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, key processes, 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, поры, and flash left from casting.
- Optimize Surface Quality: Achieve smooth finishes or protective coatings for appearance and durability.
- Adjust Mechanical Properties: Boost strength, твердость, or creep resistance through heat treatment.
- Meet Design Accuracy: Ensure dimensions, плоскостность, 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) первый, then precision tasks (как шлифование). 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:
Производственная партия | Рекомендуемый метод | Ключевые преимущества | Critical Parameters |
Массовое производство | Automatic Stamping & Сдвиг | Высокая эффективность (1000+ части/час); Flat cross-sections | Retain 1-2mm margin to protect the part body; Cut angle <5° |
Small-Medium Batches | Grinding Wheel/Diamond Saw Cutting | Гибкий (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; Резает сложные формы | Laser power: 500-1000W.; Скорость резки: 100-300мм/мин |
Примечание: Использовать холодная резка for aluminum-magnesium alloys to avoid heat-affected zones that weaken the part.
2.2 Surface Treatment Combinations
Surface treatment improves appearance, коррозионная стойкость, и функциональность. Choose based on material and part use:
Treatment Level | Методы | Ключевые спецификации | Подходящие материалы | Преимущества |
Basic Treatment | – Vibration Grinding (ceramic medium + alkaline solution)- Песчаная обработка (Общий стандарт ASTM B243)- Химическое обезжиривание (с помощью ультразвука) | – Удаление заусенцев с кромок- Ra=3,2-6,3 мкм (песчаная обработка)- Угол контакта <5° (обезжиривание) | Все металлы для литья под давлением | Подготавливает поверхности для сложных процедур.; Удаляет масло/грязь |
Расширенное лечение | – Анодирование- Микродуговое оксидирование- Порошковое покрытие- Гальванизация | – Коррозионная стойкость ×3 (Анодирование)- Твердость HV≥800 (микродуговое оксидирование)- Тест на соленый спрей >1000час (Порошковое покрытие)- Глянец 90ГУ (гальванизация) | – Анодирование: Алюминиевые сплавы- Микродуговое оксидирование: Сплавы Al/Mg/Ti- Порошковое покрытие: Все металлы- Гальванизация: Медно-цинковые сплавы | С учетом потребностей., анодирование автомобильных деталей; гальваника для декоративных компонентов |
2.3 Точная обработка
На этом этапе уточняются размеры и формы.. Success depends on clamping strategies and parameter optimization:
2.3.1 Clamping Strategies for Different Part Types
Тип частично | Метод зажима | Точность | Вариант использования |
Thin-Walled Parts (<3мм) | Vacuum Suction Cup + Honeycomb Support Pad | Prevents deformation | Aluminum alloy laptop casings |
Irregular-Shaped Parts | 3D-Printed Custom Fixtures | Error <0.02мм | 5G base station cooling modules |
Multi-Process Parts | Zero-Point Positioning System | Repeat positioning <0.01мм | New energy vehicle motor housings |
2.3.2 Optimized Machining Parameters
Материал | Process Type | Feed per Tooth (мм) | Глубина разрезания (мм) | Скорость резки (м/мой) | Метод охлаждения |
Алюминиевый сплав | Грубая | 0.15-0.25 | 0.8-1.2 | N/a | Low-temperature compressed air + micro-lubrication |
Нержавеющая сталь | Отделка | N/a | Радиал <0.5 | 80-120 | Same as above |
2.4 Heat Treatment Strengthening
Heat treatment boosts mechanical properties. Use material-specific schemes:
Материал | Heat Treatment Scheme | Ключевые параметры | Результаты |
A380 Aluminum Alloy | T6 Solution Aging | 535±5°C for 8-12h; Quench transfer <30с | Tensile strength σb=320MPa; Elongation δ=8% |
ZAM4-1 Magnesium Alloy | T6 Artificial Aging | 415±5°C for 24h; Inert gas protection | Brinell hardness HB=90; Creep resistance ↓40% |
ZA27 Zinc Alloy | Возрастное упрочнение | 90-120°C for 4-8h; Температура < eutectic point | Rockwell hardness HRB=95; Размерная стабильность |
Critical Notes: Magnesium alloys need inert gas to avoid oxidation; Zinc alloys must not exceed eutectic temperature (causes melting).
2.5 Special Processing
For residual stress relief and sealing protection:
Цель | Методы | Параметры | Преимущества |
Остаточное снятие стресса | – Vibration Aging- Криогенное лечение | – Frequency 2-50kHz; Amplitude 15-50μm- -196°C liquid nitrogen for 48h | Fatigue life ×2-3 (алюминиевые сплавы); Prevents long-term deformation |
Sealing Protection | – Silicone Rubber Impregnation (VIPI)- PARYLENE Vapor Deposition | – Pressure resistance IP68- Film thickness 5-25μm | Waterproof/dustproof; Protects electronics (НАПРИМЕР., Корпуса датчиков) |
3. How to Control Quality in Die Casting Post-Processing?
Quality control ensures parts meet standards. Use the right tools and tests:
Quality Aspect | Testing Method | Standards/Requirements |
Точность размеров | Координировать измерительную машину (ШМ) | ГБ/т 6414 CT7 |
Air Tightness | HE High-Pressure Leak Detection | Leakage rate <1cm³/[email protected] |
Шероховатость поверхности | White Light Interferometer | Decorative surfaces: Ra≤0.8μm |
Адгезия покрытия | Grid Test + Tape Peeling | ASTM D3359 Method B |
Internal Defects | 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:
Дефект | Причина | Решение |
Усадка (X-ray cloud-like shadows) | Insufficient cooling during casting | Add cooling inserts; Extend holding time to 8-12s |
Peeling (разделение слоя) | 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 |
Деформация | Residual stress release | Manual aging treatment; Use calibration fixtures |
Низкая твердость (СПЧ<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:
Поступ-обработка шага | Cost Share | Cycle Share | Советы по оптимизации | Результаты |
Basic Treatment | 15-25% | 20-30% | Use automatic rolling grinding lines | Manpower saved by 70% |
Поверхностная обработка | 20-35% | 15-25% | Build coating recycling systems | Consumables reduced by 40% |
Точная обработка | 30-40% | 30-40% | Adopt turn-mill composite machining centers | Cycle time shortened by 50% |
Качественная проверка | 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
В Yigu Technology, Мы видим post-processing of die casting as the “value-adding bridge” between raw castings and high-quality parts. Наши данные показывают 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 Стандарты биосовместимости. By integrating automation (like AI inspection) and material-specific schemes, we help clients cut costs by 25% while improving part reliability.
7. Часто задаваемые вопросы: Common Questions About Post-Processing of Die Casting
1 квартал: Can all die casting materials use the same surface treatment?
Нет. Например, 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.
2 квартал: Why is quench transfer time critical for aluminum alloy heat treatment?
Алюминиевые сплавы (like A380) need fast quenching after solution treatment to trap strengthening elements. If transfer time exceeds 30 секунды, elements precipitate early, reducing tensile strength by up to 20%. We use automated quenching systems to keep transfer time <25 секунды.
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 (50-80М/мин для алюминия) 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%.