1. Main difference of end mills made of good tungsten carbide and common tungsten carbide (different material and the same manufacturing process)They have similar performance on hardness, toughness and the difference is on the wear resistance, which mostly decides the life of the end mill.End mills made of common tungsten carbide only apply for cast iron, carbon steel, low alloy steel, copper alloy. These materials have low tensile strength (under 1000Mpa) and low hardness (under 30HRC). For stainless steel, high alloy steel, prehardended steel, hardened steel (high hardness or high tensile strength),  these end mills have inferior performance and even can't work on these materials. Usually the life of end mills made of tungsten carbide is about 30% shorter than that of end mills made of good tungsten carbide when milling  low tensile strengh materials or low harden materials.2. Main difference of end mills made of CNC machine and common machine (the same tungsten carbide)They have the same performance on hardness, toughness and wear resistance and the difference is on the tolerance.Usually we have 3 types of tolerances on end mills, tolerance of shank and diameter, tolerance of flute and tolerance of cutting edge. They have the same tolerance of shank and cutting diameter. The main difference is on the tolerance of flute and the tolerance of cutting edge.  For milling metals, the most importance is to make sure that the cutting edges of end mill can touch the work-piece at the same time, which need smaller tolerance of end mill. And, we can control the tolerance of cutting edge in 1S (0.01mm) by CNC machine. The common machine  can control the tolerance of cutting edge in about 5S (0.05mm) if the workers are on good status. So, when milling metals, the end mills made by common machine shall have one edge or 2 edges touch the surface firstly and others touch the surface lately. As for end mills made by CNC, the four edges touch the surface at the same time, which can improve the life of end mill greatly.  Usually the life of end mill made by CNC machine is 40% longer than that of end mill made by common machine. Anymore, the end mill made by common machine only apply for low speed cutting (under 30m/min).3. Usually, we use 3 brands of tungsten carbide to make solid carbide tools. They are K10, K20, K30 and sometimes, we also use other brands of tungsten carbide for special usage.