Drill bit Bosch HSS Twist Drill Bit Cobalt 7 mm, single piece

Bosch HSS Twist Drill Bit Cobalt 7 mm is a single-piece high-speed steel twist drill designed for drilling metal and other hard materials. The bit features a cobalt-alloy treatment to improve heat resistance and wear performance, a pointed split-point 135° tip for active cutting and precise centring, and two cutters with two flutes for efficient chip removal. Manufactured to DIN 338 with diameter tolerance h8 and a cylindrical shank equal to the drill diameter, this 7 mm twist drill is intended for use in drill stands and drill drivers and is suitable for alloyed and non-alloyed steels, stainless steel, cast iron and cast steel, and other metalworking tasks.

Advantages

The cobalt-alloyed HSS construction provides increased hardness and heat protection compared with standard HSS, extending tool life during continuous or heavy-duty drilling in stainless and alloyed steels. The split-point 135° tip reduces walking and improves centring, enabling accurate starts without pilot drilling in many applications. Two cutters and two flutes accelerate chip evacuation, lowering heat build-up and preserving cutting edges for longer service life. The cylindrical shank fits standard three-jaw chucks, allowing straightforward mounting in drill drivers and bench drills.

Suitable for

• Drilling holes in stainless steel and acid- or heat-resistant steels
• General metalworking and fabrication tasks
• Repair and maintenance of machinery and equipment
• Use in drill stands and handheld drill drivers with three-jaw chucks

Key specifications

• Drill type: HSS twist drill with cobalt alloy
• Tip angle: 135° split-point for reduced wandering
• Diameter: 7 mm
• Total length: 109 mm
• Flutes: two flutes and two cutters for chip removal
• Shank: cylindrical shank equal to drill diameter
• Manufacturing standard: DIN 338, Type N flute geometry
• Material suitability: alloyed and non-alloyed steel, stainless steel, cast iron, cast steel
• Supply: single piece

How to use

Secure the 7 mm cylindrical shank in a compatible three-jaw chuck and ensure the drill is properly tightened. Select an appropriate cutting speed and feed for the material being drilled; for stainless and alloyed steels use lower speeds and steady pressure to avoid overheating. Use a centre punch or pilot hole if extreme precision is required, although the 135° split-point tip often enables accurate starts without pre-drilling. Apply suitable cutting fluid or coolant when machining stainless or heat-resistant steels to extend tool life and improve chip evacuation. Withdraw the bit occasionally to clear chips during deep holes.

Usage recommendations

For prolonged service life when drilling stainless steel and heat-resistant alloys, use reduced cutting speeds, consistent coolant or cutting fluid, and moderate feed. Inspect the cutting edges regularly and replace the bit if chipping or excessive wear is observed. Avoid excessive lateral forces and ensure correct chuck alignment for accurate hole quality.