Die casting clip is a typical surface defect in the die casting process, which seriously affects the appearance quality and structural integrity of castings. It is mainly manifested as obvious delamination ou peeling on the casting surface—these defects not only reduce the product’s market competitiveness but may also cause safety hazards in high-precision application scenarios (such as automotive parts or electronic components). To help manufacturers effectively identify, prevent, and solve this problem, this article will systematically analyze the causes of die casting clip and provide practical solutions.
1. What Exactly Is Die Casting Clip? Key Characteristics and Harm
Antes de explorar soluções, é essencial compreender claramente a natureza do clipe de fundição sob pressão. Esta seção usa um definição + ferir estrutura para ajudar os leitores a compreender rapidamente a essência do defeito.
1.1 Definição central
Die casting clip refers to a surface flaw formed when metal materials (especially aluminum alloys) undergo abnormal bonding or separation during the die casting process. Its most obvious feature is that the casting surface appears as a layered structure—when touched or subjected to external force, the surface layer may peel off, exposing the inner metal structure. Unlike small scratches or stains, this defect is not a superficial issue but a sign of internal structural inconsistency.
1.2 Potential Harm
The impact of die casting clip on products goes far beyond appearance:
- Appearance failure: Delamination or peeling makes the casting unable to meet the surface quality requirements, leading to direct scrapping or rework.
- Structural weakness: The layered area becomes a stress concentration point. During use, it may crack or break under load, affecting the product’s service life.
- Production loss: Para peças produzidas em massa, even a small proportion of die casting clip defects can significantly increase production costs (including material waste, rework time, e custos de inspeção).
2. Root Causes of Die Casting Clip: Three Key Factor Categories
O clipe de fundição sob pressão não é causado por um único fator, mas pela interação do molde, processo de injeção, e gerenciamento de materiais. A tabela a seguir classifica as causas específicas de cada categoria, tornando mais fácil para os fabricantes localizar problemas.
| Categoria de fator | Causas Específicas | Mecanismo de formação de defeitos |
| Problemas Relacionados ao Molde | 1. Rigidez insuficiente do molde2. Folga excessiva entre peças deslizantes/emendadas3. Zonas locais de alta temperatura na cavidade | 1. Tremores de molde durante o enchimento de metal, causando fluxo irregular de metal e colagem em camadas.2. Gaps exceed the allowable range, and aluminum skin (molten metal residue) is embedded between layers, forming a “sandwich” structure.3. High temperature causes alloy to adhere to the mold surface; when the casting is ejected, the adhered layer is torn, leading to peeling. |
| Injection Process Problems | 1. Punch crawling phenomenon2. Disordered metal flow (due to improper sprue system design) | 1. Poor coordination between the injection punch and pressure chamber results in uneven injection speed—fast and slow flow areas form layered interfaces.2. Metal flows in an incorrect order; the first-filled metal layer solidifies early, and the later-filled metal cannot bond with it, forming delamination. |
| Material & Process Management | 1. Fluctuations in alloy chemical composition2. Unclean parting surfaces (residues of aluminum skin/flash) | 1. Changes in element content (Por exemplo, increased silicon or copper) enhance the alloy’s affinity with the mold, increasing adhesion and peeling risk.2. Residues on the parting surface are pressed into the new casting during mold clamping, becoming a barrier between metal layers. |
3. Targeted Solutions: From Prevention to Resolution
Aiming at the three major factor categories above, this section provides step-by-step solutions—covering mold optimization, process improvement, and material management—to help manufacturers fundamentally reduce the occurrence of die casting clip.
3.1 Mold Optimization: Eliminate Structural Hidden Dangers
Mold is the foundation of die casting. Unreasonable mold design or wear is one of the main causes of die casting clip. The following measures can effectively improve mold performance:
- Enhance mold rigidity: Tighten all mold components (such as guide pillars, parafusos, and templates) and add reinforcing ribs to key stress-bearing parts. This reduces mold jitter during high-pressure injection, ensuring stable metal flow.
- Adjust sliding part clearance: Use precision measuring tools (Por exemplo, feeler gauges) to check the gap between sliding/splicing parts. For aluminum alloy die casting, the gap should generally be controlled within 0.05-0.1milímetros; if it exceeds this range, repair or replace worn parts in time.
