Tungsten carbide balls production primarily involves powder metallurgy, combined with high-precision machining and heat treatment techniques. The following are the key production steps and methods:
1. Raw Material Preparation and Powder Preparation:
Raw Material Selection: Tungsten carbide balls primarily consist of tungsten carbide (WC) and a binder such as cobalt (Co). Titanium carbide (TiC) or tantalum carbide (TaC) are sometimes added to enhance performance.
Powder Mixing: Carbide powder and binder powder are mixed using a high-energy ball mill to ensure uniformity. The particle size distribution must be controlled during mixing, typically within the nanometer or submicron range.
Granulation: The mixed powder is granulated using techniques such as spray drying to facilitate subsequent forming.
2. Forming Technology:
Compression Forming: Cold isostatic pressing (CIP) or die pressing is used to press the powder into spherical blanks. Cold isostatic pressing ensures uniform billet density and reduces internal defects.
Injection Molding: For complex shapes or small balls, metal injection molding (MIM) can be used, where the powder is mixed with a binder and then injection molded.
3. Sintering Process:
Vacuum Sintering: High-temperature sintering (typically 1300-1500°C) is performed in a vacuum or low-pressure environment to bond the powder particles and form a dense carbide structure.
Hot Isostatic Pressing (HIP): After sintering, hot isostatic pressing (HIP) is used to further eliminate internal porosity and increase material density and strength.
Atmosphere Control: The atmosphere (such as hydrogen or inert gas) must be strictly controlled during the sintering process to prevent oxidation and maintain material properties.
4. Precision Machining:
Grinding and Polishing: After sintering, the tungsten carbide balls billet undergoes precision grinding and polishing to achieve high roundness and surface finish requirements. Diamond grinding wheels are typically used for this process.
Dimensional Control: High-precision CNC equipment is used to ensure ball diameter tolerances within micrometers.
5. Surface Treatment:
Coating Technology: Some tungsten carbide balls are coated with PVD (physical vapor deposition) or CVD (chemical vapor deposition) coatings, such as TiN and TiAlN, to enhance wear and corrosion resistance.
Ultra-Precision Polishing: Chemical Mechanical Polishing (CMP) is used to further improve surface quality and reduce the coefficient of friction.
6. Quality Inspection:
Dimensional and Roundness Inspection: High-precision measuring instruments (such as laser micrometers and roundness gauges) are used to inspect the dimensional accuracy and geometric shape of the balls.
Performance Testing: This includes hardness (HRA or HV), density, compressive strength, and microstructure analysis to ensure product compliance.
Non-Destructive Testing: Ultrasonic or X-ray testing is used to detect internal defects.
7. Process Optimization and Innovation:
Nanotechnology: Nano-sized powders and advanced sintering technologies (such as spark plasma sintering) are used to improve material toughness and strength.
Automated Production: Automated production lines and robotics are introduced to improve production efficiency and consistency. Green Manufacturing: Optimize process flow to reduce energy consumption and waste emissions, such as recycling cobalt and tungsten carbide powder.
