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R32 Self-Drilling Anchor Rock Bolt

ONTON® R32 Self Drilling Anchor features a wide range of applications such as soil nails, micropiles, rock bolts, or ground anchors. It is applied to self-drilling ground control solution used in Civil Engineering and underground construction.

The systems have been called as “self-drilling anchoring” or “injection piling” because the hollow fully-threaded bar serves as both the drill string and the grouted anchor, thus the installation is performed in a single operation.


Civil Engineering Underground Mining and Tunneling
1. Pile foundation 1. Stabilization of tunnel portals, trenches, and cut-and-cover areas
2. Slope and embankment stabilization 2. Forepoling
3. Reinforcement of excavation pits and retaining walls 3. Face stabilization
4. Foundation of pylons and wind mills 4. Radial rock bolting
5. Anchorage of avalanche protection structures and noise barriers 5. Roof and rib bolting
6. Injection works 6. Injection works



R32 Rock Bolts Description

  • The anchor rod features a hollow bore for flushing, or simultaneous drilling and grouting.
  • It is manufactured in accordance EN10210-1:2006 standard.
  • The Standard thread profile is according to ASTM A615 and ISO 10208. This makes the bond between the rod and grout concrete strong enough.
R-thread Φ32-38 mm according to ISO 10208

R-thread Φ32-38 mm according to ISO 10208

  • The manufacturing process assures the balance of yield strenght and ductility. Prevent hollow bar anchors from sudden fracture while drilling.

Bending Test hollow bar

  • All parts of the system can be supplied with surface treatment, with a hot-dip galvanised finish or with a duplex coating.
galvanized self-drilling hollow bar anchors

galvanized self-drilling hollow bar anchors

 Typical technical performance for R38 Hollow Threaded Drilling Anchor Rock Bolt:
R32 SDA Hollow Bar Specifications
SDA Size Outer Diameter (mm) Inner Diameter (mm) Ultimate Load (kN) Yield Load (kN) Weight (kg/m)
R32L 32 21.5 210 160 2.6
R32N 32 20.5 280 230 2.9
R32S 32 16.0 360 280 3.6
Other standards available on request


The hexagonal and spherical nuts are made from high precision steel (40Cr,HRC 20-25) to meet the stringent demands on anchor specifications and the daily uses of reinforcement work.
All nuts exceed the ultimate strength of the rod.


The hollow bar is continuously threaded, it can be cut and coupled anywhere along its length.
The coupling enables direct end-to-end energy transmission between each bar, reducing losses and ensuring maximum percussive energy at the drill bit.


The sacrificial drill bit is an important part of the self drilling anchoring system.
Choose suitable bits according to different soil type.

X Forged cross-cut drill bit
XX Two stage cross-cut drill bit
EX Cast hardened cross-cut drill bit
EXX Tungsten carbide cross-cut bit
EC Hardened tri-crescent drill bit
ECC Tungsten carbide tri-crescent bit
EY Hardened tri-crescent drill bit
ES Cast/hardened button drill bit
ESS Tungsten carbide button drill bit


The core of the Onton Self-Drilling Anchor Bolt is a hollow, thick-walled, central drilling rod with a drill bit at the top. The system is modular, meaning that the most appropriate configuration can be put together to suit on-site circumstances and the forces that apply.

The self-drilling anchor bolts are available in the steel grade S460NH and other common types. All of steel materials are produced according to EN 10210-1 “Hot finished structural hollow sections of non-alloy and none grain steels” and have excellent capacity to the short time simultaneously dynamic loads (torque, frequent percussion impact, bending moments) during drilling as long-term load and durability.


Fast drilling and grouting installation
Similar installation methods for all ground conditions
Ability to work with small drill rigs without casing in restricted headroom conditions
High standard of quality control from production stage to installation of the Self-Drilling Hollow Bar Anchor Bolt ensures consistent quality
High yield strength
Good impact strength
Good ductility
Excellent weldability

Our Onton Steel Drilling anchor Systems comply with the requirements of design following the US standards:

The Steel Hollow Bar Anchor Bolts can be customized to fulfill different requirements in different areas. And we offer a full-scale stock of all necessary components such as couplings, nuts, drill bits (for various soil conditions), centralizers, and plates.

Related Products

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Galvanized Self-Drilling Anchor Hollow Bars
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Drill Bits for self-drilling anchoring system
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R38 Hollow Threaded Drilling Anchor Bolt
A good alternative to DYWI Hollow Drill Rods or MAI SDA. Self-drilling, injection anchoring systems for underground works.