Die casting is a cornerstone of high-volume metal manufacturing, especially for aluminum alloys, enabling the production of precise, complex parts used in automotive, electrónica, y ferretería. Yet many engineers and manufacturers still have questions: What’s the core mechanism behind die casting? How do key processes affect part quality? And what parameters need strict control? This article breaks down the fundamental principle, proceso paso a paso, optimización de parámetros, and quality control strategies of die casting—helping you master this efficient manufacturing technology.
1. Core Principle of Die Casting: How Does It Work?
En su corazón, die casting relies on high pressure and high speed to shape molten metal into precise parts. A continuación se muestra un Estructura de puntuación total explaining its key mechanisms, power sources, and critical conditions:
1.1 Fundamental Mechanism
Die casting’s core logic is “force-driven filling + pressure-assisted solidification”:
- High-Speed Injection: Metal fundido (P.EJ., aluminum alloy heated to 660~720°C) is injected into a precision metal mold cavity at speeds of 5~50 m/s. This ensures the metal flows quickly to fill even tiny mold details (P.EJ., 0.5mm-thin walls or embossed patterns) before solidifying.
- High-Pressure Holding: After the cavity is filled, the die-casting machine maintains a pressure of 20~150 MPa for 1~10 seconds. This compresses the molten metal, eliminates internal pores, and improves part density—critical for parts needing high strength (P.EJ., automotive engine brackets).
1.2 Power Source: The “Driving Force” of Die Casting
El hydraulic system of the die-casting machine is the key power provider:
- It drives the injection punch to push molten metal into the mold cavity (generating injection force).
- It controls mold clamping force (to keep the mold closed during high-pressure injection, preventing metal leakage).
- Para la producción a gran escala, modern machines use servo-hydraulic systems—reducing energy consumption by 30% compared to traditional hydraulic systems while ensuring stable pressure output.
1.3 Critical Conditions: Parameters That Determine Quality
Four core parameters must be strictly controlled to avoid defects like cold shuts (unfused metal seams) or shrinkage holes:
| Critical Parameter | Definición | Rango típico (Aleación de aluminio) | Impact on Quality |
| Temperatura del metal fundido | Temperature of the metal liquid before injection. | 660~720°C | Demasiado bajo: Poor fluidity → incomplete cavity filling. Demasiado alto: Grain coarsening → reduced part strength. |
| Temperatura del molde | Temperature of the metal mold before injection. | 180~ 250 ° C | Demasiado bajo: Metal solidifies too fast → cold shuts. Demasiado alto: Extended cooling time → low production efficiency. |
| Inyección | Pressure applied to push molten metal into the mold. | 20~ 150 MPa | Demasiado bajo: Internal pores → low part density. Demasiado alto: Mold damage or metal overflow → scrap parts. |
| Tiempo de llenado | Es hora de que el metal fundido llene toda la cavidad del molde.. | 0.01~0,1 segundos (piezas delgadas); 0.1~0.5 seconds (partes gruesas) | demasiado tiempo: Metal solidifies mid-flow → incomplete filling. Too short: Turbulence → air entrapment (porosidad). |
2. Step-by-Step Process of Die Casting: From Raw Material to Finished Part
The die casting process is a linear, sequential workflow—each step directly impacts the final part quality. A continuación se muestra un desglose del eje del tiempo del 6 pasos centrales, with key actions and quality checks:
2.1 Paso 1: Preparación de materia prima & Fusión
- Selección de material: Choose die-casting-specific alloys (P.EJ., aluminum alloy ADC12 for high fluidity, 6061 for high strength) that meet part performance needs.
- Fusión: Heat the alloy in a crucible furnace to 660~720°C. Use a temperature sensor to monitor in real time—avoid overheating.
- Desgásico & Refinación: Add scouring agents (P.EJ., hexacloroetano) to remove hydrogen (a major cause of porosity) e impurezas (P.EJ., slag). Para piezas de alta precisión, usar vacuum degassing—reducing hydrogen content by 80%.
