Twist drill bit Irwin 4 mm — model 10502547, 1 piece

Irwin twist drill bit 4 mm (model 10502547) is a single-piece high-speed steel (HSS) cobalt bit designed for standard and demanding metal drilling tasks. With 5% cobalt enhancement and a heavy-duty web construction, this 4 mm bit offers improved heat and abrasion resistance for use in hand drills and drill presses. The 135° split point reduces bit walking and starts cuts cleanly, while compliance with DIN 338 standards ensures consistent geometry and reliable performance in workshop and industrial environments.

Advantages

The 5% cobalt composition provides increased wear and heat resistance compared with standard HSS bits, enabling longer life when working with alloyed and hardened steels. The heavy-duty web construction increases strength at the core of the bit to resist breakage under higher axial loads. A 135° split point produces fast bite and reduced wandering on the workpiece surface, improving accuracy from the first contact. Manufactured to DIN 338 tolerances, the bit delivers repeatable diameter control and cutting geometry suitable for professional applications.

Suitable for

• Drilling holes in alloyed steel and other ferrous metals
• General metal fabrication and maintenance tasks
• Use in hand-held drills and drill presses for small projects and repairs

Key specifications

• Type: Twist drill bit, HSS with 5% cobalt
• Diameter: 4 mm
• Overall length: 75 mm
• Point angle: 135° split point
• Shank: Cylindrical
• Pack quantity: 1 piece

How to use

Secure the 4 mm Irwin twist drill bit in a drill chuck and ensure it is tightened to prevent slippage. Select an appropriate cutting speed and feed for the material being drilled; lower speeds are recommended for harder or heat-treated steels to reduce heat buildup. Use cutting fluid or coolant when drilling ferrous and stainless steels to extend bit life and improve chip evacuation. Begin drilling with a steady, controlled feed rate and let the split point establish the hole before increasing pressure.

Usage recommendations

For best results, use this HSS cobalt 4 mm bit with proper coolant and moderate speeds when working with alloyed or hardened steels. Avoid excessive side loads and peck-drilling in deep holes to prevent overheating and extend tool life.