The situation
A 10 MW power plant in Denmark was replacing its generator. During installation of the new unit, Siemens Energy's technicians found that the gearbox and generator would not align. The cause was a foundation that had been sinking gradually, leaving the gearbox roughly 7 mm lower than the generator.
Alignment between gearbox and generator has to be exact. Even small deviations cause vibration, wear components faster, cut efficiency and can end in costly downtime. And the offset could not be seen, so it took precise measurement to find and fix.
What we did
CNC Onsite was called in as an urgent job in January 2025. The first step was a complete 3D laser scan of the foundation. The measurements confirmed the misalignment and showed which areas of the foundation needed correcting; Siemens Energy's specialists in Germany then selected the areas to mill.
The machining was done with CNC Onsite's newly developed gantry milling machine, brought into the plant and set up over the foundation. Technicians milled four selected areas directly on site to a flatness of 0.1 mm, restoring the correct position of gearbox and generator without rebuilding the foundation.
The result
After machining, the connecting flanges between gearbox and generator were restored and realigned, and the plant could resume operation. The whole job took three days.
- Gearbox and generator alignment fully restored
- Foundation machined to 0.1 mm flatness
- Misalignment of about 7 mm corrected
- Completed in three days, potentially saving months of downtime
- Power generation back on the grid
What it means for ageing plants
As power plants and industrial drivetrains age, foundation settlement can create alignment problems that threaten reliability and push up maintenance costs. Precise measurement combined with on-site machining can restore alignment without major civil works: less downtime, avoiding costly component replacements, and a longer service life for existing assets.
