1. Project Background
During mass production of an aluminum die casting component, the customer encountered a persistent quality issue in a die casting mold manufactured by another supplier:
- Severe shrinkage porosity at the M6 threaded boss near the gate area
- Defects concentrated at the root of the thread
- Affecting tapping quality and mechanical strength
- High rejection rate and unstable production
The customer engaged Raidy Mold to conduct a full technical analysis and implement an effective solution.
2. Defect Description
Key Observations:
- Local sink or internal voids at thread root
- Porosity detected by X-ray inspection
- Thread failure during tapping (stripping / chipping)
- Concentration in thick-section boss area
3. Root Cause Analysis (Raidy Mold Engineering Diagnosis)
Through systematic evaluation of die casting mold design, thermal behavior, and solidification characteristics, Raidy Mold identified the core issue as:
3.1 Severe Local Hot Spot (Thermal Imbalance)
- The M6 threaded boss is a thick mass concentration area
- Located near the gate → exposed to higher melt temperature
- Becomes the last solidification zone
Result:
Insufficient feeding during solidification → shrinkage porosity formation
3.2 Inefficient Cooling System Design
- Original cooling channel distance: ~30 mm from cavity surface
- No localized cooling enhancement at critical area
- Heat cannot be removed effectively
Result:
Localized overheating → delayed solidification → porosity
3.3 Structural Constraints of the Mold
- Direct deep drilling of cooling lines poses:
- Risk of steel cracking
- Reduced structural integrity
4. Raidy Mold Optimization Solution
4.1 Localized Cooling Enhancement (Core Solution)
Key Actions:
- Reduced cooling distance from 30 mm → 10 mm
- Introduced targeted cooling near M6 threaded boss
- Improved heat extraction efficiency
Technical Impact:
- Reduced local temperature
- Accelerated solidification
- Improved feeding conditions
（Solution based on the client’s situation）
4.2 Insert (Modular) Structure Design
To support aggressive cooling while ensuring mold safety:
- Implemented split insert design at critical zone
- Enabled deeper and closer cooling channels
- Optimized stress distribution
Benefits:
- Prevents mold cracking or failure
- Enhances durability
- Enables advanced thermal control
4.3 Thermal Balance Reconstruction (HPDC Core Logic)
Raidy Mold’s approach goes beyond cooling:
Re-engineering solidification sequence
- Eliminates hot spot dominance
- Promotes directional solidification
- Improves material density and integrity
5. Validation Results
Measured Improvements:
- ✅ Significant reduction in shrinkage porosity
- ✅ Improved thread machining success rate
- ✅ Better X-ray inspection results
- ✅ Enhanced structural density
Production Performance:
- Stable mass production achieved
- Reduced rejection rate
- No new defects (e.g., cracking or deformation)
6. Horizontal Deployment
Raidy Mold extended the solution beyond a single mold:
Standardization Across Multiple Tools:
- Thermal analysis applied to all thick sections
- Cooling design guidelines upgraded
- Insert strategy standardized for high-risk areas
Outcome:
- Consistent quality improvement across multiple molds
- Reduced maintenance and rework costs
- Improved overall production reliability
7. Raidy Mold Core Competence Demonstrated
This case illustrates how a structured engineering approach can effectively resolve shrinkage-related issues in high pressure die casting applications. Within this process, Raidy Mold carried out a detailed evaluation of thermal behavior, focusing on solidification conditions rather than relying solely on geometric adjustments.
Based on this understanding, the cooling system was selectively optimized, with localized enhancements introduced in critical areas to improve heat dissipation and reduce thermal concentration. In parallel, corresponding structural modifications were implemented to support the revised cooling layout, ensuring that the solution remained robust and suitable for continuous production.
The outcome shows that, when thermal control, cooling design, and structural considerations are properly aligned, stable and repeatable quality can be achieved in mass production, and also provides a practical reference for similar applications involving thick sections and localized hot spots.
8. Conclusion
For the M6 threaded boss shrinkage issue near the gate, Raidy Mold successfully:
- Identified the thermal root cause
- Re-engineered cooling and structure
- Eliminated critical porosity risks
- Enabled stable, high-quality production
Transforming a chronic defect into a controlled process parameter
If you are looking for a high-pressure die-casting mold manufacturer to cooperate with, please contact us to obtain design solutions and quotations.
