MIC 6 aluminum is a precision cast aluminum plate specifically engineered for applications requiring exceptional flatness, dimensional stability, and uniform mechanical properties. Unlike rolled aluminum plates, MIC 6 is produced through a controlled casting process, resulting in minimal residual stress and excellent machinability. Its outstanding surface finish and consistent properties make it a preferred choice for precision tooling, fixtures, jigs, and machine bases. This article explores what MIC 6 aluminum is, its key characteristics and properties, and the diverse applications where it excels.
What Is MIC 6 Aluminum?
MIC 6 aluminum is a precision cast aluminum plate originally developed by Alcoa to meet the needs of industries requiring extremely flat, dimensionally stable, and stress-free aluminum stock. Unlike rolled aluminum plate such as 6061 or 7075, MIC 6 is produced through a continuous cast process, which minimizes internal stresses and produces a very uniform grain structure.
Key Characteristics
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Origin: Developed by Alcoa as a precision cast plate
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Manufacturing Method: Cast rather than rolled, resulting in minimal residual stress
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Uniform Properties: Excellent flatness, consistent thickness, and high dimensional stability
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Finish: Supplied with a fine machined surface finish, reducing preparation time
MIC 6 Aluminum in Precision Applications
MIC 6 aluminum plate is widely used in tooling, fixtures, jigs, machine bases, and precision components where surface stability and tight tolerances are critical. Its stress-relieved and cast structure allows for less warping during machining compared with rolled products.
MIC 6 Aluminum vs 6061 Aluminum
| Property/Feature | MIC 6 Aluminum (Cast Plate) | 6061 Aluminum (Rolled Plate) |
| Flatness | Exceptional; precision cast with high tolerance | Moderate; may require surface machining |
| Dimensional Stability | Excellent; minimal internal stress | Lower; can warp after machining |
| Machinability | Very good due to uniform grain and stress-free structure | Good, but residual stress may affect complex machining |
| Strength | Moderate (not as strong as 6061) | Higher structural strength |
| Applications | Tooling plates, jigs, fixtures, precision parts | Structural and general engineering parts |
In short, MIC 6 aluminum excels where flatness, stability, and consistent machinability are more important than high structural strength, making it ideal for precision manufacturing environments.
Chemical Composition of MIC 6 Aluminum
MIC 6 aluminum is not a single standardized alloy grade, but a proprietary precision cast aluminum plate designed to deliver high flatness, dimensional stability, and uniform mechanical properties. Its composition is optimized to achieve excellent machinability and minimal internal stress rather than maximum strength.
Typical Chemical Composition (Reference Data)
| Element | Content (%) |
| Aluminum | Balance |
| Silicon | 0.4–0.7 |
| Iron | 0.3 |
| Copper | 0.25 |
| Manganese | 0.1 |
| Magnesium | 0.1 |
| Zinc | 0.1 |
| Titanium | 0.06 |
Note: MIC 6 contains low levels of alloying elements compared to high-strength rolled aluminum alloys.
MIC 6 Aluminum vs 6061 & 7075 Aluminum – Composition Comparison
| Element / Alloy | MIC 6 (Cast Plate) | 6061 (Rolled Alloy) | 7075 (Rolled Alloy) |
| Main Alloying Elements | Low levels of Si, Cu, Mg for machinability | Mg (0.8–1.2%), Si (0.4–0.8%) for strength + corrosion resistance | Zn (5.1–6.1%), Mg (2.1–2.9%), Cu (1.2–2.0%) for ultra-high strength |
| Aluminum Content | Balance | Balance | Balance |
| Silicon (%) | 0.4–0.7 | 0.4–0.8 | ≤0.4 |
| Magnesium (%) | 0.1 | 0.8–1.2 | 2.1–2.9 |
| Zinc (%) | 0.1 | ≤0.25 | 5.1–6.1 |
| Copper (%) | 0.25 | ≤0.25 | 1.2–2.0 |
| Strength Focus | Stability & machinability | Strength & corrosion resistance | Ultra-high strength |
Key Takeaways
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MIC 6 is engineered for stability, flatness, and machinability, not maximum strength.
