Follow the explanation
Back to the model ↑How the parts work together
Three cones, four rotations
The body turns about the drillstring axis while all three cones also turn around their individual inclined axes. Orbit below the bit to follow the insert rows.
Look behind a cone
Separate the cutting assembly to reveal the supporting journals. This is an inspection pose: the displaced cones are no longer at their operating contacts.
Cut from the centre outward
Switch to PDC and inspect the underside. One blade reaches the drill axis; the others begin farther out. Follow the fixed cutter faces toward the shoulder. An outer cutter travels farther in one revolution than an inner cutter, although both complete the same turn.
Clear the cutting face
In the assembled view, show the nozzle paths and rock reference. Trace the route from each outlet toward the face, then outward between the cutting structures. The fluid route and rock surface are visual guides; this model does not remove rock or calculate a drilling rate.
The main parts
- Threaded shank and body
- The male threaded pin connects the bit to the drillstring. The body carries the cutting structure, while the central opening leads into the internal fluid space. The thread shape is illustrative, not a specified connection.
- Carbide inserts and cones
- Three conical steel shells carry staggered rows of rounded tungsten-carbide inserts. Each cone rotates around its own inclined journal as the body turns.
- Cone journals
- Each forged leg supports an inward-tilted journal. Separate the assembly to expose the shaft and thrust shoulder. The internal bearing and lubrication system are not sectioned.
- Curved blades and gauge pads
- Six swept blades support the fixed cutters. Channels between them, called junk slots, leave room for fluid and cuttings to move away from the face. The outer gauge pads mark the full-diameter region.
- Fixed diamond cutters
- The dark diamond face sits on a carbide support in each blade. Follow the cutter row from the centre-reaching blade toward the outer shoulder: the faces point into their circular paths and stay fixed in their seats.
- Reference rock plane
- The optional transparent plane locates the approximate cutting envelope. The concentric marks are guides, not a prediction of the hole-bottom pattern. No rock is removed in this model.
- Drilling-fluid nozzles
- Fluid reaches the outlets through the bit body. The open nozzles aim toward the cutting region; blue traces indicate cleaning flow across the face and out through the gaps. They show a route, not calculated pressure, flow rate or cuttings transport.
Questions worth exploring
Do the individual PDC cutters spin?
The conventional cutters shown here stay fixed in their blade seats. The whole bit rotates, so each cutter follows a circular path around the drill axis without turning independently in its seat. Compare that with a tricone: each cone rotates on an inclined journal as the bit body turns. The model deliberately slows both motions for inspection.
SLB Energy Glossary · PDC bit (fixed cutters and shearing)SLB Energy Glossary · Roller cone bitSLB · The Defining Series: Bits (roller cones, PDC blades and fluid paths)
Why does the cutting structure need to reach the centre?
A full-hole bit needs cutting structure near the axis as well as toward the wall; a coring bit instead leaves a central opening for a rock sample. Inspect the centre-reaching PDC blade, then follow the staggered cutters outward. Circular travel is 2πr per turn, so inner cutters travel less far and a point exactly on the axis has no tangential travel. Centre coverage alone does not prove rock removal; fracture and penetration are not simulated here.
SLB · The Defining Series: Bits (roller cones, PDC blades and fluid paths)
What do the fluid nozzles do?
Nozzles let drilling fluid exit the bit toward its cutting region. The jets help clear the bit and hole bottom; flow can then carry cuttings away. On a PDC bit, the gaps between blades provide outward routes. Turn on the blue traces to inspect the illustrated route. Their speed and thickness are visual choices, not measurements of fluid pressure or cleaning performance.
SLB Energy Glossary · Jet nozzle (fluid outlets and cleaning)SLB · The Defining Series: Bits (roller cones, PDC blades and fluid paths)