matter of course. Many companies use complex, interlinked, multi-stage processes to machine large workpieces. The VLC production centres from EMAG, however, rely on a totally different approach. Not only do the machines load themselves – with the help of a pick-up spindle – but the machining area accommodates all necessary machining processes – turning, drilling, milling, grinding, gear hobbing – on the same machine, and in a single setup. To achieve this, the production centre is equipped with automatic turning tool receptor, milling spindle and tool changer. The single setup ensures a high degree of dimensional accuracy and a constantly maintained, excellent surface finish.

The advantages of vertical machining
At the top of EMAG’s range of heavy-duty machining centres is the VLC 1200, presently the world’s largest pick-up machine. It handles workpieces of up to 1,200 mm diameter and 1,500 kg in weight. “Despite having to handle these enormous components, the production centre displays the same qualities as all the vertical pick-up machines from EMAG”, explains Markus Woitsch, Business Unit Manager Application Engineering. To be able to explain the success the VLC machines are enjoying in heavy-duty machining circles it is important to have a closer look at the basic construction of this machine series. The spindle carrying the workpiece is positioned vertically above the tool, which allows the chips to fall unhindered into a conveyor located below, from where they are transported out of the machining area. This prevents the hot chips from heating up the workpieces and contaminating the workspindle. “This is a great advantage especially in a lightly-manned, fully automated, heavy-duty machining environment”, confirms Markus Woitsch. Another success factor of this kind of heavy-duty machining is the quality control. Sourcing of the raw-parts is where the heavy investment starts; and mistakes during the production process would result in particularly high, totally unnecessary costs. The answer of the designers of the VLC series to this challenge has been a highly sophisticated one: a probe with an accuracy of 2 micron measures and checks the workpieces in-between machining operations.

Impressive application examples

Some of the advantages of the VLC as used in various branches of the industry are explained by the following two application examples:

  • One manufacturer uses an EMAG VLC 500 in the production of components for the nacelle of a wind turbine. Batch sizes are approximately 120 per week. Production of the six different components calls for up to 12 different tools. “These numbers already show the flexibility of the machine. Without time-consuming modifications, the VLC 500 is capable of machining a number of totally different constituent components”, emphasises Markus Woitsch. “Furthermore, the wind turbine specification calls for a particularly high degree of component quality, which we can guarantee with the VLC.”
  • An EMAG VLC 1200 that complete-machines railway wheels and brake discs has to carry a weight of three metric tons – including the chuck – at the spindle nose. The production centre also incorporates a chain magazine for 36 tools. High feed rates in the X- and Z-axes of the work spindle and a maximum torque of 13,000 Nm make for short throughput times. “This enormous amount of power, the integral pick-up automation and the intelligent combination of diverse machining applications in a single setup have enabled us to reduce throughput times by up to 80 percent, compared to previously used processes”, confirms Markus Woitsch.


A minimal setting effort and a high degree of process control
The advantages of a multi-function concept have a positive effect also on the production of components for construction machinery, HGVs and agricultural machines. Compared to the classical shop floor production of such components on three or four machines, the work load is greatly reduced when one has only the VLC to set up. “It makes a great difference whether I have to set up three or four machines for the production of 10 components, or just one”, explains Markus Woitsch.

The decisive factor in the success of the VLC series – over a hundred of these machines are already being used worldwide – is their modular design. Every machine is being configured to suit the user’s particular production requirements. The possibilities are many: one or two turrets, the integration of grinding and hard machining processes and the different workpiece capacities of the VLC 500, VLC 800 and VLC 1200. EMAG offers the most comprehensive range of vertical turning machines with integrated workpiece handling, measuring and multi-functional machining units.

Contact

Oliver Hagenlocher

Press and publishers

Phone:+49 7162 17-267
Fax:+49 7162 17-199
E-Mail:communications@emag.com

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