February 2025

How to mill a sinking foundation to precision.

In January, Danish startup CNC Onsite was called to an urgent job at 10 MW SK Energy in Slagelse to adjust the gearbox and the newly installed generator. The gearbox was placed seven millimeters lower due to a sinking foundation. Metal-Supply reports.

The job took three days to complete and has potentially saved many months of downtime for SK Energy in Slagelse on Zealand, which had hired Siemens Energy, Ballerup to install the new generator.

CNC Onsite used its 3D laser tracker and the newly developed portal milling machine to mill optimal areas on the foundation to achieve a flatness of 0.1 mm. The connecting flanges between the gearbox and the generator now fit perfectly and are ready to produce energy for the grid.

Siemens Energy from Denmark was impressed with the result and that the tolerance is actually smaller than it was 30 years ago. The technicians approached the task with their professional skills and a good deal of creative thinking to hit the nail on the head. No two foundations are the same and you really have to work together to find the right process.

It’s important that the entire train, consisting of the gearbox and generator, is perfectly straight according to the calculated alignment, as any deviation can result in vibrations and lack of energy production.

Read the article (Danish) by Metal Supply here.