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6061 offers a balance of strength, corrosion resistance, and weldability.
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7075 is optimized for ultra-high strength and aerospace-grade performance but has lower corrosion resistance.
Physical Properties of MIC 6 Aluminum
MIC 6 aluminum is a precision cast aluminum plate designed to offer exceptional flatness, dimensional stability, and uniform mechanical properties. Unlike rolled alloys (such as 6061 or 7075), MIC 6 is optimized for stability and machinability rather than maximum strength.
| Property | MIC 6 Aluminum (Typical) | Notes |
| Density | ~2.70 g/cm³ (0.097 lb/in³) | Similar to most aluminum alloys |
| Flatness Tolerance | As tight as ±0.127 mm/m (±0.005 in/ft) or better (factory standard) | Significantly better than rolled aluminum plates |
| Dimensional Stability | Very high — low internal stress | Excellent for precision machining, jigs, and fixtures |
| Damping Capacity | Superior vibration dampening compared to rolled aluminum | Ideal for molds, tooling, and CNC bases |
| Thermal Conductivity | ~138 W/m·K (at 20 °C) | Slightly lower than 6061 due to cast structure |
| Electrical Conductivity | ~34% IACS (≈19.7 MS/m) | Moderate, suitable for general industrial use |
| Coefficient of Thermal Expansion (CTE) | ~23.6 µm/m·°C | Comparable to 6061 |
| Service Temperature Range | Up to ~150 °C (302 °F) for best stability | Above this, dimensional stability may decrease |
Highlights
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Density & Conductivity: Nearly the same as conventional aluminum alloys but with lower internal stress.
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Flatness & Stability: MIC 6 surpasses rolled aluminum plates in flatness tolerance and dimensional stability, making it ideal for molds, fixtures, machine bases, and precision tools.
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Thermal & Electrical Properties: Good heat transfer and moderate electrical conductivity, suitable for precision industrial applications.
Mechanical Properties of MIC 6 Aluminum
MIC 6 aluminum is engineered primarily for flatness and dimensional stability, not maximum strength. Its cast structure and stress-relieved manufacturing process make it ideal for applications such as tooling, jigs, fixtures, and machine bases, where stability and machinability outweigh tensile performance.
| Property | MIC 6 (Typical) | 6061-T6 (Reference) | Notes |
| Tensile Strength (MPa) | ~170 MPa (25 ksi) | ~310 MPa (45 ksi) | MIC 6 has about half the tensile strength of 6061-T6 |
| Yield Strength (MPa) | ~120 MPa (17 ksi) | ~276 MPa (40 ksi) | Lower yield due to cast structure |
| Hardness (Brinell HB) | ~65 HB | ~95 HB | MIC 6 is softer, enhancing machinability |
| Elongation (%) | ~3–4% | ~12% | Limited ductility; best used in non-structural applications |
| Elastic Modulus (GPa) | ~71 GPa | ~69 GPa | Comparable stiffness despite cast form |
Key Takeaways
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Strength vs. Stability: MIC 6 offers much lower tensile and yield strength than 6061-T6, but its stress-relieved, precision-cast structure delivers unmatched flatness and dimensional stability.
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Machinability: Its relatively low hardness and internal stress make it easy to machine to tight tolerances without warping.
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Application Focus: Best for fixtures, molds, and tooling plates rather than high-stress structural components.
Thermal Properties of MIC 6 Aluminum
MIC 6 aluminum is engineered for dimensional stability under thermal variations, making it ideal for precision tooling, molds, and fixtures. Its cast and stress-relieved structure provides predictable thermal behavior.
| Property | MIC 6 (Typical) | Notes |
| Thermal Conductivity (W/m·K) | ~121 | Moderate conductivity; lower than 6061-T6 (~167 W/m·K) but sufficient for controlled thermal environments |
| Coefficient of Thermal Expansion (CTE, µm/m·°C) | ~23 ×10⁻⁶ | Very low and uniform expansion reduces distortion under temperature changes |
| Operating Temperature Range (°C) | -40 to 150 | Maintains flatness and stability; avoid prolonged exposure above 150°C to prevent microstructural changes |
Key Takeaways
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Thermal Stability: MIC 6 exhibits minimal dimensional changes with temperature, critical for high-precision tooling and inspection plates.
