Cutting tools for CNC machining industry:

Cutting tools for drilling, milling or cutting materials are high-tech products with an industry behind that tries to optimize the durability of these tools. Besides abrasion such tools can loose their coating during operation or they can break spontaneously. The following 3D topography scan was made at the knife edge of a cutting tool for a CNC milling machine:

One Linescan would only show a nice smooth line, the knife edge seems to be fine. But the 3D topograpy image proves, that line by line a notch gets visible that causes a spontaneous breakage of this knife when it would be used. A standard profilometer measurement delivers the wrong result.