CNC Onsite’s new gantry milling machine levels the foundation

VEJLE, Denmark, 10 February, 2025 – This month, CNC Onsite, a Danish precision machining expert, was called on an urgent job at a 10 MW power plant in Denmark to re-align the gearbox and the new generator. Caused by a sinking foundation, the gearbox was positioned seven millimeter lower. The job took three days to complete, potentially saving many months of downtime for the power plant, SK Energy located in Slagelse, Denmark, who had contracted Siemens Energy, Denrmark, to set up the new replacement generator.

Armed with its 3D laser-scanner, and the newly-developed gantry precision machine as well as problem-solving skills, the technicians from CNC Onsite were able to mill selected areas on the foundation, achieving a 0.1 mm flatness. The connecting flanges between the gearbox and the generator fit perfectly and will shortly produce energy for the grid.

”We were impressed with this result and that the tolerance is actually lower than it was when we first installed the power plant 30 years ago. The technicians went about the problem using their technical skills and a fair amount of creative thinking to hit the nail on the head. No foundations are the same and you really need to work together to identify the right process. My colleagues in Germany who selected the areas to mill were equally impressed,” says Peter Bang, Service Manager, from Siemens Energy.

It is important that the complete train consisting of a gearbox and generator are completely aligned according to the calculated alignment as any deviation can result in vibrations and failure to generate energy.

Thousands of consumers and several industries in mid-Denmark depend on the electricity and heating from this power plant.
The cause of the problem: The foundation for the gearbox and generator was sinking, resulting in a significant misalignment.

The 30-year-old generator was replaced with a new generator and when this was installed, Siemens Energy technicians believed that the generator was positioned higher than the gearbox, a scenario the naked eye cannot observe. This suspicion confirmed by the 3D laser trackers, which CNC Onsite used to measure all areas.

“3D laser scanner is a prerequisite for this type of job. There is never just one model answer to realignment. Each job is different. The 3D laser allows us to create in 3D the whole physical structure and pinpoint exactly the ideal area to mill,” says Hans Løvlund Toft, technical director, CNC Onsite.

The challenge was to select the areas that could be milled reliably to create a completely flat surface. After analysing the 3D drawing, including the feet of the foundation, Siemens Energy technicians in both Denmark and Germany correctly selected the steel inserts in the foundation as they were pultruding above the floor.

Launched on the market only last year, CNC Onsite’s gantry milling machine was the perfect tool for the job as it is able mill to precision and achieve well below 0.05 mm precision. Four area on the foundation were milled, levelling the foundation to fit align the new generator with the gearbox.

The quick turnaround for this job is believed to have saved many thousand Euros both in loss of output and many weeks of downtime. Thanks to CNC Onsite custom-built gantry milling machine the job, the foundation level was restored.
Over time and years of long operation with vibrations and forces on the steam turbine concrete foundation, sinking foundation is not an unusual phenomenon.

CNC Onsite developed the gantry milling machine in response to customer demand, particularly in the wind industry for fine tolerances. Side plates of support structures, metal presses for heat exchangers, wind turbine foundations and worn surfaces on an older large hydraulic press are typical jobs CNC Onsite has already conducted in Denmark and Sweden. Germany is a destination on the horizon in the not too distant future.

About CNC Onsite
Headquartered in Vejle in Denmark, CNC Onsite designs, builds and delivers high precision mobile machining for wind turbines including offshore foundations. The machines can be built to perform a range of tasks. CNC Onsite serves the onshore and offshore wind energy sector delivering as standard solutions: machining of large diameter steel flanges and blade root ends; specialized repair services covering yaw ring, inserts in blade root, rotor lock, generator shaft, bearing housing and threaded holes. Removal and replacement of worn and broken bolts round off the offering.

www.cnconsite.dk

Media contact for CNC Onsite:

Dr. Malene Conlong
Moller International (for CNC Onsite)
Tel: +49 171 699 2650
Email: M.conlong@mollerint.dk