Drill bit Proline 78120K — metal drill bit Ø12 mm, length 151 mm, 1 pc

The Proline 78120K metal drill bit is a single HSS-Co twist drill designed for creating precise 12 mm holes in metal. With an overall length of 151 mm and a 135° point angle with chamfering adjustment, this drill bit is machined entirely by grinding to ensure accuracy and straightness of drilled holes. The bit is produced from high-class high-speed steel with 5% cobalt, offering improved heat resistance and wear performance when drilling hard and alloyed steels, stainless steels, titanium, cast iron and other difficult-to-machine materials.

Advantages

This 12 mm Proline drill bit combines a 135° split point for fast, low walking starts and reduced need for center punching with full grinding manufacture for dimensional accuracy and straightness. The 5% cobalt HSS composition increases thermal stability and tool life during high-temperature cutting, while the geometry and chamfering adjustment help maintain efficient chip evacuation and consistent hole quality. Supplied as a single piece in a blister pack, the bit is suitable for use with standard drill chucks and machine tools when appropriate speeds and coolant are applied.

Suitable for

• Drilling through alloyed and high-strength steels
• Creating holes in stainless and acid-resistant steels
• Working with titanium and creep-resisting steels
• Drilling cast iron and other difficult-to-machine metals
• Use in hand drills and drill presses with correct speeds and cooling

Key specifications

• Drill type: HSS-Co (high-speed steel with 5% cobalt) twist drill
• Diameter: 12 mm
• Overall length: 151 mm
• Point angle: 135° with chamfering adjustment (split point)
• Manufacturing method: fully ground flutes for high accuracy and straightness
• Material suitability: high-alloy steels, stainless and acid-resistant steels, titanium, creep-resisting steels, cast iron

How to use

Install the 12 mm Proline drill bit securely in a compatible chuck, ensuring correct clamping depth and concentricity. Select an appropriate cutting speed and feed for the workpiece material; use lower speeds and steady feed when drilling hard, heat-resistant alloys. Apply cutting fluid or coolant for heat control and improved chip evacuation when drilling stainless steels, titanium or high-alloy steels. Start drilling with light pressure to establish the hole, then increase to a steady feed while maintaining alignment and avoiding side loads on the bit.

Usage recommendations

For best results, use the drill with a rigid setup (drill press or CNC) when possible, maintain recommended speeds for the specific material, and keep the cutting zone cooled. Re-sharpen slightly rounded points only with appropriate grinding equipment to preserve the 135° geometry and avoid excessive heat during reconditioning.