Cheque de calidad: Use a metal sample analyzer to verify alloy composition (ensure no excess impurities like lead or cadmium).
2.2 Paso 2: Preparación de moho & Pretratamiento
- Instalación de moldes: Fix the pre-machined metal mold (made of H13 hot-work steel for wear resistance) to the die-casting machine’s fixed and moving platens. Align the mold carefully to avoid metal leakage.
- Mold Preheating: Heat the mold to 180~250°C using electric heaters or hot oil circulation. Use thermocouples to ensure uniform temperature (±10°C variation is acceptable).
- Release Agent Spraying: Spray a water-based or oil-based release agent on the mold cavity surface. Este: 1) Prevents metal from sticking to the mold; 2) Extends mold life (reduciendo el choque térmico); 3) Mejora el acabado superficial de la pieza..
Cheque de calidad: Inspeccione la cavidad del molde en busca de rayones o residuos; repare los rayones >0.1mm de profundidad para evitar defectos en la superficie de la pieza.
2.3 Paso 3: High-Pressure Injection
- Alimentación de metales: Vierta aleación de aluminio fundido en la cámara de presión de la máquina..
- Ejecución de inyección: El sistema hidráulico impulsa el punzón para empujar el metal dentro de la cavidad del molde a 5~50 m/s.. Para piezas complejas (P.EJ., gabinetes electrónicos), usar inyección de dos etapas: Baja velocidad (5~15m/s) para el llenado inicial (reduciendo la turbulencia) y alta velocidad (15~50m/s) para el relleno final (asegurando la replicación detallada).
Cheque de calidad: Monitor injection pressure in real time—abnormal spikes may indicate mold blockages (stop immediately to avoid machine damage).
2.4 Paso 4: Mantener la presión & Enfriamiento
- Mantener la presión: Maintain 20~150 MPa pressure for 1~10 seconds. This compresses the molten metal, eliminating shrinkage holes and improving density.
- Enfriamiento: Let the part solidify inside the mold. Cooling time depends on part thickness: 5~15 seconds for thin parts (P.EJ., 1mm-thick phone casings) and 15~60 seconds for thick parts (P.EJ., 10mm-thick automotive brackets).
Cheque de calidad: Use an infrared thermometer to confirm part temperature drops to 300~400°C (aleación de aluminio) before mold opening—too high a temperature causes part deformation.
2.5 Paso 5: Apertura del molde & Extracción de parte
- Apertura del molde: The die-casting machine’s hydraulic system pulls the moving platen back, opening the mold.
- Expulsión: An ejection mechanism (pins or plates) pushes the part out of the mold cavity. Para piezas frágiles (P.EJ., thin-walled electronics parts), usar multiple small ejection pins (instead of a single large pin) to avoid part cracking.
- Guarnición: Remove excess material (gate, riser, destello) using a trimming press or CNC router. Para piezas de alta precisión, use laser trimming—achieving a cutting accuracy of ±0.05mm.
Cheque de calidad: Inspect the part for surface defects (P.EJ., rebabas, arañazos)—burrs >0.03mm must be removed.
