The Carbide Head
The Carbide Head is either extruded in sticks or preformed from a specific manufacturer to a designated size usually .020” – .030” larger than the finished diameter. Carbide selection is very critical for materials that are abrasive and require different carbide composition than exotic types of materials. The proper combination of cobalt content and grain size make noticeable differences while machining. The carbide is then precision ground to size allowing for predetermined backtaper, relief depths, and contours. Coatings are applied to obtain ID surface finishes as low as 10Ra, depending on the material being drilled. There are also conditions such as water soluble coolants which occasionally do not have the lubricity necessary to allow the tool to cut freely therefore, coatings are the alternative.