Reducing Shrinkage in Impeller Castings: Cutting Rejection Rate from 12% to 3%
Overview
A leading manufacturer of impellers faced significant challenges due to high rejection rates in casting, leading to increased costs and production delays. The primary defect observed was heavy shrinkage, impacting the integrity of the final product. This case study explores the engineering solutions implemented to reduce the rejection rate from 12% to 3%.
Background
The customer, engaged in a large-scale engineering project, approached Sevenloop with a critical issue regarding a 10.6 kg impeller casting. The casting failed to meet stringent requirements during final machining, necessitating an immediate resolution.
Challenges Identified
- Initial analysis of the rejected impeller casting revealed issues in casting methods and design.
- The shrinkage defects resulted in compromised product integrity.
- The existing casting orientation led to cross-feeding issues, contributing to shrinkage defects.
Solution Approach
To resolve the rejection issue, a structured three-step approach was undertaken:
1. Root Cause Analysis
- A detailed engineering review was conducted to identify defects in the casting process.
- The team examined potential improvements in design and process methodology.
2. Method Modification and Simulation
- The casting orientation was modified to prevent cross-feeding.
- The method was redesigned and validated using advanced casting simulation software.
- Shrinkage hotspots were analyzed, and process adjustments were implemented.
3. Production and Validation
- The modified casting method was implemented in production.
- The pouring process was optimized, ensuring uniform material flow.
- Quality inspections confirmed that all standards were met, eliminating previous defects.
Outcome
- Successful Casting: The modified casting method led to a significant reduction in shrinkage defects.
- Improved Quality: The rejection rate was reduced from 12% to just 3%.
- Customer Satisfaction: The project was completed successfully within the stipulated timeline, with no further rejections
Conclusion
- Method Optimization: This case study highlights the importance of method optimization and simulation in achieving defect-free castings within a short lead time.
- Advanced Engineering Techniques: Integrating modern engineering solutions minimized material wastage, enhanced quality, and ensured a first-time-right casting approach.
