Material Comparison Views: 26

For 304 stainless steel you must use cobalt HSS (HSS-E, 5-8% cobalt) or carbide countersinks - never standard HSS! Standard HSS lacks red hardness, its hardness drops fast at high temperature, and each tool only machines 500-1000 pieces before wearing out. Cobalt HSS with 5-8% cobalt keeps hardness above HRC60 even at 600 degrees C, machining 3000-6000 pieces in 304 stainless - 3-6x the life of standard HSS. Recommended setup: cobalt HSS (M35, 5% cobalt) + TiAlN nano-coating + 3-flute design. TiAlN is 3500HV, lowers friction and reduces welding; 3-flute cutting is smooth and suppresses vibration marks. Lihao Technology cobalt HSS 3-flute countersinks are designed for stainless steel with 3x+ the life of ordinary tools.