Fixed Cutter Bits
The fixed cutter bit (diamond, PDC, TSP ) classification system was introduced by the IADC in 1987. The system is comprised of a four character classification code (Table 4) indicating a total of seven bit design features : Cutter type, Body material, Bit profile, Fluid discharge, Flow distribution, Cutter size, and Cutter density. These relate directly to the design features discussed in the previous sections. The four character code corresponds to the following :
Column 1 — Primary Cutter Type and Body Material
Five letters are used to describe the cutter type and body material, as shown in Table
3. The distinction of “Primary” is used because one diamond material type will often be used as the primary cutting structure whilst another is used as backup.
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Column 2 — Cross sectional Profile
The numbers 1 — 9 are used to define the bits’ cross sectional profile, according to the 3 x 3 chart shown in Table 4. The term profile is used here to describe the cross section of the cutter/bottom hole pattern. This distinction is made because the cutter/ bottom hole pattern may not be identical to the bit body profile.
Column 3 — Hydraulic Design
The numbers 1 — 9 in the third character of the system refers to the hydraulic design of the bit, according to the 3 x 3 chart in Table 4. This design is described by two components: the type of fluid outlet and the flow distribution.
Column 4 — Cutter Size and Placement Density
The numbers 1 — 9 in the fourth character of the system refers to the cutter size and placement density, according to the 3 x 3 matrix chart shown in Table 4.