2.6 Paso 6: Post-tratamiento
Post-treatment enhances part performance and aesthetics. Choose processes based on part needs:
| Post-Treatment Type | Objetivo | Escenarios de aplicación |
| Tratamiento térmico | – Recocido: Eliminate internal stress (prevents part warping). – Envejecimiento: Improve strength (P.EJ., 6061 alloy strength increases by 40% after T6 aging). | Parts needing high strength (automotive drive shafts, componentes aeroespaciales). |
| Tratamiento superficial | – Ardor de arena: Create a matte finish (hides minor surface defects). – Pulido: Achieve a mirror finish (decorative parts like furniture hardware). – Anodizante: Form a protective alumina film (corrosion resistance for outdoor parts). – Electro Excripción: Add metal layers (chrome for wear resistance, nickel for decoration). | – Ardor de arena: Piezas industriales (alza de bombas). – Pulido: Piezas decorativas (manejos de grifo). – Anodizante: Accesorios al aire libre (street lamp brackets). – Electro Excripción: Adorno automotriz (manijas de las puertas). |
| Cheque de calidad: For anodized parts, test corrosion resistance via a salt spray test (must pass 48 hours without rust). |
3. Defectos comunes & Solución de problemas: How to Fix Issues
Even with strict process control, defects may occur. A continuación se muestra un ruptura de la cadena causal de 3 common defects and their solutions:
| Common Defect | Causa principal | Troubleshooting Solution |
| Cold Shuts (unfused metal seams on part surface) | 1. Molten metal temperature too low. 2. Mold temperature too low. 3. Filling time too long (metal solidifies mid-flow). | 1. Increase molten metal temperature by 10~20°C. 2. Raise mold temperature by 20~30°C. 3. Shorten filling time by 0.01~0.05 seconds (increase injection speed). |
| Porosidad (tiny holes inside the part) | 1. Desgasificación inadecuada (high hydrogen content). 2. Injection speed too fast (turbulence traps air). 3. Holding pressure too low (no pore compression). | 1. Extend degassing time by 2~5 minutes or use vacuum degassing. 2. Reduce injection speed by 5~10 m/s (use two-stage injection). 3. Increase holding pressure by 10~20 MPa. |
| Shrinkage Holes (large holes in thick part sections) | 1. Tiempo de espera demasiado corto (metal shrinks without pressure). 2. Cooling time too short (part not fully solidified). 3. Mold cavity design flawed (thick sections with no risers). | 1. Extend holding time by 1~3 seconds. 2. Increase cooling time by 5~10 seconds. 3. Modify mold design: Add risers (metal reservoirs) to thick sections. |
Yigu Technology’s Perspective on Die Casting Principle and Process
En la tecnología yigu, creemos “principle mastery + process refinement” is the key to stable die casting quality. Many clients struggle with recurring defects (P.EJ., porosidad) because they focus only on parameters, not the underlying principle (P.EJ., how hydrogen causes pores). We advocate a “3-layer approach”: 1) Train teams on die casting principles (P.EJ., pressure-assisted solidification) to help them understand por qué parameters matter; 2) Use intelligent monitoring systems to track real-time parameters (molten metal temperature, presión de inyección) and alert for deviations; 3) Para piezas personalizadas, optimize mold design (P.EJ., adding risers to thick sections) based on the filling principle—reducing defect rates by 40% de término medio. We also prioritize eco-friendly processes (P.EJ., servo-hydraulic machines, water-based release agents) to meet sustainability goals.
Preguntas frecuentes (Preguntas frecuentes)
- q: Why is mold preheating necessary? Can I skip it to save time?
A: No—mold preheating is critical. Cold molds cause molten metal to solidify too fast, leading to cold shuts (unfused seams) and poor part strength. Skipping preheating may seem to save 5~10 minutes per mold, but it increases scrap rates by 20~30%—costing more in the long run.
- q: Para fundición a presión de aleación de aluminio, what’s the difference between ADC12 and 6061 aleaciones? cual debo elegir?
A: ADC12 tiene alta fluidez (ideal para complejos, Piezas de paredes delgadas como cajas de componentes electrónicos.) pero menor fuerza. 6061 tiene mayor resistencia y resistencia a la corrosión (Adecuado para piezas que soportan carga, como soportes para automóviles.) pero menor fluidez. Elija ADC12 para formas complejas; elegir 6061 Para piezas que necesitan resistencia o uso en exteriores..
- q: Cómo confirmar si una pieza de fundición tiene porosidad interna? ¿Se puede arreglar después de la producción??
A: Usar inspección por rayos x (para piezas críticas como componentes aeroespaciales) o prueba hidrostática (for pressure-containing parts like pump housings) para detectar la porosidad interna. Small pores (≤0.1mm) can be fixed via impregnation (filling pores with resin or wax). Large pores (>0.1milímetros) usually require reworking or scrapping—better to prevent them by optimizing degassing and holding pressure during production.