Classified by the number of teeth.

This is the most basic classification method. The number of teeth directly affects the coverage area at the bottom of the well and the balance of forces exerted. The mainstream choice is three-tooth bits, while single-tooth and two-tooth bits are more commonly used in specialized applications.

Single-tooth roller cone bit: It features a single rotatable roller bit with a compact structure, making it ideal for operations in confined spaces such as small-diameter drilling, sidetracking in directional wells, or casing windowing. The roller-bit teeth are typically arranged in a helical pattern and achieve rock-breaking through high-speed self-rotation. Its advantages include high maneuverability and fast drilling speed; however, its disadvantages include concentrated stress distribution, making it unsuitable for hard rock formations and large-diameter drilling.

Dual-cone drill bit: Two symmetrically arranged roller bits, with strong biting force, are suitable for vertical drilling in medium-hard rock formations. Compared to single-roller bits, they distribute forces more evenly and have a wider rock-breaking range. However, compared to three-roller bits, they leave a small blind spot at the bottom of the wellbore, and their use is gradually declining. They are now mainly employed for drilling specific mine water wells.

Three-cone drill bit: The most widely used type in industry features three roller bits evenly spaced at 120°, providing complete coverage of the well bottom with no dead zones. This design ensures balanced force distribution and excellent vibration resistance. It is suitable for drilling through a wide range of rock formations—from soft to hard—and can meet the needs of most applications, including oil drilling, mining operations, and infrastructure construction drilling. It is the most versatile roller-bit drill bit available.

Multi-tooth drill bits (four teeth or more): Rarely used, it is primarily employed in ultra-large-diameter drilling operations (such as deep geological exploration wells and tunnel advance boreholes). By increasing the number of roller bits, this method distributes pressure more evenly and reduces wear on individual teeth. However, due to its complex structure and high cost, it is used only under special operating conditions.

Classified by tooth profile structure

The tooth profile directly determines the rock-breaking method and is broadly categorized into two types: milling teeth and brazed teeth. These are suited to different rock hardness levels and serve as one of the key criteria for selection.

Milling-tooth roller cone bit: The tooth profile is directly milled from the body of the roller bit, and its material is consistent with that of the roller bit itself (typically high-strength alloy steel); some bits undergo surface hardening treatment. The tooth profiles are mostly wedge-shaped or spoon-shaped, and they primarily break rock through cutting action. They are suitable for soft to medium-hard rock formations such as mudstone, sandstone, and shale. Their advantages include low cost and simple manufacturing; however, their disadvantage is poor wear resistance, making them prone to rapid wear and failure in hard rock formations.

Crown bit with toothed cutters: The surface of the roller bit is pre-equipped with holes for embedding individual hard alloy teeth (such as tungsten-cobalt alloys or polycrystalline diamond compact inserts). These hard alloy teeth have a hardness significantly higher than that of milled teeth, offering exceptional wear resistance and impact resistance. By combining cutting, crushing, and impact actions, these bits are well-suited for drilling into medium-to-extremely hard rock formations, such as granite, limestone, and basalt. Based on tooth geometry, they can be further classified into ball teeth, sharp teeth, and wedge-shaped teeth. Ball teeth are ideal for breaking up softer rock formations, while sharp teeth are better suited for hard and brittle rock layers; they currently represent the mainstream choice for high-end drilling operations.

Classified by applicable rock strata

Based on the rock layer’s hardness, abrasiveness, and integrity, we designed and optimized tooth profiles, roller speeds, and bearing structures in a targeted manner, dividing them into three major categories:

Soft Formation Roller Bit: The teeth are primarily milled, with long and sharp tooth profiles and wide tooth spacing, which facilitates the efficient removal of rock cuttings and prevents mud from encasing the drill bit. The roller bits rotate at relatively high speeds, and their bearing designs emphasize lubrication performance, making them well-suited for soft rock formations such as mudstone, shale, and loose sandstone—rocks that are prone to plastic deformation.

Mid-hard formation roller cone drill bit: Mostly featuring a toothed structure, the teeth are designed to balance cutting and crushing actions. The tooth spacing is moderate, and the gear wheel material is coated with an enhanced wear-resistant layer. This model is suitable for dense sandstone, limestone, and weakly abrasive rock formations, striking a balance between rock-breaking efficiency and service life, making it a versatile mid-range type.

Hard Formation Roller Cone Bit: The drill bit features fully embedded carbide ball teeth or wedge-shaped teeth that are short and robust. The body of the roller cone is thickened, and the bearings employ a high-strength sealing structure capable of withstanding severe impacts. It is suitable for drilling extremely hard and highly abrasive rock formations such as granite, basalt, and quartzite, and is widely used in deep oil and gas drilling as well as hard-rock excavation in mining operations.

Classified by Special Drilling Scenarios

Designed for special operating conditions such as directional wells, horizontal wells, and offshore drilling, with differentiated structural optimizations:

Directional well roller cone drill bit: The roller bits are arranged asymmetrically, giving the drill bit strong lateral cutting capability and enabling it to work in conjunction with directional tools to adjust wellbore trajectories. The bearings feature a torsion-resistant design that prevents the drill bit from shifting during drilling, making them suitable for non-vertical drilling scenarios such as horizontal wells and inclined wells.

Marine drilling roller cone bits: Highly corrosion-resistant, it is made from an alloy material that resists salt spray and seawater erosion. The bearing features excellent sealing performance, effectively preventing seawater ingress and subsequent failure. At the same time, its compact structure makes it well-suited for the confined working spaces on offshore drilling platforms.

Core-bit roller cone drill bit: The center is equipped with a core-taking channel that allows for the simultaneous rock breaking and retrieval of core samples from underground rock formations, which can be used for geological exploration and oil-and-gas reserve assessment. The roller bits are arranged around the core-taking channel to balance rock-breaking efficiency with core-integrity preservation.