/ THREADING generic framework, the specific detailed data depends on each manufacturer which allows relatively different properties to be obtained. Obviously the temperature cannot exceed, under any circumstances, the tempering threshold (550°). Apart from the familiar cosmetic effect, it provides a significant technical contribution that benefits the tool: - The thermal factor provides a reduction/elimination of residual stress arising from the manufacturing process which contributes to increasing the life of the tool (totally stress free grinding is impossible in practice). - The same factor sharpens the cutting edges by weakening (burning action) the micro-burrs associated with the plastic micro-deformation of wheel grinding. This contributes to the life and surface quality of the threads (grinding that is totally free of plastic deformation is impossible in practice). - The oxidation causes micro-cratering to the surface and as a consequence the creation of numerous micro-deposits of lubrication fluid, which contribute to reducing/elimination of deterioration by adhesion (cutting edges added to by cold welding of the worked material, a frequent problem with ferrous materials, particularly low alloy). 1) The rationale of this family of taps is its versatility in terms of efficient response to the tapping of different materials, overcoming the traditional technical barriers imposed by models with a single material specialisation and the consequences derived from that. 2) It is the result of a development based a thorough study and analysis of the real problems in tapping, through long and extensive experience as a manufacturer. The development is completed with the application of the corresponding "know how" in the wide and complex series of innovative redesigns necessary for the product and process. 44 / 3) The efficiency guarantees are backed up by numerous experimental results both internally (tapping tests in our R&D test laboratory) and externally on-site. 4) Without disputing its proven all material effectiveness as its main purpose, the taps show especially noteworthy capabilities on mechanical construction and stainless steels./ Conclusions on the multi-metal tap