In 1986 Ansaldo Magnet Dept. (now ASG Superconductors) started, in cooperation with CERN, the design activities of the first 1 m-8 T LHC prototype dipoles. After several design steps and the manufacturing of 1+3 prototype dipoles 10 m long, the final design configuration 15 m long was defined by CERN. During the following years, a very close collaboration with CERN engineers and technicians lead to define the parameters about the most critical manufacturing processes, in particular winding of s.c. cable, collaring of coils, cold mass welding and test procedures. In the meantime, installation and commissioning of all the manufacturing plants followed: winding machines, curing presses, collaring press and welding press were installed, as well as geometrical measurements stations and vacuum chamber for leak test. Finally two manufacturing halls were fully dedicated to LHC dipoles production. At the beginning of year 2002, all the manufacturing plants were coming to be operational, ready to start the large scale production of LHC cold masses: 30 pre-series, 386 series and 30 spare cold masses have been produced till May 2007, to get a total number of 446 cold masses. In this paper we summarize all the data collected during a five years production: main manufacturing data, test results and production rate are presented. Final results about tests performed at CERN in superfluid He at 1.9 K are also included as well as correlation between test result and manufacturing rate.