Machining is enjoying a tailwind

01/10/2012 - Oliver Hagenlocher

The boom in the wind power industry shows no sign of slowing. Worldwide investment is focused on renewable energy; and wind turbines are playing an increasingly important role. One of the consequences is the increase in demand for wind turbine drive systems, an area in which ABM Greiffenberger Antriebstechnik is a specialist. The company’s focus is on the manufacture of the Azimuth drives that move the nacelle and control the blade pitch mechanism for the adjustment if the rotor movement.


The boom in the wind power industry shows no sign of slowing. Worldwide investment is focused on renewable energy; and wind turbines are playing an increasingly important role. One of the consequences is the increase in demand for wind turbine drive systems, an area in which ABM Greiffenberger Antriebstechnik is a specialist. The company’s focus is on the manufacture of the Azimuth drives that move the nacelle and control the blade pitch mechanism for the adjustment if the rotor movement.

The layman may believe the wind is responsible for the movement, but sophisticated drive technology is required to ensure optimum energy yield. The fact that wind turbines are designed to last decades means that their drive components must meet the strictest requirements for reliability and longevity.

VLC 500 MT for the machining of drive components
In an effort to increase capacity in the manufacture of their wind turbine drive systems ABM Greiffenberger Antriebstechnik invested, in 2009, in a VLC 500 MT Multifunctional Production Centre from EMAG to turn, mill and drill drive housings, planetary gear carriers and ring gears in cast iron and steel. Annual production is 6,000 components, manufactured in batches of 120 per week.

The „Do it yourself” manufacturing philosophy
For years ABM Greiffenberger Antriebstechnik has followed the strategy of manufacturing those workpieces themselves that require complex machining operations and demand a high degree of precision. As the drives are also assembled in-house, ABM has to simplify the whole component logistics as much as possible, by focusing on short journeys and continuous quality control. Reliability and longevity of the components are of the utmost importance. A single drive weighs approx. 250 kg, and repairing or exchanging it inside the wind turbine is heavy work and an expensive undertaking. To avoid it as much as possible, ABM Greiffenberger Antriebstechnik relies on the fact that the drives and their components are made to the highest quality and pass the most thorough checks. “With the components being manufactured in-house we have better control over their quality. ABM Greiffenberger Antriebstechnik manufactures high-performance drive systems that are often used for applications where safety is paramount and where quality and reliability are top priorities. To be able to inject even greater flexibility into our production we also needed to reduce component logistics to an absolute minimum”, explained Wolfgang Nickl, Team Leader “Soft Machining” at ABM Greiffenberger Antriebstechnik. Component logistics therefore played an important part in the investment in a VLC 500 MT. The objective was to eliminate the journey times between different turning and milling machines by complete-machining the workpieces on one machine. The VLC 500 MT Multifunctional Production Centre offered the right prerequisites: 1 turret with 12 turning tools, 1 milling spindle with tool changer for 32 tools, integrated automation – using the pick-up spindle – and a measuring station located outside the machining area. EMAG also supplied an automatic turnover station to accommodate machining of the second side of the component and to simplify workhandling.

The complete process from a single source
All workpieces are clamped in a special EMAG chuck that can be adjusted to accommodate any variant by simply exchanging the jaws. It was important to keep resetting times as low as possible. “We did not buy just a machine from EMAG, we bought the whole process: machine, tools, programming, clamping equipment and automation. Together, we established what the optimal process would be and then fine-tuned it to suit ABM Greiffenberger Antriebstechnik’s requirements“, adds Wolfgang Nickl. The VLC 500 MT has been integrated into an autonomous production island with a gear shaper and a washing machine. It follows that the operator is responsible for three machines, which he has to keep supplied with workpieces. This makes it necessary to provide the system with a buffer to give the operator time to attend to all his jobs without having to interrupt the production process.

The workhandling process decides whether the manufacturing solution is a success or not
The massive advantage of the VLC 500 MT lies in the fact that its automation system forms an integral part of the machine. Another advantage is the workpiece buffer with 10 storage spaces. The operator can fill the conveyor belt with raw-parts, which are then machined automatically, allowing him to attend to other jobs in the line. Wolfgang Nickl says about the automation system: “All the other manufacturing concepts we looked at required a gantry loader. For instance, a vertical boring and turning mill with the spindle below cannot function properly without a gantry loader, as it would complicate resetting and make workhandling difficult.“ As the pick-up spindle of the VLC 500 MT ensures the machine loads and unloads itself, it is not necessary to invest in additional automation components. This makes setting up easy, as resetting the machine means also resetting the automation: change the chuck jaws, change the tools, call up the NC program – and, voila, the machine is ready. To be able to reset the machine quickly, the company bought setter trolleys that were specially adapted to the workpieces, i.e. when, for instance, a ring gear needs to be set up, the operator gets the relevant trolley, which is already equipped with all the necessary tools and set-up aids. When the setup is completed and the first component comes off the machine, it is checked in the measuring chamber and series production is given the go-ahead. After that, every workpiece is quality-checked on the machine-integral measuring station of the VLC 500 MT, to guarantee 100% quality assurance. To meet their own high quality requirements ABM Greiffenberger Antriebstechnik has also worked out a tool change strategy. „We have established the service life of every tool and exchange them accordingly. No tool is used until it breaks. All tool life details are entered in the control system, which automatically reminds the operator of the need to change the tool. This has allowed us to reduce our reject rates to an absolute minimum.”

Partnership – with the focus on cooperation
Before ABM Greiffenberger Antriebstechnik invested in the VLC 500 MT the company used only horizontal turning machines. Now, for the first time, the components are being complete-machined vertically, using different technologies. „Our staff faced a learning process. We sent them to EMAG for two weeks training. Home again, they were able to operate the machines and set up new components. Of course, it called for adjustments to be made, but our staff quickly got used to the changes and soon began to notice the advantages offered by vertical machines. For instance: the chips fall into the conveyor without hindrance. The problems we had in the past with snarled chips have been eliminated completely”, assured us Wolfgang Nickl. During the first production phase the ABM Greiffenberger Antriebstechnik -Team was supported by an EMAG specialist during two weeks of handholding. He answered questions and looked over their shoulders during setting up and operation of the machine.  “This gave our staff a true feeling of security; and two weeks later the first workpiece was coming off the machine without help”, summarised Wolfgang Nickl  the cooperation received.

ABM Greiffenberger Antriebstechnik GmbH
ABM Greiffenberger Antriebstechnik develops and produces innovative drive system solutions of the highest quality. Electric motor and transmission system come from a single source and are already coordinated with great precision at the development stage. The results are custom-made solutions for the manufacturers of, for instance, industrial trucks, lifting equipment, biomass heating systems, wind energy plants and textile machinery. In its three locations in Marktredwitz and Plauen the company employs over 630 staff and produces on average 300,000 drive units per year. Six subsidiaries in Europe, North America and Asia - and agencies in the most important industrial countries of the world – guarantee that close contact is maintained with customers across the globe.

Contact

Oliver Hagenlocher

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