Aluminum 2011

Aluminum 2011 is a free-cutting aluminum alloy designed for CNC turning of high-precision, high-volume parts requiring tight tolerances and excellent surface finishes—best suited for non-structural, corrosion-protected applications.

Introduction to Aluminum 2011

Aluminum 2011 is a high-machinability, free-cutting aluminum alloy known for its excellent chip formation and fast cycle times in high-speed CNC operations. Often referred to as the "standard for machinability" among aluminum alloys, it’s ideal for precision-turned parts requiring tight tolerances and high-volume production.

Thanks to its lead content and excellent surface finish characteristics, Aluminum 2011 is widely used in CNC machining of connectors, fittings, shafts, bushings, and precision electronic and automotive components.

Chemical, Physical, and Mechanical Properties of Aluminum 2011

Chemical Composition (Typical)

Element	Composition Range (wt.%)	Key Role
Aluminum (Al)	Balance	Lightweight base metal with good thermal properties
Copper (Cu)	5.0–6.0	Increases strength and hardness
Bismuth (Bi)	0.2–0.6	Enhances machinability and chip breaking
Lead (Pb)	0.2–0.6	Improves free-cutting properties
Iron (Fe)	≤0.7	Residual element
Silicon (Si)	≤0.4	Residual element
Zinc (Zn)	≤0.3	Residual element
Others	≤0.15 (total)	Residual elements

Physical Properties

Property	Value (Typical)	Test Standard/Condition
Density	2.82 g/cm³	ASTM B311
Melting Point	535–645°C	ASTM E299
Thermal Conductivity	140 W/m·K at 25°C	ASTM E1952
Electrical Conductivity	39% IACS at 20°C	ASTM B193
Coefficient of Expansion	23.2 µm/m·°C	ASTM E228
Specific Heat Capacity	875 J/kg·K	ASTM E1269
Elastic Modulus	70 GPa	ASTM E111

Mechanical Properties (T3 Temper)

Property	Value (Typical)	Test Standard
Tensile Strength	330 MPa	ASTM E8/E8M
Yield Strength (0.2%)	275 MPa	ASTM E8/E8M
Elongation	≥10%	ASTM E8/E8M
Hardness	95 HB	ASTM E10
Fatigue Strength	100 MPa	ASTM E466
Impact Resistance	Moderate	ASTM E23

Key Characteristics of Aluminum 2011

Exceptional Machinability: Aluminum 2011 is rated 100% machinability (benchmark standard), delivering excellent chip control, minimal tool wear, and high-speed production—ideal for CNC turned parts with complex geometries.

Outstanding Surface Finish: Generates clean, burr-free surfaces even at high feed rates, with typical finishes in the Ra ≤0.8 µm range in precision lathe operations.

Moderate Strength with Good Dimensional Stability: Offers yield strength up to 275 MPa in T3 condition with low warping or residual stress—suitable for tightly toleranced fittings and connectors.

Poor Weldability and Corrosion Resistance: Lead and copper content reduce weldability and corrosion resistance; parts typically receive protective coatings after machining.

Not Suitable for Structural or Load-Bearing Applications: Due to low corrosion resistance and fatigue life, 2011 is reserved for non-structural applications requiring dimensional precision and repeatability.

CNC Machining Challenges and Solutions for Aluminum 2011

Machining Challenges

Lead Content Considerations: May require special handling for environmental or medical applications due to lead content.
Limited Weldability: Welding is discouraged due to hot cracking risk and lead vapor.
Post-Machining Protection Needed: Susceptible to oxidation if left untreated.

Optimized Machining Strategies

Tool Selection

Parameter	Recommendation	Rationale
Tool Material	Uncoated or TiN-coated carbide	Enhances finish and chip breaking
Geometry	Sharp point, high rake angle	Facilitates chip control and lowers tool load
Cutting Speed	250–500 m/min	Enables high-speed turning and drilling
Feed Rate	0.10–0.35 mm/rev	Maintains tight tolerance and smooth finish
Coolant	Light oil mist or dry cutting	Reduces chip buildup and improves visibility

Aluminum 2011 Cutting Parameters (ISO 513 Compliance)

Operation	Speed (m/min)	Feed (mm/rev)	Depth of Cut (mm)	Coolant Pressure (bar)
Roughing	250–400	0.20–0.35	1.5–3.0	Dry or mist
Finishing	400–500	0.05–0.10	0.2–0.8	Mist/lubrication optional

Surface Treatment for Aluminum 2011 CNC Parts

Anodizing: Limited success due to high copper content. May show non-uniform coloration unless properly pre-treated.
Powder Coating: Adds corrosion protection and aesthetics with 60–100 µm coating thickness.
Electropolishing: Enhances already high surface finish to ≤0.2 µm Ra. Typically used on visible or mechanical sliding surfaces.
Passivation: Applied for surface cleaning and corrosion inhibition before further coating.
Brushing: Prepares part for painting or powder coating; common for cosmetic or industrial panels.
Alodine Coating: Used for temporary corrosion resistance and conductivity; especially for electrical applications.
UV Coating: Adds a thin protective layer for high-gloss, consumer-facing parts.
Lacquer Coating: Clear coatings improve oxidation resistance and cosmetic appeal in high-turnover consumer goods.