When sourcing radius milling cutters, you must prioritize Substrate Material and Coating Technology. For high-speed machining, look for Ultra-Fine Micro-Grain Carbide (0.4μm-0.6μm) to ensure edge toughness. The Coating (e.g., AlTiN, TiSiN, or DLC) is critical; for example, TiSiN is preferred for hardened steels up to HRC65, while DLC (Diamond-Like Carbon) is essential for non-ferrous metals like aluminum to prevent built-up edge. Additionally, verify the Radius Tolerance, which for precision mold making should be within ±0.005mm.