Die casting aluminum parts are widely used in automotive, Электроника, and hardware industries, but their raw surface often lacks protection, украшение, or specific functions. Die casting aluminum surface treatment solves this problem through systematic processes—yet many engineers struggle with choosing the right method. This article breaks down core processes, сравнения, and selection strategies to help you make informed decisions.
1. Why Is Pretreatment the Foundation of All Surface Treatments?
Pretreatment eliminates surface defects and contaminants, directly determining the quality of subsequent treatments. Skipping or rushing this step leads to coating peeling, uneven coloring, or poor corrosion resistance. Below is a detailed breakdown of key pretreatment steps:
| Pretreatment Step | Основная цель | Общие методы | Ключевые примечания |
| Обезжиривание | Remove grease, release agent residue | Solvent cleaning, alkaline degreasing, Ультразвуковая чистка | Choose methods based on contamination level (НАПРИМЕР., ultrasonic for heavy grease) |
| Oxide Film Removal | Eliminate natural thin oxide layer and slight surface metamorphism | Weak alkaline solution soaking | Avoid strong alkalis—they may etch the aluminum surface |
| Sanding/Descaling | Clear embedded mold sand or dirt from die casting | Manual sanding, mechanical sanding | Focus on areas with dense sand (НАПРИМЕР., gate or overflow grooves) |
| Deburring/Polishing | Remove burrs (at parting lines) и гладкие поверхности | Manual polishing, mechanical grinding | Over-polishing closes pores (hurts coating adhesion); under-polishing leaves burr defects |
| Sandblasting/Shot Blasting | Improve surface roughness (boost coating adhesion) | Abrasive particle spraying (глинозем, Стеклянные бусинки) | Uniform spraying is critical—avoid uneven roughness |
Special Note for Porosity: Использовать impregnation (fill tiny pores with resin or wax) to improve air tightness—this is a must for subsequent dense treatments like electroplating.
2. Protective Treatments: Which One Fits Your Corrosion Resistance Needs?
Protective treatments extend the service life of die casting aluminum parts. Below is a comparison of the most common methods to help you choose:
| Тип лечения | Принцип работы | Преимущества | Ограничения | Ideal Application Scenarios |
| Chemical Conversion Film | Chemical reaction forms a thin protective film (НАПРИМЕР., хромат, phosphate) | Бюджетный, simple process; good pre-coating base | Poor long-term corrosion resistance | Short-term protection (НАПРИМЕР., temporary storage) or pre-coating for spraying |
| Анодирование | Electrochemical reaction generates a thick alumina film (жесткий, пористый) | Высокая твердость (износостойкий); Отличная коррозионная стойкость | Die castings’ high porosity causes film blistering; poor dyeing effect | Parts needing high corrosion resistance (НАПРИМЕР., Морское оборудование, открытые светильники) |
| Гальванизация | Electrolysis deposits metal layers (хром, никель) на поверхности | Dual benefits: коррозионная стойкость + украшение; Высокая твердость (хромирование) | Complex pretreatment; strict control of chemical solutions (to avoid pore defects) | Decorative-cum-protective parts (НАПРИМЕР., Автомобильная отделка, bathroom fixtures) |
| Распыление | Apply coatings (пудра, жидкость, electrophoretic) на поверхности | Rich colors; good coverage (fits complex shapes); powder coating is eco-friendly | High-temperature curing (needs temperature control to prevent deformation) | Части со сложными формами (НАПРИМЕР., Электронные корпуса, Кухонная техника) |
3. Декоративный & Functional Treatments: Meet Special Requirements
Beyond protection, decorative treatments boost product value, пока functional treatments enable specific performance.
