Flange facing gets simpler and faster.
When it comes to portable flange-facing machines, Acteon company Mirage has few serious rivals. Part of the reason for this is the constant striving by the company to respond to the needs of its customers, which, as Mirage managing director Richard Silk explains, centre on speed and simplicity.
“Whether our flange-facing machines are being used in a maintenance or a production setting, there is invariably pressure to get the work done as quickly as possible. On top of that, there is a huge demand for machines that can be easily operated by less highly trained individuals.”
Mirage rents or sells a variety of flange-facing machines capable of dealing with flanges from just a few centimetres wide to those up to 8 m in diameter. A common feature is the ease with which they can be set up. The machines are generally designed with independent bases that have axially adjustable feet. This enables the machines to be positioned against the flange to be faced within 0.25–0.5 mm very quickly and without too much skill.
Another common feature of the machines is the gearbox, which is preset to produce a variety of common surface finishes; this too saves time when preparing a machine for use.
For users that are happy simply to produce a flat finish on the flange (with no defined machine profile), machines can be supplied with milling heads rather than single-point cutters. These reduce the actual machining time dramatically and have found great favour in the rapidly expanding wind turbine manufacturing sector.
“The makers of wind turbines are under immense pressure to increase productivity,” says Silk. “Their order books are filling rapidly as more and more wind farm developments get the go-ahead in many countries around the world. Flange facing is a significant part of the manufacturing process: the composite blades are each finished with a part-steel flange to connect them to the turbine generator, which itself sits on a steel flange on top of the tower. Getting the tower flange very flat is particularly important, as this has been found to heavily influence the life of the bearings in the turbine. Here, we are seeking to achieve 0.1-mm flatness around a flange that can easily be 2–3 m in diameter.”
Silk points out that the size of modern wind turbines makes it impractical to take the blades or the towers to a fixed flange-facing machine and that a portable machine is the only option for preparing the flanges. Since 2000, Vestas, probably the world’s best-known wind turbine supplier, has faced roughly 10,500 blades using one of six Mirage machines that they own. During that period, the machines have proved to be reliable and their maintenance requirements have been minimal.
More importantly, over that period, the flange-facing process has been speeded up considerably. Initially, the company was facing two blades a day. It is now treating one blade every 30 minutes. Setting up the machines is much simpler than it used to be, and the milling head reduces the cutting time compared with a single-point cutter by roughly 80%.
“Wind turbine manufacturing is a fascinating business,” says Silk. “It has moved forward very quickly over the last few years and has stimulated a great deal of development on our side. The flange-facing machines that we are supplying now are very much more advanced than those of a few years ago. I feel that we can be proud of the contribution we are making to this important, emerging industry.”