Diamond Bit

Electroplated Diamond Reaming Shells

Product Positioning: The Gauge Protector in the Drill String

In diamond core drilling and conventional exploration, the reaming shell is far more than an accessory to the bit—it is a critical component that determines borehole trajectory accuracy and drill string longevity. Our electroplated diamond reaming shells are engineered specifically for single-tube and double-tube drill systems, serving the essential function of conditioning the borehole wall, maintaining gauge diameter, and reducing vibration and wear on the drill string . As the bit fractures rock, the borehole wall often develops slight under-gauge sections or irregular steps. The reaming shell, positioned immediately behind the bit, performs a secondary calibration pass with a precise outer diameter, ensuring smooth casing installation and significantly lowering frictional resistance during high-speed rotation.

Single-Tube vs. Double-Tube Compatibility

Single-tube reaming shells are designed for conventional single-tube drilling. Their compact structure and unobstructed water flow make them stable performers in coal field exploration, shallow water well drilling, and engineering geological surveys. The design emphasizes cuttings evacuation efficiency and resistance to back-reaming, maintaining consistent hole diameter under both mud and water flush conditions.

Double-tube reaming shells are optimized for wireline double-tube systems, working in coordination with the inner tube assembly and core retrieval mechanism. In deep holes and complex formations, double-tube shells must withstand higher torque and lateral loads while maintaining outer diameter wear resistance through frequent tripping and wireline retrieval. Our double-tube series utilizes thickened steel bodies and optimized diamond distribution, delivering extended gauge life in abrasive formations such as granite, basalt, and tight sandstone.

The Engineering Value of Electroplating

The core advantage of electroplated diamond technology lies in low-temperature manufacturing and controllable grit size . Unlike powder metallurgy sintering or brazing, electroplating occurs in an ambient-temperature electrolyte bath, with diamond particles mechanically locked onto the steel body surface. This avoids potential thermal degradation of the substrate’s mechanical properties. The result is a reaming shell that retains the toughness of its steel body while carrying a sharp, micro-cutting diamond layer.

In actual drilling, the protrusion height of the electroplated layer is precisely controlled: excessive protrusion leads to premature diamond pull-out, while insufficient protrusion reduces cutting efficiency. By adjusting grit size and plating thickness, our shells engage the formation quickly during the initial reaming phase and maintain stable outer diameter throughout their service life, reducing trip-outs caused by under-gauge holes.

Full Size Range and Application Fit

Our standard reaming shell outer diameters span 36 mm to 330 mm , covering geological exploration standard sizes, water well drilling common diameters, and large-diameter engineering requirements. Specific sizes include: 36, 46, 56, 59, 73, 75, 89, 91, 94, 108, 110, 127, 130, 146, 150, 168, 171, 194, 200, 219, 245, 252, 280, and 330 (mm). These sizes mate with single-tube bits, double-tube bits, and wireline core barrels. Thread forms and coupling configurations are customized to customer drill string standards.

Typical Applications

  • Water well drilling : At the overburden-bedrock interface, reaming shells condition the borehole wall, preventing under-gauge sticking and ensuring smooth screen and casing installation.

  • Solid mineral exploration : In wireline coring, double-tube shells wear in sync with diamond bits, maintaining hole diameter stability and reducing core blockage caused by irregular walls.

  • Engineering geological investigation : For highway, railway bridge, and high-rise foundation surveys, single-tube shells paired with conventional drill strings maintain hole verticality and diameter precision in sand-gravel and weathered rock layers.

  • Mine goaf and roadway exploration : Large-diameter shells maintain gauge in gas drainage holes, ventilation holes, and water exploration holes, reducing rod wear and rotational drag.

Selection Guidelines

When selecting a reaming shell, focus on formation abrasiveness and bit OD matching . In highly abrasive hard rock, finer diamond grit with thicker plating is recommended for extended gauge life. In soft to medium-hard formations, slightly higher protrusion improves penetration rates. Shell OD should typically match or slightly exceed bit OD by 0.5–1 mm to compensate for normal bit crown wear. We provide customized grit and plating thickness matching based on customer drill string drawings and formation conditions.