“If you are dealing with harder ground conditions, like compacted soil, a more heavy-duty cast head auger with an aggressive offset tooth pattern will be more effective,” he states. This includes solid, fracturable rock and frozen ground.
For highly abrasive or consolidated-type soil formations, augers are available featuring tungsten carbide, conical-type tooling. “Normally referred to as bullet teeth, the same tooth design is used to mill concrete and asphalt from roads,” Von Ruden points out. “Conical tooling allows the same digging forces to be concentrated over a smaller surface area to ease penetration. In soft soil classifications, their overall digging performance can actually be less than a conventional boring head. However, with sufficient down force and rotation speed, these augers can achieve results in soil types never thought possible.”
That said, there’s a perception that tungsten carbide is the perfect solution for every soil classification. “The truth is tungsten carbide teeth can actually increase the power (torque) required to dig a hole over standard teeth,” says Von Ruden. “That’s because tungsten carbide teeth are usually more blunt in design to prevent chipping or breakage from impacting against rocks.
“Tungsten carbide better resists wear that standard teeth and properly used will normally allow for a significantly longer service life, especially in semi-consolidated soils like caliche, hardpan and other sedimentary materials,” he continues. “It’s critically important for the operator to have a good understanding of local soil types and the general condition of auger wear components to maximize his ROI.”