For most custom aluminum parts, the common choices are 5052, 6061, 6063, 6082, and 7075. However, each aluminum alloy behaves differently during extrusion, CNC machining, bending, welding, anodizing, and long-term use.
If you are choosing aluminum for a custom profile, enclosure, heat sink, machined component, frame, bracket, or industrial part, this guide will help you understand the differences between aluminum alloy series and make a more practical material decision.
How Aluminum Alloy Numbers Work
Most wrought aluminum alloys use a four-digit numbering system. The first digit shows the main alloying element.
| Series | Main Alloying Element | General Character |
|---|---|---|
| 1xxx | Pure aluminum | High conductivity, low strength |
| 2xxx | Copper | High strength, lower corrosion resistance |
| 3xxx | Manganese | Good formability and corrosion resistance |
| 4xxx | Silicon | Lower melting point, good for welding and brazing |
| 5xxx | Magnesium | Good strength, weldability, and corrosion resistance |
| 6xxx | Magnesium + silicon | Good strength, machinability, extrusion, and anodizing |
| 7xxx | Zinc | