Introduction
In recent years, raise boring machines have been widely used in mining, hydropower, transportation, and municipal engineering projects. With construction advantages such as fast well-drilling speed, high safety standards, and low overall costs, they have gradually become an important method for drilling in underground engineering projects.
The report 《Global and China Raise Boring Rig Market Research and Development Outlook Forecast (2026–2032)》points out that, in terms of rock-breaking technology, optimizing the layout of cutting bits and their hydraulic power matching to increase drilling speed in extremely hard rock formations has become an inevitable trend.
How do tooth-embedded roller cutters work?
Raise boring drilling rigs use multi-row tooth-embedded cutters mounted on reaming bits. These cutters fracture and crush rock through the tangential forces and axial pressure generated by rotation, thereby forming the borehole.
What are the components of a tooth-embedded roller cutter?
It consists of a drill button, cutter body, seal, bearing, saddle, and cutter shell.
Among these, the drill buttons, bearings, and seals are the key factors that determine the performance and service life of the cutting bits. Additionally, the cutting bits at different positions on the drill bit can be classified into center cutters, main cutters, and side cutters. The center cutters are located at the center of the drill bit and are used to break up rock at the center of the borehole; the side cutters are located at the very edge of the drill bit; and the main cutters are positioned between the center cutters and the side cutters.
LOOKING RAISE BORING HARD ROCK ROLLER CUTTER
Our raise boring cutter is installed on TBM machine and raise boring machine reamer head. We could manufacture such roller cutter,which size is from 7”to 19”,they could be divided into 3-Row cutter,4-Row cutter,5-Row cutter.Its cutter shell chooses high strength alloy steel forging material,its surface is inserted with Tungsten carbide button.Inside the cutter shell we choose excellent tapered roller bearing .We could choose different tungsten carbide button according to different rock condition,therefore our roller cutter has long lifetime.
Application Parmeters
Compressive strength: ≥2500 MPa
To thoroughly break through extremely hard surface rock layers with uniaxial compressive strengths as high as 250–300 MPa, this roller cutters are made of tungsten carbide, which typically has a compressive strength ranging from 2,000 MPa to 5,000 MPa, providing high-strength rock-breaking capability.
Gear ring hardness: HRC 58-62
For medium-hard rock and formations with varying hardness, we strictly maintains the hardness of its hard-rock rollers within the range of HRC 58–62, achieving a level of hardness that ranks among the best in the industry.
Dynamic balance accuracy: G2.5 level
The roller cutter is designed in accordance with the internationally recognized standards ISO 21940-11 (formerly ISO 1940/1) and the Chinese national standard GB/T 9239.1. It achieves a high precision level of G2.5, significantly reduces vibration and noise, improves machining accuracy and mechanical efficiency, and extends the service life of bearings and equipment.
Sealing level: IP68
Designed to meet the highest dust-proof and continuous submersion (immersion) protection standards, this roller cutter completely prevents the ingress of silt and sand as well as lubricant leaks, protects against bearing damage, significantly extends tool life, and ensures your construction project runs smoothly.
Quick change support: Yes
As wear-prone consumables, roller cutters inevitably wear out gradually under high-intensity,long-term operation.therefore, modern shaft drilling rigs generally employ a modular design for their roller cutters. Our roller cutters can be replaced flexibly and safely.
Core material: high-strength alloy forged steel + carbide gear
The roller cutter features a composite structure consisting of a forged alloy steel body and carbide teeth. The forged steel body offers exceptional toughness, effectively absorbing impact loads underground. The carbide teeth possess ultra-high hardness, enabling efficient crushing and cutting of hard rock. This material combination perfectly blends high toughness with extreme wear resistance, significantly reducing cutter body fractures and premature tooth chipping, thereby greatly extending the tool’s service life. It is a professional, core tool designed to ensure efficient reverse-excavation operations.
Product Features
High-Efficiency Rock-Breaking Design with Mixed Tooth Profiles
To optimize rock-breaking efficiency and enhance the adaptability of the roller cutter, this roller cutter has adopted a dual-tooth design—a combination of wedge-shaped and spherical teeth—which increases the penetration depth into rock formations and boosts rock-breaking efficiency by 40%.
Specifically, the wedge-shaped teeth are suitable for rocks with low abrasiveness and relatively low hardness, allowing them to cut into and break the rock with minimal force; the spherical teeth perform well in breaking hard, highly abrasive rocks, effectively distributing pressure and reducing wear.
Low-Friction Ceramic Roller Bearing System
Taking advantage of ceramic materials’ wear resistance and high-temperature resistance, the roller bearings are made of ceramic, which reduces rotational resistance and ensures continuous, efficient performance under conditions of high thrust and high load.
