A process for making spare parts for refiners used for producing paper, in particular for making refiners for preparing paper pulps, where the pulp enters at one end and exits on the other side, passing through a rotary body or rotor or male component equipped with bars (or grooves) and a casing or stator or female component bearing fixed counter-bars. This process includes mechanical machining of unmachined sectors; routing or mechanical machining of the machined sectors to obtain a set of bars or grooves or holes; putting together the cone (rotor or stator by joining all of the sectors to the supporting flanges; mechanical machining (turning and grinding) to finish the cone; and balancing of the rotor or stator.