Silica Sol vs. Water Glass Investment Casting: Key Differences & Advantages

1. Silica Sol Investment Casting (Colloidal Silica Binder)

Advantages:
✔ Higher Precision – Tolerances up to CT4-6 (ISO 8062) for complex geometries.
✔ Smoother Surface Finish – Ra 1.6-3.2 μm, reducing post-machining needs.
✔ Better Shell Strength – Fewer defects (e.g., cracks, veining) due to nano-scale silica particles.
✔ Superior Alloy Compatibility – Ideal for high-performance alloys (e.g., stainless steel, superalloys).

Limitations:
➞ Higher cost (20-30% more than water glass).
➞ Longer production cycle (additional drying steps).

2. Water Glass Investment Casting (Sodium Silicate Binder)

Advantages:
✔ Lower Cost – 40-50% cheaper binder materials.
✔ Faster Production – Single-step hardening with CO₂/NH₄Cl reduces cycle time.
✔ Adequate for Simpler Parts – Suitable for carbon steels and non-critical components (tolerance CT7-9).

Limitations:
➞ Rougher surface (Ra 6.3-12.5 μm) requiring more post-cast machining.
➞ Prone to “frosting” defects and lower high-temperature stability.

Head-to-Head Summary