In die casting production—whether for new energy vehicle motor housings or 5G base station cooling modules—post-processing of die casting is the final step that turns raw castings into high-performance, market-ready parts. It fixes casting defects, optimizes surface quality, and ensures parts meet design standards. This article breaks down its core goals, procesos clave, quality control methods, defect solutions, and cost-saving tips, helping you build a efficient post-processing workflow.
1. What Are the Core Goals and Principles of Die Casting Post-Processing?
Post-processing isn’t random—it follows clear goals and principles to avoid rework and ensure consistency.
1.1 Core Goals
The work focuses on four key objectives, tailored to part functions:
- Eliminate Casting Defects: Fix issues like shrinkage, pores, and flash left from casting.
- Optimize Surface Quality: Achieve smooth finishes or protective coatings for appearance and durability.
- Adjust Mechanical Properties: Boost strength, dureza, or creep resistance through heat treatment.
- Meet Design Accuracy: Ensure dimensions, llanura, and other specs match engineering requirements.
1.2 Guiding Principles
To prevent secondary damage and save time, two rules are non-negotiable:
- “Rough First, Then Fine”: Do heavy-duty work (like cutting sprues) primero, then precision tasks (como moler). This avoids scratching finished surfaces.
- “Inside First, Then Outside”: Machine internal features (like holes) before external ones. Internal machining is more likely to cause minor deformation, which can be corrected when finishing the exterior.
2. What Are the Key Processes in Die Casting Post-Processing?
Post-processing has five core steps, each with specific techniques and parameters. Below is a detailed breakdown for industrial use:
2.1 Sprue, Riser, and Flash Removal
This step cleans up excess material from casting. The method depends on production volume and precision needs:
Lote de producción | Recommended Method | Ventajas clave | Parámetros críticos |
Producción en masa | Automatic Stamping & Cizallamiento | Alta eficiencia (1000+ piezas/hora); Flat cross-sections | Retain 1-2mm margin to protect the part body; Cut angle <5° |
Small-Medium Batches | Grinding Wheel/Diamond Saw Cutting | Flexible (works for odd-shaped parts); Low equipment cost | Use diamond blades for aluminum alloys to reduce burrs |
High-Precision Parts | Five-Axis Laser Cutting | No deformation risk; Corta formas complejas | Laser power: 500-1000W.; Velocidad de corte: 100-300mm/min |
Nota: Usar corte frío for aluminum-magnesium alloys to avoid heat-affected zones that weaken the part.
2.2 Surface Treatment Combinations
Surface treatment improves appearance, resistencia a la corrosión, y funcionalidad. Choose based on material and part use:
Treatment Level | Técnicas | Especificaciones clave | Materiales adecuados | Beneficios |
Basic Treatment | – Vibration Grinding (ceramic medium + alkaline solution)- Ardor de arena (ASTM B243 ALMEN standard)- Chemical Degreasing (ultrasound-assisted) | – Deburrs edges- Ra=3.2-6.3μm (ardor de arena)- Contact angle <5° (desengrasante) | All die casting metals | Prepares surfaces for advanced treatments; Removes oil/dirt |
Advanced Treatment | – Anodizante- Micro-Arc Oxidation- Revestimiento de polvo- Electro Excripción | – Corrosion resistance ×3 (Anodizante)- Hardness HV≥800 (oxidación por microarco)- Prueba de spray de sal >1000h (revestimiento de polvo)- Gloss 90GU (electro Excripción) | – Anodizante: Aleaciones de aluminio- Micro-arc oxidation: Al/Mg/Ti alloys- Revestimiento de polvo: Todos los metales- Electro Excripción: Copper/zinc alloys | Tailored to needs—e.g., anodizing for automotive parts; electroplating for decorative components |
2.3 Mecanizado de precisión
This step refines dimensions and shapes. Success depends on clamping strategies and parameter optimization:
2.3.1 Clamping Strategies for Different Part Types
Tipo de parte | Método de sujeción | Exactitud | Caso de uso |
Thin-Walled Parts (<3milímetros) | Vacuum Suction Cup + Honeycomb Support Pad | Prevents deformation | Aluminum alloy laptop casings |
Irregular-Shaped Parts | 3D-Printed Custom Fixtures | Error <0.02milímetros | 5G base station cooling modules |
Multi-Process Parts | Zero-Point Positioning System | Repeat positioning <0.01milímetros | New energy vehicle motor housings |
2.3.2 Optimized Machining Parameters
Material | Process Type | Feed per Tooth (milímetros) | Profundidad de corte (milímetros) | Velocidad de corte (m/mi) | Método de enfriamiento |
Aleación de aluminio | Toscante | 0.15-0.25 | 0.8-1.2 | N / A | Low-temperature compressed air + micro-lubrication |
Acero inoxidable | Refinamiento | N / A | Radial <0.5 | 80-120 | Same as above |
2.4 Heat Treatment Strengthening
Heat treatment boosts mechanical properties. Utilice esquemas específicos de materiales.:
Material | Esquema de tratamiento térmico | Parámetros clave | Resultados |
Aleación de aluminio A380 | Envejecimiento de la solución T6 | 535±5°C durante 8-12h; Transferencia de enfriamiento <30s | Resistencia a la tracción σb=320MPa; Alargamiento δ=8% |
Aleación de magnesio ZAM4-1 | Envejecimiento artificial T6 | 415±5°C durante 24h; Protección con gas inerte | Dureza Brinell HB=90; Resistencia a la fluencia ↓40% |
Aleación de zinc ZA27 | Endurecimiento por edad | 90-120°C durante 4-8 h; Temperatura < punto eutéctico | Dureza Rockwell HRB=95; Estabilidad dimensional |
Notas críticas: Las aleaciones de magnesio necesitan gas inerte para evitar la oxidación; Las aleaciones de zinc no deben exceder la temperatura eutéctica. (causa derretimiento).
