Shape raked / THREADING General dimensions Type of Taps leading shapes Destalonados rosca Taper U in % diameter Distribution over the chip thickness profile per tooth The limitation in the length of the taper on taps for blind holes obeys the usual demand in blind holes for the minimisation of the incomplete thread area (not useful) due to the taper geometry. Chip thickness+shape detail Surface finish with steam treating (Urdin) This detail explains the inevitable difference in performance in favour of the Form B or through tap, whose taper length is clearly greater (+ 80% approximately with respect to the type for blind holes). This is a surface heat treatment that creates a layer of Fe3O4 ferrous oxide with a sub-micron thickness and whose distinctive visual appearance is its characteristic black-blue. It is carried out in specifically prepared atmosphere chamber ovens, which are totally innocuous from the health and environmental point of view. The process basically consists of a thermal treatment cycle structured in stages with different increases on the time-temperature binomial and supplied with steam during a specific phase. Within the hole shape short In view of that discussed, the importance of the taper is obvious and its quality demands are at maximum levels. / 43