Le moulage sous pression semi-solide et le moulage sous pression ordinaire sont deux technologies de base dans le formage des métaux., chacun optimisé pour différents besoins de production. Tandis que tous deux injectent du métal dans des moules pour créer des pièces, leurs différences fondamentales dans l'état du métal, contrôle de processus, et leurs performances les rendent adaptés à des applications distinctes, des composants automobiles à haute résistance aux biens de consommation à faible coût.. Mais qu'est-ce qui les distingue exactement? How do these differences impact cost, efficacité, et qualité des pièces? And how do you choose the right technology for your project? This article answers these questions with detailed comparisons and actionable insights.
1. Core Definitions & Principes: The Fundamental Gap
The biggest difference between the two technologies lies in the state of the metal during processing, which shapes their entire working mechanisms.
UN. Ordinary Die Casting
- Metal State: Utilisations fully molten liquid metal (par ex., aluminum alloy heated to ≥650°C). The metal flows like water, with low viscosity and Newtonian fluid characteristics.
- Core Mechanism: Relies on high speed and high pressure (typical pressure: 100–150MPa) to force liquid metal to fill complex mold cavities quickly (often in <0.1 secondes). Rapid cooling in the mold then solidifies the metal into the desired shape.
- Microstructure Result: Due to fast cooling, the final part has fine but unevenly distributed grains, plus a large number of eutectic structures. This often leads to defects like shrinkage holes et stomata (porosité), especially in thick-walled areas.
B. Semi-Solid Die Casting
- Metal State: Utilisations semi-solid slurry or billets—a solid-liquid coexistence state (solid fraction: 50–90%). The metal behaves like “toothpaste”: épais, viscous, and non-Newtonian (its flowability improves with shear force).
- Core Mechanism: Leverages the high viscosity and non-dendritic microstructure of semi-solid metal. It fills the mold at a slower, more controlled speed (no turbulent splashing), reducing gas entrainment and defect risks.
- Microstructure Result: Spherical primary solid phase particles are evenly distributed in the liquid phase. After solidification, the part has fine spherical grains and a fibrous matrix, leading to better mechanical property uniformity (isotropy) and fewer defects.
2. Side-by-Side Process Comparison: Key Operational Differences
To understand how these technologies perform in practice, let’s compare their process steps, paramètres, and constraints in a clear table:
| Process Aspect | Ordinary Die Casting | Semi-Solid Die Casting |
| Metal Pretreatment | Simple: Melt metal directly to a liquid state; no special preparation. | Complexe: Requires semi-solid slurry/billet production (via mechanical mixing, electromagnetic stirring, or low-temperature deposition). |
| Filling Characteristics | High-speed jetting (souvent >5MS); prone to eddy currents and metal splashing. | Lent, smooth filling (typiquement <2MS); high viscosity prevents turbulence. |
| Typical Operating Pressure | 100–150MPa (needs high pressure to overcome liquid metal inertia). | 60–100MPa (lower pressure due to reduced flow resistance of semi-solid metal). |
| Mold Heat Load | Extremely high (liquid metal releases large latent heat); requires a powerful cooling system (par ex., water channels every 20mm). | Faible (semi-solid metal has less latent heat to release); cooling system can be simpler. |
| Solidification Shrinkage | Grand (liquid metal contracts significantly during cooling); easy to form shrinkage defects. | Smaller (solid phase already dominates the metal, reducing total contraction). |
| Minimum Wall Thickness | Capable of ultra-thin walls (jusqu'à 0,5 mm); ideal for lightweight parts. | Limité (typical minimum: ≥1mm); semi-solid metal’s viscosity struggles to fill tiny gaps. |
| Temps de cycle | Extremely fast (<30 secondes par partie); no extra steps for slurry preparation. | Plus long (45–90 seconds per part); includes time for slurry production or billet reheating. |
3. Performance & Application: Which Shines Where?
The process differences directly translate to distinct performance advantages—making each technology better suited for specific part types.
UN. Performance Comparison
| Performance Metric | Ordinary Die Casting | Semi-Solid Die Casting |
| Résistance à la traction | Inférieur (par ex., 200–250MPa for aluminum alloys). | Plus haut (15–30% increase; par ex., 230–325MPa for aluminum alloys). |
| Élongation | Faible (typically 2–5% for aluminum parts). | Doubled (4–10% for aluminum parts); spherical grains hinder crack propagation. |
| Taux de défauts | Haut (porosity and shrinkage are common; taux de rebut: 5–12%). | Faible (greatly reduces stomata and shrinkage; taux de rebut: 1–3%). |
| Heat Treatment Stability | Pauvre (heat treatment often expands existing pores, causing deformation). | Excellent (uniform microstructure resists deformation; suitable for T6 heat treatment). |
| Coût par pièce | Faible (\(0.3–)1 per kg for aluminum parts); mature equipment and simple process. | Haut (\(0.8–)2 per kg for aluminum parts); needs special slurry equipment. |
B. Application Scenarios: Choosing the Right Fit
The table below maps each technology to its ideal use cases, based on performance and cost needs:
| Part Requirement | Prefer Semi-Solid Die Casting | Prefer Ordinary Die Casting |
| Safety-Critical Parts | Automotive steering knuckles, étriers de frein (need high strength and low defects). | None—safety parts require reliability beyond ordinary die casting’s capabilities. |
| Pressure-Resistant Components | Hydraulic valve bodies, air compressor cylinders (no pores to leak under pressure). | Small electrical enclosures (no pressure load; cost is key). |
| High-Toughness Needs | Motorcycle hubs, golf heads (must withstand impact without cracking). | Toy models, simple brackets (low impact risk). |
| High-Temperature Service | Engine head brackets (stable microstructure resists heat deformation). | Poignées d'ustensiles de cuisine (low heat exposure; cost matters more). |
| Ultra-Thin or High-Volume Parts | None—struggles with thin walls and slow cycle times. | Home appliance shells, lamp frames, boîtiers pour appareils électroniques grand public (volume élevé, faible coût). |
4. Équipement & Coût: The Investment Tradeoff
Choosing between the two technologies also means evaluating upfront and long-term costs, driven by equipment differences.
