Danish CS Wind Offshore Precision Milling of Offshore Wind Transition Pieces

en.Wedoany.com Reported - Danish offshore wind foundation manufacturer CS WIND Offshore has commissioned an automated milling machine, custom-built by Danish machining specialist CNC Onsite, at its Aalborg facility in Denmark, to machine high-precision cable penetrations for offshore wind farm transition pieces. The process is designed to ensure the most reliable sealing for cables powering external work lighting and platform cranes.

The new magnetic gantry milling machine developed by CNC Onsite replaces manual cutting with CNC-controlled milling, achieving sub-millimeter precision and producing clean penetrations. The six cable holes on each transition piece require precise edges to ensure a perfect seal around the power cables—a critical requirement in harsh marine environments. Additionally, CS WIND Offshore has ordered the equipment to mill 12 pressure-relief holes on each transition piece, designed to release pressure and prevent structural warping under severe sea conditions.

Flemming Smidt Pedersen, Senior Production Engineering Manager at CS WIND Offshore, explained that the initial tolerance requirement was set at one millimeter to eliminate micro-gaps and fully isolate internal electrical wiring. In an offshore environment, this watertight integrity is critical. Through a completely dust-free process, the equipment achieves an actual machining tolerance of 0.3 millimeters, surpassing the initial target, ensuring the safety of this critical infrastructure while maintaining a cleaner, more optimized manufacturing environment. The cables routed through these points not only power the platform cranes for lifting critical spare parts but also supply electricity to the identification number lighting beacons on each turbine.

The 4-axis gantry milling machine stands 2 meters high, 3.6 meters long, and 2.3 meters wide, developed at CNC Onsite's custom high-precision solutions workshop at its headquarters in Vejle, Denmark. Søren Kellenberger, CEO of CNC Onsite, stated that his team specializes in developing mobile gantry milling systems aimed at achieving consistently high-precision results on steel components. Due to the sheer size of the components, which are difficult to move to standard machine tools, the company brings the machine to the workpiece instead. This project aligns with its core expertise of delivering precision machining directly to the component.

Leveraging experience in maritime and energy projects, CNC Onsite's mobile gantry milling machine completes cable penetration machining in a single automated pass, fully replacing manual flame cutting and grinding. The equipment features a proprietary magnetic fixing mechanism that provides a stable, vibration-free base without traditional invasive clamping, using powerful electromagnets to lock directly onto the curved structure of the transition piece. This delivers high clamping force without damaging the high-grade steel surface, avoiding surface scratches and rework issues.

Since cables must pass through the structure at an angle, the penetration wall requires 45-degree angle machining, which the milling machine meets through an adjustable machining angle ranging from 28 to 90 degrees. In this project, the penetration hole dimensions are 180 mm × 350 mm. The equipment's machining range covers everything from small utility holes of 50 mm in diameter to large structural elliptical penetrations of 2,575 mm × 550 mm.

This 4.8-ton mobile machine must address significant geometric challenges at the manufacturing site: each transition piece, weighing 370 tons and measuring 7.8 meters in diameter, must be rotated on rollers to align with the cutting area. The equipment is fitted with adjustable wheeled steering mechanisms that track the cylinder's rotation, minimizing manual handling during repositioning. Kellenberger noted that the combination of advanced gantry technology and sub-millimeter precision confirms that large, complex steel structure manufacturing can meet the increasingly stringent technical standards of the global offshore energy industry.

CNC Onsite | www.cnc-onsite.dk