During industrial forging of big hot metallic shells, it is necessary to regularly measure the dimensions of the parts,
especially the inner and outer diameters and the thickness of the walls, in order to decide when to stop the forging
process. The inner and outer diameters of the shells range from 4 to 6 meters and to measure them a large ruler is placed
horizontally at the end of the shell. Two blacksmiths standing on each side of the ruler at about ten meters from it
visually reads the graduations on the ruler in order to determine the inner and outer diameters from which the thickness
of the wall is determined. This operation is carried out several times during a forging process and it is very risky for the
blacksmiths due to the high temperature of the shell when the measurement is done. Also, it is error prone and the result
is rather inaccurate. In order to improve the working conditions, for the safety of the blacksmiths, and for a faster and
more accurate measurement, a system based on two commercially available Time Of Flight (TOF) laser scanners for the
measurement of cylindrical shell diameters during the forging process has been developed. The advantages of using laser
scanners are that they can be placed very far from the hot shell, more than 15 meters, while at the same time giving an
accurate point cloud from which 3D views of the shell can be reconstructed and diameter measurements done.
Moreover, better dimensional measurement accuracy is achieved in less time with the laser system than with the
conventional method using a large ruler. The system has been successfully used to measure the diameter of cold and hot
cylindrical metallic shells.