During the mass production phase of the engine cylinder head cover die-casting mold project, the client’s original mold was developed and manufactured by another supplier. However, during the actual die-casting and subsequent machining processes, severe porosity defects frequently appeared in the threaded hole area of critical cylinder positions, resulting in a product defect rate as high as 39.6%.
Because the problem occurred during the mass production stage, a large number of castings were scrapped after machining, and the quality loss rapidly increased. The client not only faced continuously rising scrap costs but also had to repeatedly communicate with the original supplier regarding the division of responsibility and compensation plans, leading to a stalemate in the project and significantly impacting delivery and production schedules.
With the increasing pressure of quality risks and costs, the client decided to conduct a comprehensive technical review of the mold structure and filling system and introduced a professional team with high-pressure die-casting mold flow analysis and structural optimization capabilities for system improvement. We thus officially participated in the project.
Background of the Engine Cylinder Head Cover Die-casting Mold Project:
Severe Porosity in Threaded Holes After Machining, Defect Rate as High as 39.6%
In a high-pressure die-casting mold project for an automotive engine aluminum alloy cylinder head cover, the product’s appearance was basically normal during the die-casting stage, but serious quality problems were exposed during subsequent machining. In the two critical column areas, significant porosity defects were found inside the threaded holes after machining, failing to meet strength and sealing requirements, resulting in batch defects.
Statistical data from the project’s trial production phase showed:
- Porosity concentration in threaded hole locations
- Defect rate as high as 39.6%
- Monthly supply of approximately 16,000 units
- Severe scrap losses directly impacted delivery and cost control
- The problem has escalated from localized porosity defects to a cost and quality risk for the entire production line.
Root Cause Analysis:
Localized air entrapment leading to concentrated porosity
- We conducted a systematic analysis of the die-casting mold problem, including:
- Mold flow filling path analysis
- Air entrapment distribution tracking
- Sprue cross-sectional area calculation
- Local flow velocity variation assessment
Through MAGMA simulation, we found:
- The original sprue width was too narrow, and the filling speed was too high
- Secondary backflow of molten metal occurred in the column area
- Poor venting in localized areas
- Severe air entrapment and porosity accumulation
- Especially at the roots of the two columns, the high-speed impact of molten metal created a turbulent zone, causing air to be trapped within the threaded hole forming area.
This problem is a typical example of a high-pressure die-casting defect model characterized by: “complex local structure + unreasonable gating design + concentrated air entrapment.”
Die-casting Mold Solution
Adding bridging structures + widening the gating structure for optimization. Addressing the root cause, we propose a structural optimization solution, rather than simply adjusting process parameters.
Optimization measures include:
- Adding bridging structures in key areas of the cylinder head cover.
Optimizing the direction of molten metal flow.
Balancing filling pressure.
Reducing turbulence formation. - Widening the gating cross-sectional area.
Reducing local flow velocity.
Reducing molten metal impact.
Improving filling stability. - Re-optimizing the overflow and venting layout.
MAGMA Simulation Verification:
Significantly Improved Air Enrapment in High-Pressure Die-casting Molds.
After structural adjustments, we conducted comparative simulation analysis using MAGMA.
Simulation results show:
The integral number of enrapped gas at the defect location is significantly reduced.
Filling in the threaded hole area is more stable.
Local turbulence intensity decreases.
Simulation results are highly consistent with actual trial production data.
Improvement Results:
The defect rate for the automotive cylinder head cover die-casting mold project decreased from 39.6% to 3.2%, resulting in annual cost savings of $1,210,000.
After implementing the optimization plan, the project achieved significant results:
Defect rate decreased from 39.6% to 3.2%
Monthly supply of 16,000 units was delivered stably
Annual cost savings of approximately $8.38 million.
This improvement not only reduced direct scrap losses but also brought systemic benefits.
Quality and Efficiency Improvement:
Significantly Improved OEE
After the substantial reduction in the defect rate:
Rework rate decreased significantly
Production cycle became more stable
Equipment downtime decreased
Overall equipment efficiency (OEE) was significantly improved, and production line stability was significantly enhanced.
Development Cycle Shortened by 36 Days:
The Efficiency Value of Pre-Mold Simulation
During the improvement process, this project achieved the following through:
Early-stage DFM assessment
Mold flow simulation verification
Rapid structural iteration
Compared to the traditional “trial molding—modification—re-trial molding” approach, the overall development cycle was shortened by 36 days.
