What Does Helix Angle Mean?
The Helix angle of a drill bit, such as that found on a continuous flight auger (CFA), is defined as the angle between the screw flight of a helix and any line perpendicular to the screw axis or pitch. The Helix angle can be calculated by the following expression:
Helix angle = arctan (screw pitch/diameter of the screw thread)
Trenchlesspedia Explains Helix Angle
Different helix angles on drill bits are suitable for different requirements and situations. A high helix angle improves penetration efficiency and increases the force pushing the soil or other material out of the hole being bored. However, high helix angles decrease the helical cross-sectional area and weaken the body of the drill, making it suitable for cutting softer, lower strength materials.
On the other hand, a lower helix angle increases the helical cross-sectional area and drill body strength, making it suitable to drill harder materials.