Tricone Drill Bits

There are four digits code comprises for tricone drill bits(The fourth digit is the supplementary code, rarely used.).

The fisrt digit–drill bit type

1-3 indicates milled-tooth bits, 4-8 denotes insert-tooth bits, as illustrated below.

PS: let me explain the concepts regarding milling cutters and insert-type drills.

Milled teeth: it are machined directly onto the tricone body blank using milling processes, with the same material as the tricone body itself. Their tooth life and wear resistance are lower than alloy tooth. Even with surface hardening, their wear resistance is still lower, resulting in faster wear in hard or abrasive formations. But in suitable soft formations, their large tooth size and deep penetration enable relatively high mechanical drilling rates.

Without the cost of alloy inserts, they are comparatively less expensive.

Insert teeth: involve embedding carbide teeth into the tooth holes of the tricone bit. They offer high wear resistance and strength. The hardness and wear resistance of carbide teeth significantly surpass those of steel teeth, providing greater resistance to formation abrasion and impact. They deliver high rock-cutting efficiency in hard formations.

However, conventional inlaid teeth may exhibit relatively low bottomhole coverage in soft formations due to their sharp profile and smaller dimensions, potentially yielding lower drilling efficiency than milled-tooth bits. Novel wide-inlay technology aims to address this limitation. The use of carbide teeth and inlaying processes increases cost, but extended service life contributes to lower overall cost per use.

Compared to milling teeth, the cost is higher. The alloy contains tungsten raw materials, and currently, the price of tungsten raw materials in China is rising daily, so the price of tooth-tipped drill bits is also increasing accordingly. If required, it is advisable to purchase them as soon as possible, otherwise the cost will only get higher and higher, and the drilling expenses will become increasingly expensive. Shop Now

Different numbers and tooth profiles suit different formations:

The second digit–rock grade designation.

The strata are classified into four grades from softest to hardest: 1, 2, 3, and 4. The higher the number, the harder the stratum.

The third digit–drill bit structural feature code

1 to 7 indicate the drill bit bearing and diameter-maintaining features,

8 and 9 are reserved for future new-structure drill bits.

The forth digit–additional structural features of the drill bit: (rarely used)

This letter indicates characteristics not covered by the preceding three digits.
The IADC has currently defined 11 features:
A—Air cooling;
C—Centre nozzle;
D—Directional drilling;
E—Extended nozzle;
G—Additional borehole protection/drill body protection;
J—Jet deflection;
R—Reinforced weld (for percussion drilling);
S—Standard milled teeth;
X—Wedge-shaped insert teeth;
Y—Conical insert teeth;
Z—Other shaped insert teeth.
Where a drill may possess multiple additional structural features, a single primary feature symbol shall be selected to represent it.

For example: tricone drill bit 517 denotes an insert-toothed drill bit; suitable for soft formation drilling; featuring sliding, sealed bearings with bore protection functionality.

PDC Drill Bits

The IADC CODE for PDC drill bits comprises four digits.

The fisrt digit–drill bit body structure

‘M’: Matrix body
‘S’: Steel body
‘D’: Diamond body

The second digit–suitability for formation hardness

1: Very soft
2: Soft
3: Soft to medium
4: Medium
5: No code
6: Medium hard
7: Hard

The third digit–structure of the cutting teeth

The first four digits, corresponding to the hardness of the formation, represent the size of the PDC drill bit’s cutting teeth as 1, 2, 3, or 4 respectively.
The corresponding IADC classifications are:
1: Teeth larger than 19mm
2: 19mm teeth
3: 13mm teeth
4: 8mm teeth

(Some person interpret IADC PDC drill bit classification as follows:
1: Teeth larger than 19mm
2: Teeth between 19mm and 13mm (inclusive of 19mm)
3: Teeth between 13mm and 8mm (inclusive of 13mm)
4: Teeth less than or equal to 8mm
Under this classification, a 16mm tooth would be categorised as 2.)

The last three digits denoting the hardness of the corresponding formation are represented by 1, 2, 3 (omitting 4) to indicate the type of diamond drill bit. The corresponding International IADC classifications are:
1: Natural diamond
2: TSP (Thermally Stable Polycrystalline)
3: Combination diamond
The fifth digit is unused.

The forth digit–crown shape of the drill bit

1. Short fishtail
2. Short profile
3. Medium profile
4. Long profile

For example: M323 denotes a tyre structure suitable for medium-soft ground, featuring 19mm cutting teeth and a long crown shape.