When you need more precision than sand casting, but your budget cannot handle high-end investment casting, choose the sodium silicate casting process. It combines good precision with low cost. It is the ideal choice for many small to medium batch steel, iron, and copper alloy castings.
Sodium silicate casting is one of the specialty processes at QD Foundry. We are committed to helping you strike the optimal balance between precision and cost.
What Is Sodium Silicate Casting？
Sodium silicate casting is also known as water glass casting. It is a precision casting method. It uses sodium silicate solution as a binder. It can be considered a more economical version of investment casting. This is because its material cost and process complexity are relatively low. At the same time, it provides better precision and surface quality than ordinary sand casting.
Introduction to QD’s Sodium Silicate Casting Process
The basic steps of sodium silicate casting include:
- Pattern Making: First, create wax patterns or foam patterns based on part drawings.
- Coating: Mix sodium silicate solution with refractory materials (like quartz sand). Coat the mixture onto the pattern surface to form the shell mold.
- Curing: Harden the shell mold using carbon dioxide gas or natural drying.
- Mold Removal & Pouring: Remove the pattern, then pour molten metal into the shell mold. The casting is obtained after cooling.
- Post-Processing: Includes cleaning, heat treatment, and machining. This ensures the casting meets requirements.
This process is particularly suitable for small to medium batch production.
Core Advantages
Sodium silicate casting offers significant advantages in cost, precision, and material adaptability. Below is a detailed analysis of its core strengths:
Cost Advantage
Sodium silicate works as the binder. Its material cost is much lower than silica sol, which is commonly used in investment casting. Furthermore, the required equipment investment and energy consumption are relatively low. This makes the overall production cost more competitive.
| Item | Sand Casting | Sodium Silicate Casting | Investment Casting |
| Material Cost | Low | Medium | High |
| Equipment Investment | Low | Medium | High |
| Per Piece Cost (Small/Medium Batch) | Lowest | Lower | High |
| Suitable Batch Range | Large Batches | Small/Medium Batches | Small Batches |
Precision and Surface Quality
Sodium silicate casting typically achieves dimensional accuracy of CT7-CT9. Surface roughness can reach Ra 12.5-25 μm. This is significantly better than sand casting (CT10-CT13, Ra 25-100 μm). While slightly lower than investment casting (CT4-CT6, Ra 3.2-12.5 μm), it sufficiently meets requirements for most applications.
Material Adaptability
Sodium silicate casting is particularly suitable for the following materials:
Carbon and Alloy Steels: Such as 45 steel and 40Cr. Widely used for mechanical structural components.
Cast Iron: Including gray iron and ductile iron. Used for wear-resistant parts.
Copper Alloys: Such as bronze and brass. Commonly used for valves and hardware components.
These materials offer good fluidity during the casting process. They have high compatibility with the sodium silicate mold shells. This helps minimize defects effectively.
Production Flexibility
Sodium silicate casting supports small to medium batch production (dozens to thousands of pieces). It has short lead times. Mold modifications are easy to implement. It is highly suitable for new product development or customized needs. In comparison, sand casting suits high-volume production but has limited precision. Investment casting offers high accuracy, but its cost restricts batch flexibility.
Typical Applications
Sodium silicate casting is widely used across multiple industries due to its balanced performance. Here are its typical application fields:
Hardware Tools: Such as wrenches, pliers, and other hand tools. They require certain precision and durability.
Pipe & Valve Fittings: Including flanges, joints, etc. They need pressure resistance and sealing properties.
Mechanical Parts: Such as gears, bearing housings, brackets, and other structural components.
Auto Parts: For example, brake components, engine brackets. They balance strength and cost.
Agricultural Machinery Parts: Like plowshares, harvester components. Often made from cast iron or steel.
Artware & Architectural Hardware: Decorative pieces with complex shapes. Achieve aesthetic effects through post-processing.
QD has provided sodium silicate casting solutions for hundreds of clients. We have accumulated extensive industry experience.
Limitations of Sodium Silicate Casting
While sodium silicate casting has clear advantages, it also has some limitations. Customers should consider these factors when making a choice:
Surface Quality and Precision Limits: Compared to the silica sol process, the castings may be slightly rougher. Dimensional accuracy is somewhat lower. It usually does not suit parts with extremely high precision requirements. However, QD offers surface treatment services, including polishing.
Mold Shell Strength: The shell may soften at high temperatures. We must strictly control process parameters to prevent deformation.
Environmental and Post-Processing: The binder may produce alkaline wastewater during shell removal. This requires treatment facilities. QD has optimized the process and uses a circulation system to minimize environmental impact.
Material Limitations: It is less suitable for high-melting-point or special alloys (like titanium alloys).
The QD team provides a detailed assessment early in the project. This ensures the process is a good match for your needs.
Why Choose QD Foundry?
When selecting a casting process, the supplier’s expertise and service are as crucial as technical parameters. QD offers unique advantages in sodium silicate casting:
Extensive Experience: We have over 20 years of practical experience. Our services cover tools, machinery, automotive, and other industries.
Quality Control: We monitor the entire process. From raw materials to finished products. We ensure castings meet GB, ISO, and other standards.
Customized Service: We adjust processes based on client needs. We provide one-stop solutions from design optimization to post-processing.
Rapid Response: With our efficient team, we can provide initial feedback on drawing evaluations within 24 hours.
Cost Control: Through bulk purchasing and process optimization, we help reduce total costs without sacrificing quality.
We believe sodium silicate casting is not just a process choice, but a strategy for maximizing value. By partnering with us, you benefit from both reliable technology and supportive service.
Contact Us
Seeking the perfect balance between precision and cost? Sodium silicate casting is one of our specialty services. Send us your part drawings. Let us evaluate its suitability for this process.
FAQ
1. What is the typical accuracy of sodium silicate casting?
Dimensional accuracy typically reaches CT7-CT9. Surface roughness is Ra 12.5-25 μm. Specific results depend on part design and material.
2. Is it suitable for small-batch production?
Yes. It is very suitable for small to medium batches (dozens to thousands of pieces). Mold costs are low. Production cycles are short.
3. Which materials are most suitable for this process?
Carbon steel, alloy steel, cast iron, and copper alloys are the best choices. High-melting-point or special alloys require further evaluation.
4. How much post-processing do the castings require?
This typically includes cleaning, polishing, and necessary machining. We can provide customized post-processing services according to your requirements.
5. What is QD’s lead time for sodium silicate casting?
For small/medium batches, it is generally 15-30 days. The exact time depends on complexity and quantity. We prioritize fast delivery.
6. How to determine if my part is suitable for this process?
Please provide the part drawing or 3D model. Our engineers will conduct a free assessment based on material, structure, and accuracy requirements.