3.1 Decorative Treatments: From Matte to Metallic Shine
| Уход | Effect Description | Key Process | Ограничения | Target Products |
| Polished/Brushed | Блестящий (полированный) or textured (почистота: straight grain, studded grain) поверхность | Механическое шлифование + полировка | Requires high initial surface quality | High-grade hardware (НАПРИМЕР., Кран ручки, luxury electronic casings) |
| Sandblasting Effect | Uniform matte surface | Fine abrasive spraying | Cannot hide major surface defects | Parts needing low-gloss appearance (НАПРИМЕР., Промышленные панели управления) |
| Анодирование + Раскраска | Окрашивание (organic dyes) or electrolytic coloring (бронза, черный) after sulfuric acid anodizing | Anodizing → coloring → sealing | Die castings’ porosity limits dyeing uniformity | Semi-decorative parts (НАПРИМЕР., medium-grade furniture hardware) |
| Vacuum Coating (Pvd) | Deposits metal/ceramic films (золото, rose gold, титан) via physical vapor deposition | High-vacuum environment + ion sputtering | Requires highly smooth substrate surface | High-end decorative parts (НАПРИМЕР., Рамки смартфонов, Роскошные часы) |
3.2 Functional Treatments: Tailored to Performance Needs
| Functional Requirement | Метод лечения | Примеры применения |
| Проводимость | Electroplating copper/silver; conductive oxidation | Электронные разъемы, electromagnetic shielding parts |
| Изоляция | Анодирование (thick film); polyurethane insulating paint coating | Motor components, electronic insulation brackets |
| Устойчивость к истиранию | Hard anodizing (film thickness: 20-50мкм); PVD durable film; wear-resistant spray coating | Движущиеся части (НАПРИМЕР., передачи), цилиндры, pneumatic components |
4. 4 Key Factors to Choose the Right Surface Treatment Process
Choosing a process is not about “the best” but “the most suitable.” Consider these four factors:
- Final Requirements: Clarify priorities—Is it corrosion resistance (НАПРИМЕР., outdoor parts need anodizing), украшение (НАПРИМЕР., luxury parts need PVD), или функциональность (НАПРИМЕР., connectors need conductive plating)?
- Свойства материала: Alloy composition and surface quality matter. Например, АДК12 алюминиевый сплав (high silicon content) may affect electroplating uniformity; porous surfaces require impregnation first.
- Расходы & Экологическое дружелюбие: Balance budget and regulations. Хромирование (high cost, токсичный) is being replaced by eco-friendly options like powder coating or PVD.
- Production Scale: Автоматические процессы (НАПРИМЕР., electrophoresis, Порошковое покрытие) suit mass production; manual polishing/PVD fits small-batch high-end products.
Yigu Technology’s Perspective on Die Casting Aluminum Surface Treatment
В Yigu Technology, Мы верим pretreatment precision and process matching are the keys to successful die casting aluminum surface treatment. С годами, we’ve seen many projects fail due to neglected porosity (no impregnation) or mismatched treatments (НАПРИМЕР., using anodizing for highly porous ADC12 parts). We advocate a “test-first” approach: conduct small-batch trials to verify pretreatment effectiveness and coating adhesion before mass production. Кроме того, as environmental regulations tighten, we prioritize eco-friendly processes like powder coating and chrome-free conversion films—helping clients meet both performance and sustainability goals.
Часто задаваемые вопросы (Часто задаваемые вопросы)
- Q.: Why do die casting aluminum parts often have blistering during anodizing?
А: The main cause is high surface porosity of die castings. During anodizing, air or moisture in pores expands under electrolysis, leading to blistering. Solve this by adding an impregnation step before anodizing to seal pores.
- Q.: Which is more cost-effective for mass-produced outdoor aluminum parts—anodizing or powder coating?
А: Powder coating is more cost-effective. It has lower equipment investment than anodizing, faster curing speed (suitable for mass production), and excellent outdoor weather resistance. Anodizing is better only if ultra-high hardness is required.
- Q.: Can vacuum coating (Pvd) be applied to die casting aluminum parts with rough surfaces?
А: Нет. PVD requires a highly smooth substrate (Ra ≤ 0.2μm). Rough surfaces will cause uneven film deposition, affecting both appearance and wear resistance. Pre-treat rough parts with fine polishing or sandblasting to smooth the surface first.