Selecting the right insert requires matching the substrate and coating to the workpiece material. For steel, look for CVD-coated carbide grades (like P25) for heat resistance; for stainless steel or superalloys, PVD-coated grades offer better edge toughness. Ensure the chipbreaker geometry aligns with your operation—finishing, medium, or roughing—to prevent chip wrapping and tool breakage. Always verify the ISO/ANSI coding system (e.g., CNMG, WNMG) to ensure compatibility with your existing tool holders.