PDC（Polycrystalline Diamond Compact ) cutter bit inserts are sintered with selected diamond powder and tungsten carbide under high temperature and ultra-high pressure.
PDC’s have high hardness, wear resistance and impact resistance, are widely used for oil/gas well drill bit, rock drill and coal mining bitalso could be used for diamond tools for cutting, grinding, polishing.
As a general rule, large cutters (19mm to 25mm) are more aggressive than small cutters. However, they may increase torque fluctuations.
Smaller cutters (8mm, 10mm, 13mm and 16mm) have been shown to drill at higher ROP than large cutters in certain applications. One such application is limestone for example.
Additionally, small cutters produce smaller cuttings while large cutters produce larger cuttings. Large cuttings may cause problems with hole cleaning if the drilling fluid cannot carry the cuttings up.
(1) or (2) Soft and soft sticky-Highly drillable formations such as clay, marl, gumbo and unconsolidated sands.
(3) Soft-medium-Low compressive strength sands, shale and anhydrites with hard layers intermixed.
(4) Medium-Moderate compressive strength sand, chalk, anhydrite and shale.
(6) Medium hard-Higher compressive strength with non-or semi-sharp sand, shale, lime and anhydrite.
(7) Hard-High compressive strength with sharp layers of sand or siltstone.
(8) Extremely hard-Dense and sharp formations such as quartzite and volcanic rock.
PDC CUTTING STRUCTURE
Very soft (1) to medium (4) formation type pdc bits have one dominant size of PDC cutter. PDC cutting structure is denoted in the following way:
2 – this bit has mostly 19mm cutters
3 – this bit has mostly 13 mm cutters
4 – this bit has mostly 8 mm cutters