Within the framework of a national funding for very large research infrastructures (TGIR), the Leprince-Ringuet laboratory for particle physics and astrophysics (LLR*) has acquired a new milling machine. With a mass of 30 tonnes, it can machine large parts (up to 2360mm x 1600mm x 500mm). It will be used to make mechanical parts of the High Granularity Calorimeter, which is intended to replace the existing calorimeter in the CMS detector at CERN’s LHC particle collider. This instrument will measure the energy, momentum and time of flight of particles produced during collisions in the LHC. These improvements are part of the HL-LHC project, which aims to increase the performance of the accelerator in order to study the Standard Model of particle physics more accurately, and perhaps find signs of new physics.