Multi-layer Composite Reinforced Wear-Resistant Structure
The roller cutters are made of high-purity tungsten carbide alloy, which enhances the surface hardness of the teeth. Additionally, the substrate undergoes carburizing (heat treatment), forming a high-carbon hardened layer on the surface while maintaining toughness internally, thereby ensuring a low tool replacement frequency even when tunneling through highly abrasive rock formations.
Dual-Channel Sealing Protection System
The roller cutters feature high-pressure grease seals and a labyrinth-type dust-proof design, which effectively prevent abrasive rock dust from entering the bearings, thereby reducing the risk of bearing damage.
Elastic Tooth Seat Cushioning and Self-Cleaning Tooth Gap Design
The elastic tooth seat buffer absorbs impact loads and reduces the risk of alloy tooth fracture in hard rock conditions; the self-cleaning tooth gap design features debris grooves between the cutter teeth, which prevent the buildup of rock debris and ensure consistent rock crushing performance.
Multiple rows available
In high-efficiency reverse-tunneling operations using a raise boring machine, the “number of tooth rows” on the cutter head is the key factor determining rock-cutting efficiency and tool life. Different numbers of tooth rows essentially adjust the optimal balance between the energy concentration per tooth and the physical protection of the cutter body.
1. Difference in the Number of Rows
Low number of rows (e.g., 3 rows of teeth): Energy is highly concentrated, enabling aggressive cutting of intact, extremely hard rock through “bulk shearing and fracturing,” but vibration is severe, and the cutting edge is highly prone to chipping in complex strata.
High number of rows (e.g., 8 rows of teeth): The teeth are arranged very densely, forming a “protective armor” to resist the abrasive action of sand and gravel in highly erosive soft rock; however, when encountering hard rock, the axial pressure is easily diluted, causing the reamer head to slip.
2. Looking roller cutter
After comprehensively evaluating drilling rate of penetration (ROP), bearing load, and bottom-hole erosion and wear, we have carefully selected the optimal configurations with five, six, and seven rows. This series perfectly addresses drilling challenges across all terrain types, from medium-soft rock to extremely hard rock (UCS 80–180 MPa), and effectively eliminates dynamic oscillations in the drill pipe. It is currently the rock-breaking configuration in the industry with the broadest geological adaptability and the longest overall service life.
- Five-row tooth cutter (Hard Rock Pioneer): Features a wide tooth spacing design that maximizes the normal force per tooth. With deep tooth penetration, it effectively triggers volumetric crushing of rock, resulting in extremely fast cutting speeds in medium-hard and hard rock formations.
- Six-row tooth hob (All-Purpose Benchmark): Features a unique, even-numbered, equidistant, symmetrical tooth arrangement. It distributes operating forces extremely evenly, providing excellent, smooth torque feedback, and reduces one-sided wear by more than 40% compared to conventional hobs. It is specifically designed for formations with alternating soft and hard layers and multiple fractures.
- Seven-row tooth cutter (wear-resistant steel body): Features an ultra-high-density tooth arrangement, with the steel substrate surface almost entirely covered by super-hard alloy teeth. It offers excellent erosion resistance, effectively preventing secondary grinding of the cutter body by debris at the bottom of the well, and significantly extending the service life of the cutter in high-wear areas.
Conclusion
Drilling rig cutter heads are the core rock-breaking tools in hard rock shaft construction projects, and their performance directly determines construction efficiency and the success or failure of the project.
The Looking hard rock cutter heads are grounded in materials science and precision manufacturing. Through numerous innovations—including a hybrid tooth profile (wedge-shaped + spherical), ceramic roller bearings, a multi-layer composite wear-resistant structure, and dual-channel seals—they systematically address the challenges of rock breaking in extremely hard rock conditions (UCS ≥ 250 MPa). Field tests show that the hybrid tooth profile design increases rock-breaking efficiency by 40%, while IP68 sealing and G2.5 dynamic balance accuracy ensure long-term stable operation under high-load, highly abrasive conditions, significantly reducing the risk of bearing damage and cutter body failure.
To address varying geological conditions, Looking offers optimized combinations of five-, six-, and seven-row tooth configurations, tailored respectively for rapid advancement in hard rock, alternating hard and soft rock formations, and highly abrasive strata. These designs effectively distribute loads while maintaining single-tooth penetration force, thereby extending cutter life and reducing unplanned downtime. The modular, quick-change design further shortens on-site maintenance time and enhances construction continuity.
Furthermore, the comprehensive advantages of this hard rock roller cutters—including increased drilling speed, extended service life, and reduced spare parts consumption—directly translate into a significant reduction in drilling costs per meter and a controllable shortening of project timelines. Strictly compliant with ISO and GB standards, these products deliver performance on par with or even superior to international competitors, providing users with a cost-effective and highly reliable domestic solution for challenging underground engineering projects. In the future, with the integration of intelligent monitoring technology, this product series is expected to further drive the continuous evolution of reverse-borehole drilling toward greater efficiency, intelligence, and lower costs.