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Comparison with Rolled Aluminum: While 6061 or 7075 may have higher thermal conductivity, they are more prone to warping under thermal cycles due to residual stresses.
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Applications: Ideal for molds, jigs, fixtures, and precision equipment where flatness and thermal stability outweigh ultimate strength.
This makes MIC 6 a premium choice for precision machining and tooling applications, especially where heat exposure and dimensional consistency are critical.
Common Forms and Tempers of MIC 6 Aluminum
MIC 6 aluminum is primarily supplied as cast plates and thick slabs with a wide range of thicknesses, typically used for flat, high-stability applications. Common forms include:
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Flat plates: Standard and precision-ground surfaces for tooling and fixture applications
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Thick slabs: For large molds or structural components requiring dimensional stability
Tempers
Unlike rolled aluminum alloys (e.g., 6061-T6, 7075-T651), MIC 6 does not use “T” temper designations. Instead, the entire casting undergoes:
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Stress relief: Eliminates internal stresses from casting, providing exceptional flatness and dimensional stability
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Precision machining compatibility: Allows tight tolerances without warping during machining
This unique combination of cast form and stress-relieved temper makes MIC 6 ideal for precision tooling, molds, jigs, and high-stability fixtures, where uniform mechanical and thermal behavior is critical.
Fabrication and Machining of MIC 6 Aluminum
Machinability
MIC 6 aluminum exhibits excellent machinability, making it ideal for:
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CNC milling and turning
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Drilling and boring
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Precision tooling and fixture components
Its uniform microstructure and low residual stress allow for machining with minimal warping, reducing the need for post-machining flattening or stress relief.
Welding
Welding MIC 6 is generally not recommended, as it can compromise:
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Flatness and dimensional stability
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Mechanical consistency of the plate
Mechanical fastening or adhesive bonding is preferred for assemblies requiring structural integrity.
Surface Finishing
MIC 6 aluminum is compatible with multiple finishing methods, including:
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Anodizing: Improves surface hardness and corrosion resistance
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Sandblasting: Creates uniform texture for coatings
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Painting or powder coating: Enhances corrosion protection and aesthetic appearance
These finishing options make MIC 6 suitable for precision tooling, molds, and high-stability fixtures in industrial applications.
Applications of MIC 6 Aluminum
MIC 6 aluminum is widely used in industries that require high dimensional stability, flatness, and precision machining, including:
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Inspection tools, jigs, and fixture bases: Provides stable reference surfaces for precision measurement
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High-precision workholding and assembly fixtures: Maintains flatness and minimizes distortion during machining
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Vacuum chambers and precision instrument bases: Excellent stability under thermal and mechanical loads
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Semiconductor equipment substrates: Supports critical processes requiring low thermal expansion
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3D printer platforms and automation equipment frames: Offers rigidity and flatness for consistent performance
Its combination of excellent flatness, uniform mechanical properties, and machinability makes MIC 6 a preferred material for applications where precision and stability are critical.
Surface Finishing and Corrosion Resistance of MIC 6 Aluminum
MIC 6 aluminum exhibits moderate natural corrosion resistance, typical of most aluminum alloys. However, its corrosion resistance can be significantly enhanced through surface treatments, making it suitable for precision tooling and industrial applications where longevity and durability are important.
Comparison with 6061 Aluminum:
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6061 aluminum generally has slightly better intrinsic corrosion resistance due to its magnesium-silicon alloy composition.
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MIC 6 prioritizes dimensional stability and flatness over corrosion resistance, so protective surface treatments are often applied.
Recommended Surface Treatments:
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Anodizing: Improves corrosion resistance and surface hardness while allowing for coloring
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Chemical conversion coatings (e.g., chromate or non-chromate treatments): Provides additional protection against oxidation
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Powder coating or paint finishes: Adds both corrosion resistance and aesthetic appeal
These treatments help maintain MIC 6’s precision, stability, and appearance, even in moderately corrosive environments.