2.5 Special Processing
Para alivio de tensiones residuales y protección de sellado.:
Objetivo | Técnicas | Parámetros | Beneficios |
Alivio del estrés residual | – Vibration Aging- Tratamiento criogénico | – Frequency 2-50kHz; Amplitude 15-50μm- -196°C liquid nitrogen for 48h | Fatigue life ×2-3 (aleaciones de aluminio); Prevents long-term deformation |
Sealing Protection | – Silicone Rubber Impregnation (VIPI)- PARYLENE Vapor Deposition | – Pressure resistance IP68- Film thickness 5-25μm | Waterproof/dustproof; Protects electronics (P.EJ., carcasa del sensor) |
3. How to Control Quality in Die Casting Post-Processing?
Quality control ensures parts meet standards. Use the right tools and tests:
Quality Aspect | Método de prueba | Standards/Requirements |
Precisión dimensional | Coordinar la máquina de medir (Cmm) | GB/T 6414 CT7 |
Air Tightness | HE High-Pressure Leak Detection | Leakage rate <1cm³/[email protected] |
Aspereza de la superficie | White Light Interferometer | Decorative surfaces: Ra≤0.8μm |
Adhesión de recubrimiento | Grid Test + Tape Peeling | ASTM D3359 Method B |
Defectos internos | X-Ray Fluorescence + CT Scanning | ISO 17636-1 Level B |
4. How to Fix Common Post-Processing Defects?
Defects like shrinkage or pores can be resolved with targeted solutions:
Defecto | Causa | Solución |
Contracción (X-ray cloud-like shadows) | Insufficient cooling during casting | Add cooling inserts; Extend holding time to 8-12s |
Peeling (separación de capas) | Large mold temperature gradient | Use mold temperature controller to keep inlet/outlet temp difference <5° C |
Pores (tiny air bubbles) | Trapped air during casting | Add more exhaust grooves; Adjust backpressure valve |
Deformación | Residual stress release | Manual aging treatment; Use calibration fixtures |
Baja dureza (CDH<48) | Inadequate heat treatment | Laser cladding with TSN coating (hardness HRC62) |
5. How to Control Costs and Cycles in Post-Processing?
Post-processing accounts for a large portion of total costs—optimize to save money and time:
Paso postprocesado | Cost Share | Cycle Share | Consejos de optimización | Resultados |
Basic Treatment | 15-25% | 20-30% | Use automatic rolling grinding lines | Manpower saved by 70% |
Tratamiento superficial | 20-35% | 15-25% | Build coating recycling systems | Consumables reduced by 40% |
Mecanizado de precisión | 30-40% | 30-40% | Adopt turn-mill composite machining centers | Cycle time shortened by 50% |
Inspección de calidad | 5-10% | 5-10% | Replace manual checks with AI visual inspection | Missed detection rate <0.1% |
6. Yigu Technology’s Perspective on Post-Processing of Die Casting
En la tecnología yigu, vemos post-processing of die casting as the “value-adding bridge” between raw castings and high-quality parts. Nuestros datos muestran 70% of part failures stem from rushed or mismatched post-processing—e.g., using heat treatment on porous aluminum parts causes cracking.
We recommend a “process-material matching” approach: For ADC12 aluminum alloy motor housings, we pair T6 heat treatment with precision boring to hit flatness <0.05mm/100mm; For Zamak5 zinc alloy medical handles, we use nano-chrome plating + laser engraving to meet ISO 10993 Normas de biocompatibilidad. By integrating automation (like AI inspection) and material-specific schemes, we help clients cut costs by 25% while improving part reliability.
7. Preguntas frecuentes: Common Questions About Post-Processing of Die Casting
Q1: Can all die casting materials use the same surface treatment?
No. Por ejemplo, anodizing only works on aluminum alloys (it forms an oxide layer), while micro-arc oxidation is better for Al/Mg/Ti alloys. Zinc alloys are often electroplated for decoration, but powder coating works for most metals—always match the treatment to the material and part function.
Q2: Why is quench transfer time critical for aluminum alloy heat treatment?
Aleaciones de aluminio (like A380) need fast quenching after solution treatment to trap strengthening elements. If transfer time exceeds 30 artículos de segunda clase, elements precipitate early, reducing tensile strength by up to 20%. We use automated quenching systems to keep transfer time <25 artículos de segunda clase.
Q3: How to reduce deformation in thin-walled die casting post-processing?
Use three methods: 1) Clamp with vacuum suction cups + honeycomb pads to spread pressure; 2) Use low cutting speeds (50-80m/min para aluminio) to minimize force; 3) Add a cryogenic treatment step (-196°C for 24h) to release residual stress before precision machining. These cut deformation by 60%.