Mimhooy 10Pcs 5mm Cobalt HSS Drill Bit for Drilling Stainless Steel and Hard Metal

• Cobalt Drill Bit: Made of M35 grade cobalt steel, hardness up to HRC63-65, wear-resistance and durability.
• Self-centring Design: 135°self-centring tips, increase cutting speed and prevent walking, clear chips and particles faster.
• For Most Material: Particularly successful in cutting through hard metals such as stainless steel and cast iron, also can be used for softer materials like wood, aluminum alloy.
• Performance: Fast drilling results with low contact force without pre-punching or pre-drilling.
• Precision Ground: Fully ground so that it's cutting diameter is seriously accurate and the lifespan is prolonged in comparison to non-ground alternatives.

Usage Instructions 1. Twist drills are cutting tools primarily used for drilling metal, hence controlling rotational speed is crucial. 2. Recommended rotational speed: 100-800 RPM. Larger diameters require slower speeds. M35 cobalt-alloyed high-speed steel twist drills possess a hardness of HRC 63-65, suitable for drilling metals below 38 degrees. 3. When operating hand drills, adjust the speed carefully; excessive speed may damage the drill bit. 4. Avoid hammering during use. Secure the workpiece firmly; oscillation during operation may fracture the drill bit. 5. When drilling high-hardness or impurity-rich metals, reduce speed below normal drilling rates. Coolant application enhances performance. 6. When machining thicker materials, promptly clear any abnormal chip formation. Tips for Drilling Stainless Steel with a Hand Drill 1. When drilling with a hand drill, ensure the twist drill bit is perpendicular (90°) to the stainless steel plate. 2. For holes larger than 6mm, first use a 3.2mm-4mm drill bit to create a pilot hole, then enlarge the hole with a larger drill bit. 3. The drill chuck must securely grip the twist drill bit. Shorter twist drill bits are preferable, and the cutting edges need not be overly sharp or pointed. 4. The drill's rotation speed should be between 80-120 rpm for optimal results. Higher speeds will cause the drill to overheat and burn out, resulting in annealing of the stainless steel plate. Once annealed, drilling will become impossible.