What Does Effective Post-Processing of Die Casting Involve?

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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, 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, planicidade, 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) primeiro, then precision tasks (como moer). 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 produçãoRecommended MethodPrincipais vantagensParâmetros Críticos
Produção em massaAutomatic Stamping & CisalhamentoAlta eficiência (1000+ peças/hora); Flat cross-sectionsRetain 1-2mm margin to protect the part body; Cut angle <5°
Small-Medium BatchesGrinding Wheel/Diamond Saw CuttingFlexível (works for odd-shaped parts); Low equipment costUse diamond blades for aluminum alloys to reduce burrs
High-Precision PartsFive-Axis Laser CuttingNo deformation risk; Corta formas complexasLaser power: 500-1000C; Velocidade de corte: 100-300mm/min

Observação: Usar Corte frio for aluminum-magnesium alloys to avoid heat-affected zones that weaken the part.

2.2 Surface Treatment Combinations

Surface treatment improves appearance, Resistência à corrosão, e funcionalidade. Choose based on material and part use:

Treatment LevelTécnicasPrincipais especificaçõesMateriais adequadosBenefícios
Basic TreatmentVibration Grinding (ceramic medium + alkaline solution)- Jato de areia (ASTM B243 ALMEN standard)- Chemical Degreasing (ultrasound-assisted)Deburrs edges- Ra=3.2-6.3μm (jato de areia)- Contact angle <5° (Desentando)All die casting metalsPrepares surfaces for advanced treatments; Removes oil/dirt
Advanced Treatment– Anodizando- Micro-Arc Oxidation- Revestimento em pó- EletroplataçãoCorrosion resistance ×3 (Anodizando)- Hardness HV≥800 (micro-arc oxidation)- Teste de pulverização de sal >1000h (revestimento em pó)- Gloss 90GU (Eletroplatação)– Anodizando: Ligas de alumínio- Micro-arc oxidation: Al/Mg/Ti alloys- Revestimento em pó: Todos os metais- Eletroplatação: Copper/zinc alloysTailored to needs—e.g., anodizing for automotive parts; electroplating for decorative components

2.3 Usinagem de precisão

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 peçaMétodo de fixaçãoPrecisãoCaso de uso
Thin-Walled Parts (<3milímetros)Vacuum Suction Cup + Honeycomb Support PadPrevents deformationAluminum alloy laptop casings
Irregular-Shaped Parts3D-Printed Custom FixturesError <0.02milímetros5G base station cooling modules
Multi-Process PartsZero-Point Positioning SystemRepeat positioning <0.01milímetrosNew energy vehicle motor housings

2.3.2 Optimized Machining Parameters

MaterialTipo de processoAlimentação por dente (milímetros)Profundidade de corte (milímetros)Velocidade de corte (m/meu)Cooling Method
Liga de alumínioDesbaste0.15-0.250.8-1.2N / DLow-temperature compressed air + micro-lubrication
Aço inoxidávelAcabamentoN / DRadial <0.580-120Igual ao acima

2.4 Heat Treatment Strengthening

Heat treatment boosts mechanical properties. Use material-specific schemes:

MaterialHeat Treatment SchemeParâmetros -chaveResultados
A380 Aluminum AlloyT6 Solution Aging535±5°C for 8-12h; Quench transfer <30éTensile strength σb=320MPa; Elongation δ=8%
ZAM4-1 Magnesium AlloyT6 Artificial Aging415±5°C for 24h; Inert gas protectionBrinell hardness HB=90; Creep resistance ↓40%
ZA27 Zinc AlloyEndurecimento por idade90-120°C for 4-8h; Temperatura < eutectic pointRockwell hardness HRB=95; Estabilidade dimensional

Notas Críticas: 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:

PropósitoTécnicasParâmetrosBenefícios
Alívio do estresse residualVibration Aging- Tratamento criogênicoFrequency 2-50kHz; Amplitude 15-50μm- -196°C liquid nitrogen for 48hFatigue life ×2-3 (ligas de alumínio); Prevents long-term deformation
Sealing ProtectionSilicone Rubber Impregnation (VIPI)- PARYLENE Vapor DepositionPressure resistance IP68- Film thickness 5-25μmWaterproof/dustproof; Protects electronics (Por exemplo, Altas do sensor)

3. How to Control Quality in Die Casting Post-Processing?

Quality control ensures parts meet standards. Use the right tools and tests:

Quality AspectTesting MethodStandards/Requirements
Precisão dimensionalMáquina de medição de coordenadas (Cmm)GB/T. 6414 CT7
Air TightnessHE High-Pressure Leak DetectionLeakage rate <1cm³/[email protected]
Rugosidade da superfícieWhite Light InterferometerDecorative surfaces: Ra≤0.8μm
Adesão de revestimentoGrid Test + Tape PeelingASTM D3359 Method B
Defeitos InternosX-Ray Fluorescence + CT ScanningISO 17636-1 Level B

4. How to Fix Common Post-Processing Defects?

Defects like shrinkage or pores can be resolved with targeted solutions:

DefeitoCausaSolução
Encolhimento (X-ray cloud-like shadows)Insufficient cooling during castingAdd cooling inserts; Extend holding time to 8-12s
Peeling (Separação de camada)Large mold temperature gradientUse mold temperature controller to keep inlet/outlet temp difference <5° c
Pores (tiny air bubbles)Trapped air during castingAdd more exhaust grooves; Adjust backpressure valve
DeformaçãoResidual stress releaseManual aging treatment; Use calibration fixtures
Baixa dureza (CDH<48)Inadequate heat treatmentLaser 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:

Etapa de pós-processamentoCost ShareCycle ShareDicas de otimizaçãoResultados
Basic Treatment15-25%20-30%Use automatic rolling grinding linesManpower saved by 70%
Tratamento de superfície20-35%15-25%Build coating recycling systemsConsumables reduced by 40%
Usinagem de precisão30-40%30-40%Adopt turn-mill composite machining centersCycle time shortened by 50%
Inspeção de qualidade5-10%5-10%Replace manual checks with AI visual inspectionMissed detection rate <0.1%

6. Yigu Technology’s Perspective on Post-Processing of Die Casting

Na tecnologia Yigu, nós vemos post-processing of die casting as the “value-adding bridge” between raw castings and high-quality parts. Nossos dados mostram 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 + gravação a laser para atender à ISO 10993 Padrões de biocompatibilidade. Ao integrar a automação (como inspeção de IA) e esquemas específicos de materiais, ajudamos os clientes a reduzir custos 25% enquanto melhora a confiabilidade das peças.

7. Perguntas frequentes: Common Questions About Post-Processing of Die Casting

1º trimestre: Can all die casting materials use the same surface treatment?

Não. Por exemplo, anodização só funciona em ligas de alumínio (forma uma camada de óxido), enquanto a oxidação por microarco é melhor para ligas de Al/Mg/Ti. As ligas de zinco são frequentemente galvanizadas para decoração, mas o revestimento em pó funciona para a maioria dos metais – sempre combine o tratamento com o material e a função da peça.

2º trimestre: Why is quench transfer time critical for aluminum alloy heat treatment?

Ligas de alumínio (como A380) precisam de têmpera rápida após o tratamento com solução para reter os elementos de fortalecimento. If transfer time exceeds 30 segundos, elements precipitate early, reducing tensile strength by up to 20%. We use automated quenching systems to keep transfer time <25 segundos.

3º trimestre: 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 alumínio) 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%.

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