China Tungsten Drill Bit Manufacturer & Manufacturers

Carbide drill button breakout is typically caused by two distinct metallurgical failures: fatigue micro-cracking along brittle grain boundaries and internal voids acting as stress risers. By utilizing coarse WC grains (3.0 to 4.5 μm) bonded with 10%–12% Cobalt and processed under 60-bar overpressure Sinter-HIP conditions, internal porosity is virtually eliminated (porosity rating < A02, B00). This achieves a high Transverse Rupture Strength (TRS > 2,800 MPa) combined with exceptional fracture toughness (K1C > 14.5 MPa·m½), effectively deflecting shock shockwaves encountered when striking hard quartz seams.

Cemented tungsten carbide shrinks volumetrically by approximately 18% to 22% during thermal liquid-phase sintering. We utilize high-precision CNC multi-axis hydraulic powder compacting presses with proprietary closed-loop punch velocity control. Die cavity designs incorporate finite-element shrinkage modeling based on the specific lot powder surface area (BET value). For critical mounting diameters, centerless and cylindrical grinding delivers h6 tolerance (within +0.000 / -0.009 mm), ensuring snug press-fit or brazing gap precision into steel bit bodies.

Low-grade scrap reclamation often introduces uncontrolled interstitial tramp elements like iron, nickel, calcium, and phosphorus. These impurities promote the development of the brittle carbon-deficient eta-phase (Co3W3C or Co6W6C) during sintering, precipitating catastrophic brittle fracture under low impact loads. Zhongfu uses 100% virgin tungsten powder synthesized directly from refined ammonium paratungstate (APT), yielding pristine crystal boundaries, uniform cobalt distribution, and repeatable hardness-to-toughness ratios across high-volume production batches.

Tungsten carbide and structural steel possess vastly different thermal expansion coefficients (Carbide: 5.0 × 10⁻⁶/K vs. Steel: 12.0 × 10⁻⁶/K). Direct cooling generates massive residual tensile stress at the brazed seam. We advise using silver-copper-nickel sandwich tri-foil braze fillers (such as Ag49MnNi / BAg-22) with active fluoride-free fluxes. Induction brazing should maintain temperatures between 680°C and 720°C, followed by slow cooling in vermiculite or temperature-controlled annealing ovens to relieve interfacial shear strain.

Yes. Traditional cobalt-bonded tungsten carbide is ferromagnetic and causes severe azimuth reading distortion when situated near magnetic survey probes in MWD/LWD string assemblies. We formulate our ZF-NM series by substituting cobalt with a pure nickel-chromium austenitic binder. This yields high Vickers hardness (1,450 – 1,600 HV30), excellent resistance to chloride-induced pitting corrosion, and a relative magnetic permeability (μr) consistently below 1.002.

Standard stocked geometries (including standard round rods, square blocks, and SPUB scarfing inserts) ship within 48 to 72 hours. Custom tool drawings requiring new carbide compacting die sets typically require 12 to 15 working days for die development, test pressing, Sinter-HIP firing, and coordinate measurement inspection. International shipments are packed in rust-inhibiting VCI film, secured in reinforced multi-layer cartons and export plywood crates, and dispatched via DDP/FOB air freight or ocean logistics.