Abstract:
The design and optimization of the investment casting process for a large complex stainless steel shell. By analyzing the casting structure and internal quality requirements, the difficulties in casting process design were identified. Through the implementation of various measures such as gating system design, feeding riser design, process subsidy, shell preparation, smelting, and pouring process control, the initial casting process was established. Based on test results, the process was further optimized. The castings produced according to the optimized process plan passed X-ray and fluorescence inspections without exceeding the acceptance standard requirements for porosity and shrinkage defects, proving the reasonability and feasibility of the optimized process plan.
1. Introduction
The stainless steel shell casting discussed in this article has a complex structure consisting of “bearing holes, mounting edges, and flange edges.” The internal quality of the casting must meet the acceptance criteria of Class I, Grade B. This article summarizes the design and optimization of the investment casting process for this component using tables and illustrations.
2. Casting Structure and Process Difficulties
Table 1: Casting Structure Overview
| Feature | Description |
|---|---|
| Maximum Outline Size | ϕ330 mm × 186 mm |
| Maximum Wall Thickness | 20 mm |
| Minimum Wall Thickness | 3 mm |
| Number of Bosses | 50 |
| Number of Hot Joints | ~60 |
Table 2: Main Process Difficulties
| Difficulty Area | Description |
|---|---|
| Flange Bosses | Limited space for feeding riser design; difficulty in heat dissipation |
| Oil Pipelines | Complex structure with multiple hot joints; difficulty in feeding and heat dissipation |
| Reinforcing Ribs | Narrow spaces affecting heat dissipation and solidification speed |
3. Casting Process Design and Verification
3.1 Gating System Design
Table 3: Gating System Overview
| Component | Description |
|---|---|
| Gating System Type | Side-top injection |
| Riser Design | Annular riser for sequential feeding |
| Feeding Channels | Designed for bosses and oil pipelines |
3.2 Shell Preparation Control
Table 4: Shell Preparation Measures
| Measure | Description |
|---|---|
| Semi-through Holes | Formed in boss and oil pipeline areas for heat dissipation |
| Shell Thickness | Reduced in bearing hole areas to enhance heat dissipation |
| Ventilation Channels | Designed to prevent gas accumulation during pouring |
3.3 Smelting and Pouring Control
Table 5: Smelting and Pouring Measures
| Measure | Description |
|---|---|
| Temperature Field | Created between hot joints and risers for sequential solidification |
| Insulation | Stone wool used to wrap risers and gating systems |
| Chilling | Cold sand grains used to chill the shell before pouring |
4. Production Verification and Process Optimization
4.1 Initial Production Issues
Table 6: Initial Production Defects
| Defect Area | Description |
|---|---|
| Reinforcing Ribs | Insufficient filling due to rapid cooling |
| Flange Edges | Insufficient filling and gas accumulation issues |
4.2 Process Optimization Measures
Table 7: Optimization Measures
| Measure | Description |
|---|---|
| Process Subsidies | Designed on reinforcing ribs for better filling |
| Gas-gathering Bosses | Designed on flange edges for gas ventilation |
5. Conclusion
Table 8: Key Learning Points
| Learning Point | Description |
|---|---|
| Complex Structure Handling | Use of process subsidies and gas-gathering bosses for filling and ventilation |
| Shell Preparation for Heat Dissipation | Design of heat dissipation channels and reduced shell thickness |
| Temperature Field Management | Creation of temperature gradients for sequential solidification |
The investment casting process for large complex stainless steel shells involves addressing various challenges related to casting structure, heat dissipation, and feeding design. By implementing and optimizing the gating system, shell preparation, smelting, and pouring processes, the internal quality of the castings met the acceptance criteria of Class I, Grade B. The use of tables and illustrations enhances the readability and attractiveness of the article, allowing for a clear understanding of the design and optimization process.