This illustrates that scientific verification during the high-pressure die-casting mold design phase is crucial for controlling quality and cost. Raidy Molds is committed to manufacturing high-quality, high-yield die-casting molds.
Cylinder Head Cover Mold: Before & After
| Project Metrics | Before Optimization | After Optimization | Improvement |
|---|---|---|---|
| Thread Hole Defect Rate | 39.6% | 3.2% | Reduced by 36.4% |
| Monthly Production | 16,000 units | 16,000 units | Stable supply |
| Annual Cost Loss | High | Saved approx. $1,210,000 | Significant savings |
| Production Line Stability | Unstable, frequent rework | Stable, rework greatly reduced | Significant improvement |
| OEE (Overall Equipment Efficiency) | Low | Significantly improved | Higher production efficiency |
| Development Cycle | Traditional trial mold → modification → re-trial | Structural optimization + mold flow verification | Shortened by 36 days |
From Localized Porosity to Systematic Mold Design Capabilities – Quality Assurance for the Automotive Industry
This project addresses more than just the localized porosity issue in a threaded hole; it validates the systemic design capabilities for automotive aluminum alloy structural components.
In the automotive industry, especially in engine systems, new energy structural components, and lightweight parts, high-pressure die-cast aluminum parts are no longer merely aesthetic components; they are critical functional components responsible for structural strength, sealing performance, and long-term reliability.
The impact of porosity extends far beyond surface defects:
It weakens local structural strength, affecting thread fastening reliability.
It can lead to seal failure, causing leakage risks.
Under high-temperature and high-vibration conditions, micro-porosity can evolve into fatigue crack initiation points.
Long-term operation may even affect the stability of the entire system.
Therefore, true quality control in automotive die casting should not stop at “defect repair,” but should be built upon systematic mold design capabilities.
Raidy Mold, a manufacturer specializing in automotive aluminum high-pressure die-casting molds, consistently adheres to the following principles: Early-stage DFM structural assessment; MAGMA mold flow simulation verification; Co-optimization of gating and venting systems; Cooling and thermal balance control design; Building a complete high-pressure die-casting mold system design framework.
Through bridging optimization, gating structure upgrades, and simulation-driven design decisions, this case study achieved a shift from “defect response” to “source prevention.” This systematic approach not only solves single-project problems but also provides automotive customers with replicable, verifiable, and sustainable quality assurance capabilities.
In the context of increasingly fierce competition and ever-rising quality standards in the automotive industry, mold manufacturers have evolved from simple processing suppliers to key players in product reliability.
This is precisely the core value of Raidy Mold’s continuous deep cultivation in the field of automotive high-pressure die-casting molds.
FAQ
Q1: Why did the original die-casting mold produce threaded holes and porosity?
A1: The original mold’s gating and venting design was flawed. Localized turbulence caused air trapping, resulting in severe porosity after machining.
Q2: Can adjusting the process solve the problem?
A2: Process adjustments alone cannot fundamentally solve the problem. Structural optimization is needed to improve filling stability and venting effectiveness.
Q3: What are the optimization solutions for Raidy Mold?
A3: Adding bridging structures, optimizing the gating direction, widening the gate, and improving overflow and venting design to reduce localized turbulence and air trapping.
Q4: What are the optimization effects of this high-pressure die-casting mold?
A4: The defect rate decreased from 39.6% to 3.2%, annual cost savings were approximately $1.21 million, production became more stable, OEE improved, and the development cycle was shortened by 36 days.
Q5: What is the long-term value for customers? A5: Improve the strength and sealing reliability of threaded holes, reduce long-term fatigue risks, and establish a replicable, systematic high-pressure casting mold design capability.
Conclusion
By adding a bridging structure and optimizing the gating design, combined with MAGMA mold flow simulation verification, this project successfully solved the porosity problem of the cylinder head cover’s stud threaded holes.
Project Outcomes: Defect rate reduced by over 36%; Annual cost savings of $1,210,000; Significantly improved OEE; Development cycle shortened by 36 days. This fully demonstrates the core value of scientific high-pressure die-casting mold design and simulation analysis in the automotive aluminum die-casting field.
Making mold design the starting point for quality assurance, not a source of risk. Raidy Mold focuses on optimizing automotive aluminum high-pressure die-casting mold systems, helping customers reduce defect rates, improve OEE, and shorten development cycles. Contact us to unlock a more stable and efficient mass production solution.
