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Aluminum ADC12 (A380)

Aluminum ADC12 (A380) is a die-cast aluminum alloy offering good machinability, corrosion resistance, and castability, making it ideal for high-volume CNC finishing of automotive, electronic, and structural parts.

Introduction to Aluminum ADC12 (A380)

Aluminum ADC12 (A380) is a widely used die-casting aluminum alloy known for its excellent castability, good mechanical strength, and corrosion resistance. Also known as A380 in North America, it is extensively used in complex, high-volume parts where dimensional stability, thin wall capability, and cost-effectiveness are priorities.

In CNC machining, Aluminum ADC12 (A380) is typically used for finishing operations on cast parts or secondary machining of semi-finished die castings. It is ideal for housings, engine blocks, connectors, and structural components in the automotive, consumer electronics, and industrial sectors.

Chemical, Physical, and Mechanical Properties of Aluminum ADC12 (A380)

Chemical Composition (Typical)

Element	Composition Range (wt.%)	Key Role
Aluminum (Al)	80.0–87.0	Base element providing lightweight and corrosion resistance
Silicon (Si)	7.5–9.5	Enhances fluidity and wear resistance
Copper (Cu)	2.0–4.0	Increases strength and hardness
Magnesium (Mg)	≤0.3	Slightly improves strength and corrosion resistance
Zinc (Zn)	≤3.0	Provides dimensional stability
Iron (Fe)	≤1.3	Increases wear resistance, may affect ductility
Manganese (Mn)	≤0.5	Refines grain structure
Nickel (Ni)	≤0.5	Improves corrosion resistance in specific environments
Others	≤0.50	Residual elements

Physical Properties

Property	Value (Typical)	Test Standard/Condition
Density	2.74 g/cm³	ASTM B311
Melting Point	555–615°C	ASTM E299
Thermal Conductivity	96 W/m·K at 25°C	ASTM E1952
Electrical Conductivity	25% IACS at 20°C	ASTM B193
Coefficient of Expansion	21.5 µm/m·°C	ASTM E228
Specific Heat Capacity	963 J/kg·K	ASTM E1269
Elastic Modulus	71 GPa	ASTM E111

Mechanical Properties (As-Cast / Heat Treated)

Property	Value (Typical)	Test Standard
Tensile Strength	310 MPa (As-Cast)	ASTM B557
Yield Strength (0.2%)	160 MPa (As-Cast)	ASTM B557
Elongation	1.5–3%	ASTM B557
Hardness	80–90 HB	ASTM E10
Fatigue Strength	125 MPa	ASTM E466
Impact Resistance	Moderate	ASTM E23

Key Characteristics of Aluminum ADC12 (A380)

Excellent Castability and Thin-Wall Forming: ADC12 is designed for high-pressure die casting and supports intricate, thin-walled geometries with low shrinkage and good mold fill characteristics.

Moderate Mechanical Strength: With tensile strength up to 310 MPa in the as-cast condition, the A380 is suitable for light to medium-load-bearing components that require rigid structural performance.

Good Corrosion Resistance: Naturally, it forms a protective oxide layer, making it suitable for indoor and lightly corrosive environments. Additional coatings extend durability.

Poor Ductility and Weldability: Due to high silicon and copper content, ADC12 is not recommended for welding. Instead, mechanical fastening or post-casting machining is used.

Superior Dimensional Stability: Low thermal expansion and creep are ideal for high-precision electronic enclosures and heat-sensitive assemblies.

CNC Machining Challenges and Solutions for Aluminum ADC12 (A380)

Machining Challenges

Porosity in Cast Surfaces: Voids may affect tool engagement and surface finish.
Tool Wear: High silicon content leads to abrasive behavior and faster tool degradation.
Brittleness: Requires controlled feed and finish passes to avoid chipping or cracking.

Optimized Machining Strategies

Tool Selection

Parameter	Recommendation	Rationale
Tool Material	PCD or TiB₂-coated carbide tools	Provides abrasion resistance against silicon
Geometry	Positive rake, polished edge	Enhances chip flow and reduces edge chipping
Cutting Speed	150–300 m/min	Minimizes BUE and improves finish on cast skin
Feed Rate	0.10–0.25 mm/rev	Ensures consistency and prevents cracking
Coolant	Dry or minimum quantity lubrication (MQL)	Reduces thermal shock and oxidation

Aluminum ADC12 (A380) Cutting Parameters (ISO 513 Compliance)

Operation	Speed (m/min)	Feed (mm/rev)	Depth of Cut (mm)	Coolant Type
Roughing	150–200	0.15–0.25	1.5–3.0	Dry or MQL
Finishing	250–300	0.05–0.10	0.2–1.0	MQL or light mist

Surface Treatment for Aluminum ADC12 (A380) CNC Parts

Anodizing: Limited due to high silicon content, but achievable with specialized pre-treatment for light-duty protection.
Powder Coating: Preferred surface treatment, offering 60–120 µm thickness, high wear, and chemical resistance.
Electropolishing: Rarely applied due to silicon phase. Alternative polishing or blasting often preferred for ADC12.
Passivation: Often used in pre-coating steps to enhance adhesion.
Brushing: Used to smooth die-cast or CNC machined surfaces, often before coating.
Alodine Coating: Suitable for electronics casings to maintain conductivity while adding corrosion resistance.
UV Coating: Used on cosmetic panels for scratch resistance and color clarity.
Lacquer Coating: Transparent protection for cosmetic or branded products.