Drilling equipment & exploration services
长坤地质 CHANGKUN GEO

CORE DRILLING TOOLS

Diamond core bits

Diamond core bits

Diamond core bits in NQ, HQ and PQ sizes are selected with the barrel and reaming shell. Matrix selection considers rock hardness, grain size, fracturing and rig conditions within the listed K1 to K11 grades. Specify the size series, matrix grade and quantity when ordering.

NQ / HQ / PQ

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Product overview

Annular cutting leaves the core intact

A diamond core bit cuts an annulus, leaving a central core that enters the inner tube. Outside diameter relates to the hole; inside diameter relates to the core. For example, the NQ standard size is 75.3 × 47.6 mm, not two alternative hole diameters.

Matrix grade is one part of selection

Matrix grades include K1, K3, K5, K7, K9 and K11. Rig capability and actual drilling feedback also inform the choice. Share a formation description, the current bit model and observations on penetration or wear to help the team check the grade and size.

Match the shell and core barrel

An enquiry can check the reaming shell, tubes and other core tooling alongside the bit. Specify size series, matrix grade and quantity separately. If the existing tooling model is unclear, provide markings and connection photographs rather than relying on appearance alone.

    Technical data and sizes

    Bit dimensions and matrix configuration

    Swipe horizontally on small screens to see all data.

    ModelOD × ID mmCrown height codesListed matrix grades
    NQ75.3 × 47.6C9 / C12K3 / K5 / K7 / K9
    HQ95.6 × 63.5C9 / C12K3 / K5 / K7 / K9
    PQ122.0 × 85.0C9 / C12K3 / K5 / K7 / K9

    Drilling reference values

    Swipe horizontally on small screens to see all data.

    ModelFlow L/minReference speed rpmBit load kN
    NQ45–851,350 / 80014–27
    HQ50–1001,000 / 60018–36
    PQ60–120800 / 50023–45

    These reference values are not fixed operating settings for every rig; adjust for ground and rig capability.

    Size standardsNQ / HQ / PQ
    Matrix gradesK1 / K3 / K5 / K7 / K9 / K11
    Matching toolsReaming shells & wireline core tools

    Values are for equipment selection; supplied configurations follow the quotation and equipment documents.

    Selection questions

    Is a higher K matrix number always better?

    No. Match the matrix to hardness, abrasiveness, fracturing and rig conditions. The matrix range covers K1 to K11 overall, while the NQ, HQ and PQ standard table lists K3, K5, K7 and K9. The number is not a service-life ranking.

    Should the reaming shell be included?

    The bit and shell should have corresponding sizes. Whether to buy both depends on the existing models, condition and site requirements.