Product Introduction
RockHound R32-H28-R28 Threaded Drifter Rod is a high-performance top hammer drilling component purpose-built for underground tunneling, drifting, and development drilling. Featuring an R32 male thread on the shank end and an R28 female thread on the bit end, this tapered-thread drifter rod is engineered to deliver efficient energy transfer from the rock drill to the drill bit while maintaining structural integrity under continuous high-frequency impact loading.
Manufactured from ZK22CrNi3Mo low-alloy case-hardening steel and processed through a full-body carburizing heat treatment, each rod achieves the optimal combination of case hardness and core toughness — the two most critical properties for combating thread wear, bending fatigue, and rod breakage in demanding rock formations.
Key Features
Premium ZK22CrNi3Mo Alloy Steel
This chromium-nickel-molybdenum low-alloy steel grade provides high core impact toughness (typically >80 J Charpy) paired with excellent hardenability, making it the industry benchmark material for percussion drill rods.
Full-Body Carburizing Heat Treatment
The carburizing process diffuses carbon into the rod’s surface layer, producing a hardened case of HRC 58–62 while preserving a tough, ductile core. This dual-zone microstructure dramatically extends fatigue life compared to through-hardened rods.
Precision CNC-Machined R32 / R28 Threads
Both thread ends are ground to tight dimensional tolerances, ensuring full thread-flank contact, minimal energy loss at joints, and reduced risk of thread seizure or premature decoupling under dynamic loads.
H28 Hexagonal Cross-Section (28 mm / 1-1/8 in)
The 28 mm hex shank interfaces precisely with the drifter chuck, ensuring positive rotational drive transmission. The hex profile also facilitates manual rod uncoupling in confined underground headings.
Straightness Control
Controlled cooling and straightening post-heat-treatment limits rod bow to industry-standard tolerances, reducing hole deviation and collar wear during long-hole tunneling rounds.
R32 Threaded with R28 Hex Drifter Rods Specifications
R32 drifter rods with R28 hex shank are widely used in tunneling, mining, and quarrying for high-frequency top hammer drilling. Choose the right length for optimal energy transfer and penetration rate.
| Product Code | Drifter Rod Type | Length (mm) | Length (ft / in) | Hex H (mm) | Hex H (in) | Weight (kg) |
|---|---|---|---|---|---|---|
| 276-2826-5453 | R32-H28-R28 | 2,600 | 8′ 6-3/8″ | 28 | 1-1/8″ | 13.0 |
| 276-2830-5453 | R32-H28-R28 | 3,090 | 10′ 1-5/8″ | 28 | 1-1/8″ | 15.9 |
| 276-2837-5453 | R32-H28-R28 | 3,700 | 12′ 1-5/8″ | 28 | 1-1/8″ | 18.5 |
| 276-2840-5453 | R32-H28-R28 | 4,005 | 13′ 1-43/64″ | 28 | 1-1/8″ | 20.5 |
| 276-2842-5453 | R32-H28-R28 | 4,265 | 13′ 11-1/2″ | 28 | 1-1/8″ | 21.3 |
| 276-2843-5453 | R32-H28-R28 | 4,305 | 14′ 1-31/64″ | 28 | 1-1/8″ | 21.5 |
Thread Specification: R32 (shank end) × R28 (bit end) | Hex Section: H28 — 28 mm / 1-1/8 in | Material: ZK22CrNi3Mo | Heat Treatment: Carburizing
Applications
The R32-H28-R28 drifter rod is designed for the following underground and surface drilling operations:
Tunneling & Drifting
Horizontal and sub-horizontal development headings in hard rock mines, railway tunnels, hydropower caverns, and road tunnels where consistent hole straightness and long rod life are critical.
Underground Mining
Production drifting, crosscutting, and ore development drives. The rod’s carburized surface layer resists the abrasive wear common in siliceous and quartzite formations.
Civil & Geotechnical Engineering
Rock bolt hole drilling, pre-splitting, and perimeter blasting where precision hole placement is required.
