Spiralbohrer

Spiralbohrer, known in English as twist drill bit, is a cylindrical cutting tool with helical flutes along its length. It is designed to bore round holes in materials such as metal, wood, and plastics. The tip provides the primary cutting action, while the flutes remove chips from the hole to allow continued cutting.

Most spiralbohrer are intended for right-hand rotation, and clockwise drilling is the standard. Left-handed variants exist for special applications. They come in various lengths and flute counts; two-flute designs are common and suitable for many tasks, while more flutes can improve rigidity and heat handling but may hinder chip evacuation in metal.

Materials and coatings vary: high-speed steel (HSS) twist drills cover a wide range of uses, while cobalt alloys (such as M42) are chosen for harder metals. Carbide-tipped types offer extended wear resistance in demanding applications. Coatings like titanium nitride or black oxide can reduce wear and corrosion. Standards such as DIN 338 and ISO guidelines govern the geometry and tolerances of common twist drills.

Application and usage: spiralbohrer are widely used in hand drills and drill presses. For metal drilling, appropriate speed, feed, and cooling or cutting fluid help manage heat and extend tool life. For wood and plastic, lower cutting speeds and proper chip evacuation are important. Workpieces should be clamped securely, and drills should be kept sharp and properly aligned to avoid deflection.

Variations include different lengths, shank shapes (round or hex), and point angles (around 118 degrees for general use or 135 degrees for harder materials). Proper selection and maintenance are key to reliable results.