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+86 186 5928 0806

Metal Fabrication and Machining for Wind Tower Manufacture

The tower of the wind turbine carries the nacelle and the rotor.
Towers for large wind turbines may be tubular steel towers, lattice towers, or concrete towers. Most modern large wind turbines are delivered with tubular steel towers, manufactured in sections of 20-30 meters with flanges at either end, and bolted together on the site. The towers are conical (i.e. with their diameter increasing towards the base) in order to increase their strength and to save materials at the same time.

wind towers

Openex is your complete machining and steel fabrication solution — a one-stop shop — for critical wind turbine parts, such as wind towers, large housings, torque arms, flanges, and more. And we help you seamlessly navigate the entire process from CNC machining and welding to painting and coating.

Components we've manufactured for wind energy:
Rotor hub
Large housing
Torque arms
Wind towers
Other metal structures.

Contact us at or call us at +86 186 5928 0806 for more information about fabrication or machining for wind turbines and to receive a free project quote today.

How was the wind tower manufactured?

Rolling Conical Tower Sections

This image from a tower manufacturer's workshop shows how a steel plate is rolled into a conical subsection for a wind turbine tower. It is a bit tricky to achieve the conical shape, since the tension (pressure) of the steel rollers has to be different at the two sides in order to make the plate bend properly.

plate rolling for wind tower
Towers are assembled from these smaller, conical subsections which are cut and rolled into the right shape, and then welded together.
Towers are usually manufactured in 20 to 30 m sections (65 to 100 ft.), the limiting factor being transportation on roads or rail. Typical modern tower weights are 40 metric tonnes for a 50 m (165 ft.) tower for a turbine with a 44 m rotor diameter (600 kW), and 80 metric tonnes for a 60-meter tower with a 72 m rotor diameter (2000 kW).

Towers for wind turbines are generally designed by each turbine manufacturer since the entire wind turbine has to be type approved as a unit.  So even if some towers are manufactured by independent producers, they are always specific for each manufacturer. Independent tower manufacturers are often also manufacturers of oil tanks or pressure vessels since the machinery and safety inspection procedures are very similar.

In order to end up with a cone-shaped section, the plate used for rolling has to be curved along the longest edges, and the short edges are not parallel. Most tower manufacturers use programmable laser cutting tools in order to obtain the appropriate shape for the steel plate.

Steel Sections are Powder Welded

Each tower section is welded with a seam lengthwise, plus a circular welding seam to connect to the next section of the tower. This is done by placing the tower sections on a rolling bed which slowly rotates the tower, while an operator with a powder welding machine welds the sections from the outside and another operator welds a corresponding set of seams on the inside.

Checking Welding Seams for Safety

Welding seams in towers are checked using ultrasonic or x-ray devices. Important seams are checked 100%, while other seams are checked on a sample basis.

Installing and Assembling Wind Turbine Towers

Attaching Towers to their Foundations
Towers are usually bolted onto the concrete foundations on which they are placed.
There are other methods, the tower is cast into the concrete foundation, and where the lowest section of the tower is subsequently welded together directly on the site.
This method requires that the tower be fitted with special guides and clamps to hold the two tower sections in place while the welding is being done. It also requires a small mobile tower factory including a generator, welding gear, and x-ray inspection equipment for checking the welding seams.

Wind turbine tower sections are bolted together using hot-rolled steel flanges, which are welded to the end of each tower section.

Bolt Assembly
The tower sections are bolted together inside the tower. The quality of the flanges and the bolt tensions are important parameters for the safety of wind turbine towers.


About Openex

Openex is home to a full-service, one-stop-shop, contract manufacturing company producing custom large machined parts and fabrications. Our full large fabrication services including large machining, cutting, welding, rolling, punching, braking, testing, painting, and others.
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