Drill Rig Compatibility
The R32-H28-R28 configuration is compatible with top hammer rock drills from leading OEM platforms including Epiroc (Atlas Copco), Sandvik, Furukawa, and Montabert, as well as their equivalent Chinese and aftermarket drifter models.
Drilling String Compatibility
For correct assembly, the R32-H28-R28 drifter rod must be paired with:
- Shank Adapter: R32 female thread, H28 hex chuck interface
- Coupling Sleeve (if used): R28 × R28 coupling
- Drill Bit: R28 male threaded button bit or cross bit
Note:Verify your drill rig’s chuck size (H28 = 28 mm hex) and thread standard before ordering. Mismatched thread profiles will cause premature coupling failure and energy loss.
How to Select the Right Length
Rod length selection should be based on your drill rig’s feed beam travel length and the planned advance per round. As a general guideline:
| Recommended Length Range | Best Application & Benefits – Top Hammer Drifter Rods |
|---|---|
| 2,600 mm (8′ 6″) | Suits compact jumbo rigs and short-advance development rounds in restricted headings; ideal for narrow tunnels, low-profile equipment, and confined spaces where maneuverability is critical. |
| 3,090–3,700 mm (10’–12′) | Standard range for conventional single-boom tunneling jumbos with 3–4 m advance cycles; provides balanced energy transfer, good hole straightness, and efficient collaring in typical tunneling operations. |
| 4,005–4,305 mm (13’–14′) | Maximizes advance per round on long-feed drifters; reduces re-collaring frequency, improves cycle time, and boosts overall productivity in large-scale development or production drilling with extended feed lengths. |
Maintenance & Best Practices
Proper maintenance is the single most effective way to extend rod service life and reduce cost-per-meter:
Thread Lubrication
Apply certified rock drill thread grease to all male threads before each connection. Never drill with dry threads; dry running causes galling and accelerated thread wear within minutes.
Reduced-Power Collaring
Begin each hole at 50–60% impact power until the bit is collared at least 150–200 mm deep. Full-power collaring causes severe bending stress at the rod’s hex-to-thread transition zone.
Rotation Inspection
Monitor for abnormal rotation resistance or vibration, which may indicate a bent rod, worn coupling, or damaged bit skirt.
Thread Inspection
Regularly inspect both thread ends for signs of mushrooming, cracking, or metal flow. Remove any rod with a cracked or badly mushroomed thread immediately to prevent in-hole breakage.
Flushing
Maintain adequate water or compressed-air flushing throughout the drill cycle to evacuate cuttings, cool the bit, and prevent cuttings re-grinding that accelerates rod wear.
Storage
Store rods horizontally on padded racks in a dry, covered environment. Avoid contact with chloride-bearing water or acidic drainage to prevent corrosion pitting on the heat-treated surface.
Packaging & Warehousing
- Framed packaging:If wooden crate packaging is required (custom-made), confirmation with logistics is necessary (time and cost).
- Marking Instructions: Laser marking or steel stamping is a value-added process; specifications need to be confirmed separately.
Related Products
FAQ
R32 and R38 refer to the thread diameter on the shank (drill end) of the rod. R38 has a larger thread diameter and is used with higher-power drifters; R32 is the standard for light to medium drifting. Always match the rod's shank thread to your shank adapter.
Yes. The R32-H28-R28 configuration is a standard dimension for Epiroc Boomer series tunneling jumbos and equivalent rigs. Confirm your shank adapter thread and hex size before ordering.
ZK22CrNi3Mo is a Chinese standard designation for a low-alloy case-hardening steel containing chromium (Cr), nickel (Ni), and molybdenum (Mo). These alloying elements enhance hardenability, core toughness, and temper resistance — properties essential for percussion drill rod performance.
After carburizing heat treatment, the case hardness is HRC 58–62, with a case depth typically in the range of 0.8–1.5 mm depending on rod geometry. Core hardness is maintained at HRC 38–45 to preserve impact toughness.