UN. Equipment Requirements
| Equipment Type | Ordinary Die Casting | Semi-Solid Die Casting |
| Core Machine | Standard die casting machine (par ex., 200–300-ton models); widely available. | Specialized machine with slurry feeding systems; often custom-built. |
| Pretreatment Gear | Basic melting furnace (no extra tools needed). | Slurry preparation equipment (par ex., electromagnetic stirrers, low-temperature deposition units). |
| Conception de moules | Simple molds (focus on fast cooling; no special flow controls). | Molds with optimized gating (to handle viscous semi-solid metal; may need larger runners). |
B. Cost Breakdown (Aluminum Alloy Parts, 10,000-Part Batch)
| Cost Category | Ordinary Die Casting | Semi-Solid Die Casting |
| Equipment Investment | \(50,000–)100,000 (standard machine + furnace). | \(150,000–)300,000 (specialized machine + slurry gear). |
| Mold Cost | \(5,000–)15,000 (simple design, no complex features). | \(10,000–)25,000 (optimized for semi-solid flow). |
| Per-Part Material Cost | \(0.3–)0.5 (higher waste rate: 10–15% due to defects). | \(0.4–)0.6 (lower waste rate: 3–5% fewer defects). |
| Total Batch Cost | ~\(8,000–)17,500 | ~\(25,000–)51,000 |
5. Technological Evolution: Future Trends
Both technologies are evolving to address their limitations—with semi-solid casting leading in innovation for high-performance needs.
UN. Semi-Solid Die Casting Innovations
- Intelligent Slurry Control: Real-time electromagnetic stirring devices now monitor and adjust the solid fraction (to ±2%) during slurry production, ensuring consistent metal quality.
- Composite Molding: Combining semi-solid casting with squeeze casting further increases part density (reducing remaining porosity to <0.5%).
- New Material Adaptation: Expanding to magnesium alloys (plus léger que l'aluminium) and high-entropy alloys (superior heat resistance), opening doors for aerospace applications.
- Green Manufacturing: Uses ~20% less energy than ordinary die casting (no need to fully melt metal), s'aligner sur les objectifs de développement durable.
B. Ordinary Die Casting Improvements
- Defect Reduction: Adding vacuum systems to remove gas during filling reduces porosity by 30–40%.
- Automation: Fully automated lines (with robotic part removal) cut labor costs by 50% and boost cycle time consistency.
6. Yigu Technology’s Perspective on the Two Technologies
Chez Yigu Technologie, we see semi-solid and ordinary die casting as complementary tools—not competitors. For automotive clients needing safety parts (par ex., étriers de frein), our semi-solid die casting solutions (equipped with real-time slurry monitoring) deliver tensile strength gains of 25% and scrap rates below 2%, meeting IATF 16949 normes. For consumer electronics clients, our optimized ordinary die casting lines (with vacuum degassing) reduce costs by 30% while keeping defects low enough for non-load parts.
We’re investing in “hybrid manufacturing” models: using semi-solid casting for high-strength main structures and ordinary casting for secondary features (par ex., integrated die-cast automotive bodies). This balances performance and cost, helping clients avoid overpaying for technology they don’t need. Our goal is to tailor each solution to the part’s actual requirements—no one-size-fits-all.
FAQ
- Can semi-solid die casting be used for ultra-thin parts (par ex., 0.5murs mm)?
No—semi-solid metal’s high viscosity makes it hard to fill tiny gaps. Ultra-thin parts (≤0.8mm) are better suited for ordinary die casting, which uses low-viscosity liquid metal to reach narrow cavities. For parts with mixed thicknesses (par ex., a 1mm main body + 0.6mm ribs), consider hybrid designs: use semi-solid casting for the main body and post-machine the thin ribs.
- Is semi-solid die casting worth the higher cost for non-safety parts?
It depends on the part’s function. If the part needs to withstand impact, pression, or heat (par ex., raccords hydrauliques), yes—semi-solid casting’s durability reduces long-term maintenance costs. If it’s a non-load decorative part (par ex., abat-jour), ordinary die casting is more cost-effective. We recommend calculating the “total cost of ownership” (not just per-part cost) to decide.
- Can ordinary die casting parts be heat-treated to match semi-solid casting performance?
Rarely—ordinary die casting parts have hidden pores and uneven microstructures. Traitement thermique (par ex., T6) often expands these pores, causing deformation or even cracking. Semi-solid casting parts, with their uniform spherical grains, can handle heat treatment without issues, but ordinary parts typically cannot achieve the same strength gains. For heat-treated parts, semi-solid casting is the more reliable choice.