In top hammer drilling, a taper drill rod (also called tapered drill steel) is a specialized drill rod with a gradually decreasing diameter (taper) along its length. This design enhances energy transfer, reduces fatigue stress, and improves alignment in the drill string. Taper rods are commonly used in rock drilling, quarrying, and mining with hand-held rock drills.

Popular degree: 6°, 7°, 11°, 12°

Popular Steel dimensions(Hexagon opposite side dimension):   Hex22mm, Hex25mm

Shank length: 108mm, 159mm

Rod effective length: 400mm-7000mm

Technology: Carburized / Non Carburized.

1. Carburized Taper Drill Rods

Advantages:

Extreme Surface Hardness – Resists wear from rock abrasion.

mproved Fatigue Resistance – Handles repeated impact better.

Longer Lifespan – Lasts 2–3× longer than non-carburized rods in hard rock.

Better for High-Stress Drilling – Ideal for granite, basalt, and abrasive formations.

Disadvantages:

High cost – Due to additional heat treatment.

Brittle Surface Risk – If over-carburized, micro-cracks may form.

Best For:

Hard rock drilling (quarries, mining).

High-impact applications (deep blast holes).

2. Non-Carburized Taper Drill Rods

Advantages:

Lower Cost – No carburizing step reduces manufacturing expense.

Less Brittle – More resistant to sudden fractures.

Disadvantages:

Faster Wear – Softer surface degrades quicker in abrasive rock.

Shorter Lifespan – May fail earlier under heavy cyclic loading.

Best For:

Softer rock formations (limestone, sandstone).

Short-hole drilling (e.g., rock bolting, anchoring).

Budget-conscious operations.