The market demand and mold technology bottlenecks of V10 engines

The global marine V10 engine market has been expanding at an average annual growth rate of 4.2%, with production exceeding 12,000 units in 2023. Each engine cylinder block requires 3 sets of die-casting molds (body mold, crankshaft chamber mold, and cooling water channel mold). Considering the mold life cycle and the demand for parallel production of multiple models, the annual new demand for mold frames reaches 800-1,200 sets.

The complexity of mold structures is reflected in:

A 120° V-angle area that needs to integrate 16 groups of hydraulic core-pulling mechanisms.

The cavity tolerance requirement is ≤0.05mm.

The matching accuracy of multi-directional parting surfaces needs to be controlled within 0.1mm/m.

Process Limitations of Traditional Cast Steel Mold Bases

Japanese manufacturers have long employed SCMN-2A cast mold bases (C: 0.25-0.35%, Cr: 1.8-2.2%, Mo: 0.9-1.2%), which are produced via sand casting to obtain near-net-shape blanks, followed by 180 hours of precision machining to achieve the final form. Although this process reduces initial machining costs, the material inherently contains 2-3% shrinkage porosity, leading to the following issues:

Uncontrollable Deformation in High-Pressure Casting: Under an injection pressure of 70 MPa, the guide rail areas of the mold base exhibit elastic deformation of 0.3-0.5 mm, resulting in casting wall thickness deviations of up to ±0.25 mm.

Thermal Fatigue Life Degradation: During continuous die-casting, the surface temperature of the mold base fluctuates between 280–420°C. After 30,000 cycles, SCMN-2A develops a cumulative thermal expansion error of 0.15 mm.

Manufacturing Challenges of P20 Mold Bases

Despite their significant performance advantages, P20 mold base manufacturing faces three major technical barriers:

Long Machining Time and High Precision Requirements for Machine Tools:

P20 forged steel has high hardness (HRC 28-35), making it difficult to machine. A single mold base can take over 450 hours to process—1.5 times longer than traditional cast steel mold bases.

High-precision machine tools (positioning accuracy ≤ 0.005 mm) and a temperature-controlled workshop (fluctuations within ±1°C) are required to ensure machining precision.

The complex structure of P20 mold bases places extremely high demands on the dynamic response and stability of machine tools, particularly during angled core-pulling and deep-hole machining. Rigidity, vibration suppression, and thermal stability directly affect machining quality.

High Tooling Requirements:

The high hardness and wear resistance of P20 forged steel impose stricter demands on cutting tools. High-performance carbide tools (e.g., TiAlN-coated tools) or CBN tools must be used, increasing tool costs by 40–60% compared to standard tools.

Due to P20’s pronounced work-hardening tendency, tool wear accelerates, requiring frequent replacements and further raising machining costs and time.

Lightweight Design Paradox:

A 15–20% weight reduction must be achieved while maintaining stiffness.

Topology optimization can be employed to reinforce high-stress areas with ribs and use honeycomb hollowing in non-load-bearing zones.

Precision Control in Angled Core-Pulling:

The 120° V-shaped core-pulling guide rails must maintain a straightness of 0.008 mm.

Real-time compensation for tool wear-induced trajectory deviations is necessary during machining.

Surface Strengthening Treatment:

Low-temperature ion sulfurization (250°C × 6h) can be applied to working surfaces, forming a 5–8 μm FeS layer that reduces the friction coefficient from 0.18 to 0.09.

This treatment decreases wear on core-pulling mechanisms by 72%.

Improvements Needed by Mold Base Manufacturers

To address the challenges of P20 mold base manufacturing, mold base factories must make comprehensive upgrades in the following areas:

Enhance Pre-Machining Process Analysis:

Conduct thorough process analysis before machining, including stress distribution, thermal deformation prediction, and machining path optimization, to ensure feasibility and cost-effectiveness.

Develop detailed machining process cards specifying parameters, tool selection, and inspection requirements for each step to ensure process control.

Adopt Advanced Machining Equipment and Process Software:

Introduce high-precision machining centers to achieve machining accuracy within 0.005 mm.

Utilize advanced CAM systems to optimize toolpaths, reduce idle time, and improve efficiency.

Implement adaptive machining systems to dynamically adjust parameters and compensate for tool wear and material deformation.

Strengthen Environmental and Temperature Control:

Establish temperature-controlled workshops (±1°C) to minimize thermal deformation effects on precision.

Install air purification systems to regulate dust and humidity, ensuring a stable machining environment.

Enhance In-Process Inspection and Quality Control:

Introduce real-time measurement systems to monitor machining dimensions, ensuring critical tolerances stay within ±0.01 mm.

Use laser scanners for full-dimensional inspection of complex surfaces, ensuring cavity accuracy meets design specifications.

Improve Employee Training and Skill Development:

Conduct regular training sessions on P20 material machining to enhance operators' understanding and skills.

Implement digital training platforms with virtual simulations to familiarize workers with complex machining processes and machine operations.

Establish a skill certification system to ensure key personnel possess the necessary technical qualifications.

Conclusion

With the trend toward larger and lighter automotive engines, the demand for high-reliability die-casting molds is increasing. P20 forged steel mold bases offer significant potential but also present considerable challenges. Mold base manufacturers must understand market demands and enhance their capabilities to achieve sustainable and high-quality development.