tin tức công ty về Common Nozzle Sizes for Diamond Bits and Application References

Diamond bits are core tools for hard rock drilling and high-precision coring, widely used in scenarios such as hard rock mining of metal ores, ultra-deep oil & gas well drilling, and geological exploration coring. Their nozzles (also known as "water eyes") are key components ensuring drilling efficiency and bit service life. The core functions of nozzles include injecting high-pressure drilling fluid to cool the diamond cutting layer, flush hard rock cuttings, and assist rock breaking. Although diamonds have extremely high hardness, their heat resistance is limited (long-term operating temperature must be controlled below 700℃), and hard rock cuttings are highly abrasive. The rationality of nozzle size (primarily inner diameter, outer diameter, and connection method) directly affects operational performance: a too-small size leads to insufficient drilling fluid flow, causing overheating wear of the cutting layer and cuttings accumulation; a too-large size results in pressure loss, weakening rock-breaking impact force. This article uses plain language and clear tables to sort out common nozzle size specifications, selection criteria, and typical application scenarios for diamond bits, helping industry practitioners quickly match bit models with nozzle sizes and improve the stability and economy of hard rock drilling.

Before exploring sizes, let’s briefly sort out the core value of nozzles to understand "why size selection cannot be ignored":

1. Precision Cooling: Friction between the diamond cutting layer (natural or synthetic diamond) and hard rock (such as granite and basalt) generates significant heat. High-pressure drilling fluid is precisely injected onto the cutting surface through nozzles to quickly dissipate heat, preventing the diamond layer from falling off or carbonizing due to overheating;
2. Efficient Cuttings Removal: Hard rock cuttings are hard and highly abrasive. If accumulated on the bit working surface, they will accelerate diamond wear. High-speed injected drilling fluid can promptly flush cuttings to the ground, reducing repeated grinding;
3. Assisted Rock Breaking: High-pressure drilling fluid forms jets through nozzles of specific sizes to pre-etch fractures on the hard rock surface, reducing the cutting resistance of diamonds and improving hard rock breaking efficiency.

The mainstream material of diamond bit nozzles is high-end tungsten carbide cemented carbide (some use diamond-reinforced tungsten carbide), featuring ultra-high hardness (HRA≥91), wear resistance, and pressure resistance. It can withstand the erosion of high-pressure drilling fluid (30-60MPa), with a service life 8-12 times that of ordinary metal nozzles, perfectly adapting to the high-frequency and high-load operational needs of diamond bits in hard rock working conditions.

Nozzle size marking for diamond bits is centered on "inner diameter (imperial/metric) + connection method". The outer diameter and length need to match the nozzle mounting holes of the bit (complying with API standards or manufacturer-customized specifications). Below are the most commonly used size specifications in the industry, covering the adaptation needs of mainstream 6-17½ inch diamond bits, with a focus on balancing pressure and flow in hard rock drilling:

1. Size marking logic: The industry prioritizes imperial units (inches) to align with international general standards for diamond bits (e.g., API 7-1). Metric units are for conversion reference, facilitating use in non-imperial unit regions;
2. Connection method: Threaded connections account for over 95%, with NC50 as the mainstream specification, adapting to most medium and large diamond bits; flange connections are only used for extra-large diameter nozzles or extreme high-pressure working conditions (pressure ≥50MPa) to ensure connection tightness and pressure resistance;
3. Non-standard sizes: For micro diamond bits (≤6 inches) or precise pressure-controlled coring scenarios, non-standard nozzles with inner diameters of 5-7mm (corresponding to 4/32"-9/32") can be customized to meet personalized needs.

Selecting diamond bit nozzle sizes requires no complex calculations. Focus on the following 3 points for quick demand matching:

Nozzle size is positively correlated with bit diameter: the larger the bit diameter, the greater the required drilling fluid coverage area and flow, and the larger the corresponding nozzle inner diameter. For example: A 9⅞-inch (250.8mm) diamond bit is usually paired with a nozzle with an inner diameter of 11/32"-13/32". Using a small 9/32" nozzle will result in insufficient drilling fluid coverage of the entire cutting layer, local overheating wear, and cuttings accumulation leading to sticking.

Diamond bits are only suitable for hard rock formations. Different types of hard rock have slightly different requirements for nozzle sizes:

• Dense hard rock (e.g., granite, basalt): High-pressure jets are needed to assist rock breaking. It is recommended to select a medium-sized nozzle (e.g., 11/32"-13/32") to reduce pressure loss and maximize jet impact force;
• Siliceous hard rock (e.g., siliceous shale, quartz sandstone): Cuttings are highly abrasive, requiring large-flow rapid cuttings removal. A slightly larger nozzle can be selected (e.g., 13/32" instead of 11/32") to avoid cuttings wearing the diamond layer;
• Fracture-developed hard rock: A balance between cooling and anti-sticking is required. Prioritize a medium size (e.g., 13/32") to ensure a balance between flow and pressure, preventing cuttings accumulation in fractures.

Nozzle size must match the rated flow rate and pressure of the drilling pump:

• Large drilling pump flow rate (≥25L/s): Select a large-sized nozzle (e.g., 15/32"-17/32") to avoid excessive system pressure due to flow restriction, which may damage the bit or pipeline;
• High drilling pump pressure (≥45MPa): Select a medium-sized nozzle (e.g., 11/32"-15/32") to ensure jet impact force and improve hard rock breaking efficiency;
• Industry experience formula: Nozzle inner diameter (inch) ≈ Bit diameter (inch) * 0.04-0.07 (e.g., 12¼-inch bit * 0.05 ≈ 13/32-inch nozzle).

1. Size Consistency: Multiple nozzles (usually 2-4) on the same diamond bit must be of the same size to avoid unbalanced force on the cutting layer, bit wear, or trajectory deviation due to uneven flow;
2. Material Adaptation: Prioritize high-end tungsten carbide cemented carbide nozzles, especially in highly abrasive hard rock, to avoid frequent replacement of ordinary metal nozzles due to rapid wear, which affects operational efficiency;
3. Installation Inspection: Clean debris (such as cuttings and oil) from the nozzle inner diameter before installation, check thread/flange tightness, and test drilling fluid pressure after installation (fluctuation ≤5MPa is normal);
4. Regular Replacement: When the nozzle inner diameter wears more than 10% of the original size (e.g., a 13/32" nozzle with a worn inner diameter ≥11mm), or erosion pits/cracks appear, replace it in a timely manner to avoid affecting cooling and rock-breaking effects.

Selecting diamond bit nozzle sizes requires no complex professional knowledge. The core is to match "bit diameter + formation characteristics + drilling fluid parameters": choose medium sizes for dense hard rock, medium-to-large sizes for highly abrasive hard rock, and small sizes for small-diameter bits and precise coring. The common size table compiled in this article can be directly used as a quick reference for purchasing and replacing nozzles, covering over 90% of hard rock drilling scenarios.

As a tungsten carbide industry practitioner, we can provide full-specification diamond bit nozzles (from 9/32" to 19/32" and non-standard customization), made of high-end YG6X/YG8 tungsten carbide to ensure ultra-high wear resistance and pressure resistance. If you need to recommend precise sizes based on specific diamond bit models, drilling formations, or equipment parameters, please contact us for customized solutions to help improve hard rock drilling efficiency and reduce operation and maintenance costs.