Vacuum Die Casting vs. Squeeze Casting Mechanical Properties Compared

Meta Description: Vacuum die casting vs squeeze casting: comprehensive comparison of mechanical properties, porosity levels, tensile strength, and applications for aluminum precision parts. Expert guide for OEM manufacturers.

When sourcing custom aluminum die casting services for high-performance applications, engineers and procurement managers frequently face a critical decision: vacuum die casting or squeeze casting? Both advanced high pressure die casting (HPDC) variants offer superior mechanical properties compared to conventional die casting, but their distinct process characteristics deliver different performance outcomes.

This comprehensive technical comparison examines the critical mechanical properties—tensile strength, yield strength, elongation, porosity levels, and fatigue resistance—to help you select the optimal OEM die casting process for automotive, aerospace, and industrial applications.

What is Vacuum Die Casting?

Vacuum die casting is an advanced aluminum die casting process that evacuates air and gases from the mold cavity before molten metal injection. By creating a vacuum environment (typically 50-250 mbar), this method dramatically reduces gas porosity and eliminates trapped air pockets that compromise structural integrity.

Key process characteristics: 

• Vacuum levels: 50-250 mbar absolute pressure
• Ideal for thin-wall precision casting (1.5-3mm) 
• Cycle times: 20-40% longer than conventional HPDC 
• Typical alloys: A380, A383, ADC12, AlSi10Mg

What is Squeeze Casting?

Squeeze casting (also called liquid forging or pressurization casting) combines die casting and forging principles. Molten metal is poured into an open die and solidified under extremely high pressure (50-150 MPa), which eliminates shrinkage porosity and produces a fine, uniform microstructure.

Key process characteristics: 

• Applied pressure: 50-150 MPa (5-15× higher than HPDC)
• Slow, controlled metal introduction 
• Excellent for thick-wall structural components 
• Superior heat treatability compared to vacuum die casting

Tensile Strength (UTS)

Analysis: Squeeze casting consistently achieves higher tensile strength due to: 

• Elimination of micro-shrinkage 
• Refined eutectic silicon morphology
• Higher density (2.69 vs 2.65 g/cm³)

Yield Strength (0.2% Offset)

Vacuum die casting yield strengths typically range from 150-190 MPa for A380 alloy while squeeze casting achieves 180-240 MPa—a 20-25% improvement. This difference is critical for: 

• Safety-critical automotive components (steering knuckles, suspension arms)
• Aerospace structural parts requiring predictable deformation behavior
• Industrial machinery under cyclic loading 

Elongation and Ductility

This is where squeeze casting demonstrates significant advantages: 

• Vacuum die casting elongation: 2-5% 
• Squeeze casting elongation: 8-15%

The higher ductility makes squeeze casting ideal for components requiring post-casting forming or those subjected to impact loads. However, vacuum die casting offers sufficient ductility for most housings, covers, and non-structural parts.

Porosity Levels: The Decisive Factor

Vacuum Die Casting Porosity: 

• Gas porosity: <1% by volume 
• Typical range: 0.5-2% 
• Limited improvement in shrinkage porosity 
• Good for pressure-tight applications up to 50 bar

Squeeze Casting Porosity: 

Total porosity: <0.5% by volume 

Virtually zero gas and shrinkage porosity Achievable density: >99.8% 

Pressure-tight beyond 200 bar

Bottom line: For zero-porosity casting requirements, squeeze casting is superior. For low-porosity casting where cycle time matters, vacuum die casting provides the best compromise.

When to Specify Vacuum Die Casting

Choose vacuum die casting services for:

1. Thin-wall aluminum castings (<3mm wall thickness)

2. Large-volume production (>50,000 parts annually)

3. Cosmetic surfaces requiring minimal post-processing

4. Electronics housings and telecommunication equipment

5. Budget-sensitive projects where premium properties aren't critical

6. Parts requiring complex geometries with undercuts

Typical applications: EV battery housings, LED lighting fixtures, laptop frames, 5G antenna boxes.

When to Specify Squeeze Casting

Specify squeeze casting for:

1. Structural die casting components in automotive suspension

2. High-performance aluminum parts requiring T6 heat treatment

3. Safety-critical applications (crashworthiness, high fatigue loads)

4. Hydraulic/pneumatic components requiring absolute pressure tightness

5. Medium production volumes (5,000-30,000 parts)

6. Thick-wall castings (>5mm) with uniform properties

Typical applications: Electric vehicle chassis parts, aerospace fittings, military components, premium bicycle frames.

Tooling Investment 

• Vacuum die casting mold: $25,000-$60,000 
• Squeeze casting mold: $35,000-$80,000 (+40% premium)
  

Piece Price Factors 

• Vacuum die casting: Cycle time 30-90 seconds; moderate machine wear 
• Squeeze casting: Cycle time 120-300 seconds; higher energy consumption

Total cost of ownership (TCO) insight: While squeeze casting has 15-25% higher piece prices, it often eliminates secondary operations (HIP, impregnation, welding repair)

required for vacuum die casting parts in critical applications.

Heat Treat Response

Squeeze casting parts can be fully T6 heat treated, achieving 

T6 yield strength: 280-320 MPa (A356) 

Improved fatigue life: +40-60%

Vacuum die casting is typically limited to T5 aging due to blistering risk from residual microporosity expanding at solution temperatures.

Weldability and Machining

Both processes offer excellent machinability, but squeeze casting provides superior

weldability due to lower oxide film content and absence of gas pockets that cause weld rejections.

Professional custom die casting manufacturers should provide:

For vacuum die casting quality control: 

• X-ray inspection per ASTM E505 
• Pressure decay testing 
• Porosity analysis via metallography Tensile testing from each lot

For squeeze casting quality control: 

• 100% ultrasonic testing (C-scan recommended)
• Density measurement via Archimedes method 
• Enhanced mechanical property testing including fatigue testing
• Fracture toughness evaluation for safety-critical parts

For OEM manufacturers and product designers sourcing from precision die casting companies, the choice between vacuum die casting and squeeze casting ultimately depends on your application's criticality:

• Vacuum die casting delivers excellent mechanical properties with minimal porosity at competitive costs for high-volume, non-safety-critical components.
• Squeeze casting provides forging-grade properties in a near-net-shape process, justifying its premium for structural, safety-critical, and high-performance applications.

Both processes represent significant advancements over conventional high pressure die casting, enabling custom aluminum casting solutions that meet stringent modern engineering requirements.

As an ISO 9001 certified die casting factory specializing in both vacuum die casting and squeeze casting for international markets, we provide:

• Free DFM analysis and mechanical property consultation
• PPAP documentation for automotive clients 
• Prototype casting in 2-3 weeks
• Competitive pricing for US, European, and Australian OEMs

Contact our engineering team today for a detailed quote on your next precision aluminum casting project.

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Q: Can vacuum die casting achieve zero porosity?

A: While vacuum die casting dramatically reduces gas porosity to <1%, achieving absolute zero porosity is technically challenging. For true zero-porosity

requirements, squeeze casting is recommended.

Q: Is squeeze casting always better for mechanical properties?

A: For thick-wall parts requiring optimal mechanical properties, yes. However, for thin-wall components where cycle time and cost are priorities, vacuum die casting often provides the best balance.

Q: Which process is better for automotive electric vehicle components?

A: EV battery housings typically use vacuum die casting for thin trays, while Structural die castings like chassis nodes increasingly adopt squeeze casting for crash performance.

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