View various clippings of articles written by Pulse for different magazines
Wind turbine power is rapidly emerging as a leading technology of choice. Wind power is currently expanding on a global scale of 20% year on year and this is set to continue beyond 2012 at which point the global wind turbine market will be worth a staggering US$300billion.
The manufacturing and technology development for this emerging market is based in Denmark. In the Jutland region of Denmark alone, five of the world’s largest wind turbine manufacturers have manufacturing plants. Home to the likes of Vestas (24% Global market share), Siemens (8% share) and GE Power to name a few, the region is a hotbed of activity for the industry.
The industry also employs thousands of people at subcontract manufacturing facilities that support the main OEMs. One such subcontract manufacturer that supplies companies such as Vestas Wind Systems, GE Wind Energy, Nordex Energy and Repower Systems is Ertech Stal A/S of Hedensted. Ertech Stal produces hubs, base frames, rotor locks and bearing housings for the wind industry as well as ship propellers, thrust pads, mould tools and hydraulic press frames for world renowned companies. However, 80% of the company’s business focuses upon the growing wind turbine market and it is here that the support of TaeguTec cutting tools has proven invaluable.
Established in 2000 with six employees and one bed mill, Ertech has rapidly expanded to a company with 180 employees and 16 machine tools and this growth was recognised in 2005 with the company winning the ‘Gazelle Vinder 2005 Vejle’ regional fast growth award.
The mainstay of the business is based around the production of hubs for the wind industry with Ertech producing 30 hubs and frames each month. The hubs vary in size with the smaller 10 tonne hub delivering a power output of 2MW, whilst the larger 56 tonne hub sits upon a turbine that produces 5MW of power. The machining time varies from 10 to 20 hours per hub and this primarily involves machining the skin off the cast and drilling holes. Swarf removal ranges from one to 10 tonnes per hub, a metal removal rate unavoidable due to the sand casting process of the cast iron parts.
As Ertech Stal A/S Technical Manager, Mr Kenneth Volker comments: “Because our parts are sand casted we have to machine to a depth of between 20 and 40mm to remove the skin of the cast. To accommodate such heavy duty machining we have very large FPT bed mills with working envelopes ranging from 3 to 5.5m high and 8 to 30m in length with a capacity to hold over 100 tonne castings. However, we also need rigid, robust and extremely productive tooling and TaeguTec has supported us with this.”
TaeguTec now supplies Ertech Stal with over 35% of its cutting tools with TaeguTec’s Face Mills, T-Drill and the Set-Mill Series proving extremely productive and successful. As a renowned supplier to the Danish wind turbine industry, TaeguTec started its relationship with Ertech Stal in 2001 and it has continually strived to share its expertise with Ertech to promote highly productive and cost effective machining.
With the majority of machining demanding large removal rates on large surface areas, TaeguTec’s APKT inserts were initially introduced and these were followed by TaeguTec’s wiper inserts which immediately gave improved tool life, enhanced chip removal and higher feed rates.
The introduction of TaeguTec Face-Mills made a considerable impact on facing and interpolation operations. Cutting on the periphery of a large bore, a competitor Face Mill was making 9mm deep cuts that took 19 passes to complete the operation. With technical support from TaeguTec Korea, a Face Mill was developed with 60 inserts and it made immediate improvements. Taking 14mm deep cuts, the TaeguTec Face Mill managed to complete the process in 12 passes as opposed to 19. With each pass taking 20 minutes, this one tooling change saved Ertech Stal two hours and 20 minutes per hub, saving Ertech 70 hours of machining per month. The Ertech machine used for this process is a powerful and rigid machine with a 37KW spindle that comfortably accommodates deep cuts and high feeds.
The relationship between Ertech and TaeguTec has blossomed as Mr Volker continues: “There is a fast line of communication between us and TaeguTec. We frequently need new and special tools developed and our local TaeguTec representative will work to tirelessly and rapidly to resolve and support us with any tooling issues. Tooling can be developed in Korea and sent to us rapidly and this fast working chain now sees us use TaeguTec for all our Face Milling operations.”
“One particular cutter has been developed to conduct the back cutting of holes. The specially designed tool produces flats on the back side of the hub base frames for us to check parallelism of the workpiece. It allows us to check parallelism without having to turn the base frames around, something that would take at least an hour to re-set the base.”
A major process of hub production is the drilling of holes with 300 and 200 holes in the large and small hubs respectively. For this process the TaeguTec T-Drill has come to the fore at Ertech Stal. The smaller 2MW hub requires 54 holes on each of its three faces plus an additional 50 holes on the base (212 holes). Previously using a competitor drill for the 39mm diameter and 160mm deep holes, Ertech drilled at a 110m/min cutting speed with a 1000mm/min feed. However, the pointed drill was incapable of cutting to depth and had to drill 171mm deep due to the pointed end of the drill. The solid carbide drill machined 270 holes before needing to be replaced, a changeover process that added to the cycle time.
TaeguTec introduced its three insert T-Drill to the process and immediately made improvements. Running at 290m/min with a feed rate of 1100mm/min, a 10% productivity improvement was realised. Utilising the SPMG TT6030 insert the tool life was significantly improved and the cost was drastically reduced. The T-Drill produced 200 holes on each face of the four sided insert resulting in a total of 800 holes for the three inserts as opposed to the 270 previously achieved.
The T-Drill eliminated drill changeovers to further reduce the production cycle time. TaeguTec Denmark representative for Ertech, Mr Henrik Spangholt says: “The new T-Drill has saved production cycle times by 10% and there are no changeovers. On this one job the square end of the T-Drill now means that Ertech machine the equivalent of 1kilometer less per year. Added to this is the reduced cost and improved tool life of the inserts in comparison to the solid carbide drill. The benefits have been considerable.”
Looking to the future Mr Volker concludes: “We have a very close working relationship with TaeguTec and they continually strive to improve upon the benefits of their own tools as well as the competition. With this attitude we know that we have a partnership that will grow further in the future.”
