INDUCTION HARDENING is a precision process conducted entirely within the Tronex factory. A high grade, high carbon content steel is used as base material for the tool. After machining the tools are individually placed in the middle of an electrical coil carrying a very high frequency current. This current which induces a deep heat at about 900°C in the highly localized area of the cutting edges. The cutting edges are then rapidly cooled with a water or oil quench which immediately transforms this small localized area into a steel structure which is exceptionally hard. In fact the edges are so hard that they have become brittle. The tools must be tempered, by heating to around 200°C, to relieve stresses from the hardening process and to produce cutting edges which are not only hard, but hard and tough. Toughness is the ability to resist brittle fracture or sharp impact loads. The localized area of induction hardening can be seen on the backside of Tronex tools as light colored half moons or fans which surround the entire length of the cutting edges. This is not visible (although it is still there) on tools with Optimum Flush Cut edges. These tools have undergone another careful machining process to secure this ultimate in flush cutting. The process achieves very hard edges, 63 to 65 on the Rockwell C Scale, with a depth of 2 to 3 mm to allow resharpening, even multiple resharpening.