Standards and Specifications of MIC 6 Aluminum
MIC 6 aluminum is primarily produced according to Alcoa proprietary standards, ensuring consistent flatness, dimensional stability, and mechanical properties for precision applications.
Key Standards:
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ASTM B209: Standard specification for aluminum and aluminum-alloy sheet and plate (applicable for MIC 6 plate forms)
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Alcoa MIC 6 Standard: Defines tolerances, flatness, stress-relief treatments, and dimensional stability
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International Equivalents: While MIC 6 is proprietary, specifications can be cross-referenced with general aluminum plate standards for engineering purposes
Customization Options:
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Thickness ranges as required by design or application
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Tighter dimensional tolerances and flatness for precision tooling
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Surface finish and pre-machining treatment according to customer requirements
These standards ensure MIC 6 aluminum is suitable for high-precision tooling, jigs, fixtures, and industrial applications requiring exceptional stability.
Advantages and Limitations of MIC 6 Aluminum
Advantages
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Exceptional Flatness and Dimensional Stability: Minimal warping or distortion during machining.
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Stress-Relieved Structure: Reduced internal stresses decrease the risk of post-machining deformation.
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Excellent Damping Properties: Absorbs vibrations effectively, ideal for precision tooling and measuring equipment.
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High Precision Applications: Well-suited for jigs, fixtures, molds, and instrument bases where stability is critical.
Limitations
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Lower Strength Compared to 6XXX/7XXX Series: Not intended for high-load structural components.
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Welding Not Recommended: Welding can compromise flatness and stability.
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Limited Structural Load Applications: Best used for precision tooling rather than heavy-duty structural parts.
Related Alloys and Alternatives
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6061 Aluminum: Suitable for general structural applications, offering higher tensile strength than MIC 6 but lower flatness and dimensional stability.
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7075 Aluminum: High-strength alloy ideal for aerospace applications; however, it does not match MIC 6 in flatness or stability for precision tooling.
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Cast Aluminum Tooling Plate Alternatives: Other stress-relieved casting alloys such as ATP-5 and ALCA 5 provide similar flatness and stability characteristics, making them viable alternatives for high-precision fixtures, molds, and tooling applications.
Conclusion
MIC 6 aluminum plate stands out for its exceptional flatness, dimensional stability, and excellent machinability. Unlike 6061 or 7075 aluminum, which prioritize strength, MIC 6 is optimized for precision tooling, molds, and fixtures rather than high-load structural applications. Its unique combination of stability and workability makes it an essential material in precision manufacturing, jigs and fixtures, semiconductor equipment, and other high-accuracy industrial applications.
FAQs
What is MIC 6 aluminum?
MIC 6 aluminum is a precision cast aluminum tooling plate developed by Alcoa, designed for applications requiring high flatness, dimensional stability, and uniform mechanical properties.
What are MIC 6 aluminum properties?
MIC 6 offers excellent flatness, low residual stress, good vibration damping, and consistent mechanical performance, making it ideal for precision machining and tooling applications.
What is the chemical composition of MIC 6 aluminum?
Typical composition includes aluminum as the balance, with small amounts of silicon (0.4–0.7%), iron (0.3%), copper (0.25%), manganese (0.1%), magnesium (0.1%), zinc (0.1%), and titanium (0.06%).
What is MIC 6 aluminum density?
The density of MIC 6 aluminum is approximately 2.70 g/cm³.
How does MIC 6 aluminum compare to 6061 aluminum?
Compared to 6061, MIC 6 has lower tensile strength but significantly superior flatness and dimensional stability, making it more suitable for precision tooling rather than structural components.
Can MIC 6 aluminum be welded?
Welding is generally not recommended, as it can compromise flatness and dimensional stability. Mechanical fastening or bolting is preferred for assembly.
What are typical applications of MIC 6 aluminum plate?
MIC 6 is commonly used for precision jigs and fixtures, molds, high-accuracy workbenches, semiconductor equipment bases, vacuum chambers, and 3D printer platforms.
About the Author: Gavin Xia
This article was written by engineers from the RAPID PROTOS team. Gavin Xia is a professional engineer and technical expert with 20 years of experience in rapid prototyping, metal parts, and plastic parts manufacturing.