- Control cavity temperature: Use CAE simulation software to identify local high-temperature zones in the cavity. For these areas, add point cooling water channels or extend the local spraying time of the release agent to keep the cavity temperature uniform (avoiding overheating-induced adhesion).
3.2 Injection Process Improvement: Ensure Stable Metal Flow
The injection process directly determines the filling state of the metal liquid. Optimizing process parameters can avoid disordered flow and layered bonding:
- Solve punch crawling: Primeiro, check whether the punch and pressure chamber are worn (if the inner wall of the pressure chamber is scratched, it should be re-polished). Então, adjust the lubrication of the punch—use high-temperature resistant lubricating oil to ensure smooth movement and uniform injection speed.
- Reconstruct the sprue system: Use the “black oil trace method” to observe the actual metal flow sequence: apply black oil to the mold cavity, conduct a trial injection, and check the oil trace distribution. Based on the results, optimize the position and cross-sectional area of the inner gate to ensure that the metal fills the cavity synchronously (avoiding early solidification of local layers).
- Select suitable release agents: Usar special die-casting release agents (not general-purpose lubricants). Para ligas de alumínio, silicone-based or graphite-based release agents are recommended—they form a thin, uniform protective film between the metal and mold, reducing adhesion without affecting metal bonding.
3.3 Material & Process Management: Avoid Human-Caused Defects
Good material control and daily maintenance can prevent die casting clip caused by operational errors:
- Monitor alloy composition: Use spectral analysis equipment to test the chemical composition of the alloy before melting. Ensure that key elements (such as magnesium in aluminum alloys) are within the process range—fluctuations should not exceed ±0.1% to avoid increasing the alloy’s affinity with the mold.
- Clean the parting surface regularly: After each mold opening, use a high-pressure air gun or non-metallic scraper to remove flash and aluminum skin residues on the parting surface. Do not use hard tools (such as steel scrapers) to avoid scratching the mold surface (which may exacerbate adhesion).
4. Perspectiva da Yigu Technology sobre clipes de fundição sob pressão
Na tecnologia Yigu, we believe that solving die casting clip requires a “prevention-first” mindset rather than post-repair. Many manufacturers only focus on reworking defective parts but ignore the root causes—for example, ignoring mold gap wear or irregular release agent replacement. Na verdade, die casting clip is a “early warning signal” of the production system: it may indicate mold aging, process parameter drift, or inadequate operator training.
We recommend that manufacturers establish a sistema de rastreabilidade de defeitos: registre o horário da ocorrência, número do molde, e parâmetros de processo de cada defeito do clipe de fundição sob pressão. Através da análise de dados, encontrar a correlação entre defeitos e fatores (Por exemplo, “os defeitos aumentam quando a temperatura do molde excede 220°C”). Adicionalmente, realizar treinamento regular para operadores – deixe-os reconhecer as características de aparência do clipe de fundição sob pressão e dominar os métodos básicos de ajuste (como ajustar a dosagem do agente de liberação). Combinando a otimização técnica com a atualização da gestão, die casting clip can be controlled at a rate of less than 0.5%.
5. Perguntas frequentes: Perguntas comuns sobre clipe de fundição sob pressão
1º trimestre: Como distinguir o clipe de fundição sob pressão do descascamento de superfície comum?
Ordinary surface peeling is usually caused by external force (such as collision) and only affects the outermost layer; the peeled part is small and irregular. Die casting clip is a structural defect—its peeling layer is larger, has a regular shape (consistent with the mold cavity), and the inner surface of the peeled layer is smooth (indicating incomplete bonding during casting).
2º trimestre: Aumentar a pressão de injeção ajudará a reduzir o clipe de fundição sob pressão?
Não necessariamente. Moderately increasing the injection pressure can improve metal flow uniformity, but excessive pressure (exceeding the mold’s bearing capacity) will increase mold jitter and gap expansion, which may instead exacerbate die casting clip. The key is to match the injection pressure with the mold rigidity—for molds with insufficient rigidity, first strengthen the mold before adjusting the pressure.
3º trimestre: O clipe de fundição sob pressão pode ser reparado após a ocorrência?
Para peças não críticas (such as decorative components), small-area die casting clip can be repaired by welding (using the same alloy material) + moagem. No entanto, Para peças de porte de carga (such as engine brackets), repaired areas may still have structural hidden dangers, so it is recommended to scrap them directly. The most effective way is to prevent defects during production rather than relying on post-repair.