The IADC classification system, developed by the International Association of Drilling Contractors has been the representative voice of drillers worldwide since 1940. This system of roller cone identification was established in 1987 and expanded in 1992 to include more features.
The following is an example of standard roller cone nomenclature:
The first digit actually denotes two different things:(1) Tooth or button
The second digit indicates formation hardness the bit was designed to drill.
The third digit indicates bearing type. For a more in-depth discussion of bearing types, click here.
The fourth digit is a letter code indicating certain characteristics:A - Air Application
FOR ROCK HARDNESS
IADC DULL GRADING
An eight point dull grading system has been established by the IADC to enable drillers and bit manufacturers evaluate the performance of a drill bit. This eight point system is described below and is used on both tricones and fixed cutter bits:
1. Inner Cutting Structure - Inner cutting structure wear is also noted by a number ranging from 0 to 8 with 0 being no wear and 8 being total wear.
2. Outer Cutting Structure - Outer cutting structure wear is also denoted by a number ranging from 0 to 8 with 0 being no wear and 8 being total wear.
3. Dull Characteristics - Dull characteristics enables the bit salesperson or driller to determine the overall, distinctive aspect of the dulled drill bit according to IADC standards as follows:
4. Location - Location describes where the damage is on the cone. N - Nose Row; M - Middle Row; G - Gauge Row; A - All Rows
Cone Number One contains the centermost cutting component. Cones two and three follow in a clockwise manner.
Nose row is the centermost cutting structure.
Gauge row is the outer most cutting structure.
5. Bearings/Seals - For open or roller bearing bits, bearing life is estimated on a scale of 0 to 8. Zero equals complete bearing intact, eight equals no bearing life left. "X" indicates fixed cutter.
If the drill bit has a sealed bearing, an "E" indicates the seals are effective or "F" is used to indicate failed seals.
6. Gauge - Gauge measures the amount of gauge wear a drill bit has suffered. 1=1/16" out of gauge; 2=1/8" out of gauge; 4=1/4" out of gauge.
7. Other Dull Characteristics - Any other dull grading characteristics should be noted here using the codes from #3.
8. Reason Pulled - The following codes are used to indicate the reason a bit was pulled from the hole:
BC - Broken Cone
BU - Balled Up
CD - Cone Drag
CR - Cored
ER - Erosion
HC - Heat Checking
LC - Lost Cone
LT - Lost Teeth
NR - Not Rerunnable
PB - Pinched Bit
RG - Rounded Gauge
SD - Shirttail Damage
TR - Tracking
WT - Worn Teeth
BT - Broken Teeth
CC - Cracked Cone
CI - Cone Interference
CT - Chipped Teeth
FC - Flat Crested Wear
JD - Junk Damage
LN - Lost Nozzle
NO - No Dull Characteristics
OC - Off Center Wear
PN - Plugged Nozzle
RR - Rerunnable
SS - Self Sharpening Wear
WO - Washed Out
BHA - Change Bottom Hole Assembly
CP - Core Point
DP - Drill Plug
DST - Drill String Test
DST - Drill String Test
HR - Hours on Bit
LOG - Run Logs
PR - Penetration Rate
TD - Total Depth/Casing Point
TW - Twist Off
WO - Washout
CM - Condition Mud
DMF - Downhole Motor Failure
DSF - Drill String Failure
DTF - Downhole Tool Failure
HP - Hole Problems
LIH - Left in Hole
PP - Pump Pressure
PP - Pump Pressure
TQ - Torque
RIG - Rig Repair
WC - Weather Conditions
API Standards: API standards, including pin sizes for drill bits and acceptable tolerances for rock bits and pdc bits.
Atlas Copco: Atlas Copco bit selection guide, examples of shirttail protection, and TCI and steel tooth cutting structure.
Button Bits: Button bits offer several advantages over PDC drill bits: they are less expensive and can withstand higher impact.
Drag Bits: Drag Bits manufactured as one solid piece of alloy steel offer greater durability and reliability. Available in step and chevron styles for hard rock drilling.
Dull Grading: Dull grading drill bits is important but often overlooked. This process provides valuable information for proper bit selection.
IADC: The IADC classification system for tooth and button bits explained as well as dull grading codes and what they mean.
IADC Classification: The IADC classification system for PDC bits: pictures and explanation of what it means and how to use it.
PDC Cutters: Because of PDC cutters, PDC bits drill sixty-five percent of total footage. Their shearing action is more efficient than the crushing action of tricones.
PDC Drill Bits: Available in either matrix or steel bodies, PDC drill bits offer higher rate of penetration than tricones in many different formations.
Tricones: With the exception of cutting structure, tricone bits are designed in the same manner regardless of manufacturer.
Well Completion Bits: Well completion drill bits from Atlas Copco in both tooth and button bits. Bear Claw, Hurricane, Aardvark, and PDC diamond mill bits from KC Bit & Supply.