‌Tungsten Carbide Solid Rod Manufacturing Process

Tungsten carbide solid rods are critical components in machining, mining, and precision engineering due to their exceptional hardness and wear resistance. Their manufacturing process is a precise, multi-step sequence that balances material properties with dimensional accuracy, ensuring the final product meets industrial standards.

1. Raw Material Preparation

The core materials are tungsten carbide (WC) powder and cobalt (Co) powder—cobalt acts as a binder to hold WC grains together. WC powder typically has a particle size of 0.5–5 μm, as finer particles enhance the rod’s density and hardness. The cobalt content (usually 6–12% by weight) is carefully controlled: higher cobalt improves toughness but reduces hardness, while lower cobalt boosts wear resistance but increases brittleness. Both powders are screened to remove impurities like oxides or clumps, which could cause defects in the final rod.

2. Mixing and Granulation

The prepared WC and Co powders are mixed in a wet mixing process using a solvent (e.g., ethanol or acetone) and a dispersant. This ensures uniform distribution of cobalt around WC grains—critical for consistent mechanical properties. The mixture is then dried to remove the solvent, forming a fine, free-flowing powder. For better compaction, the dried powder is often granulated into small pellets (100–300 μm), which improves powder flow during the next step.

3. Compaction

The granulated powder is pressed into a green compact (a porous preform) using cold isostatic pressing (CIP)—the most common method for solid rods. The powder is loaded into a flexible rubber mold, and high pressure (150–300 MPa) is applied uniformly from all directions. This creates a green rod with a density of ~50–60% of the final product, preserving the rod’s cylindrical shape and preventing cracks from uneven pressure.

4. Sintering

Sintering is the key step that transforms the green compact into a dense, hard rod. The green rods are placed in a vacuum or inert gas (argon) furnace and heated to 1350–1500°C for 1–4 hours. At this temperature, cobalt melts and flows, bonding WC grains together (a process called liquid-phase sintering). The rod shrinks by ~15–20% and reaches a final density of >98% of the theoretical density. Slow cooling after sintering minimizes internal stresses.

5. Post-Processing and Quality Control

After sintering, rods undergo precision grinding (using diamond wheels) to achieve tight dimensional tolerances (±0.01 mm) and a smooth surface finish. Some applications require additional machining, such as drilling or threading. Finally, quality control includes testing hardness (typically 85–95 HRA), density, and microstructure to ensure compliance with industry standards.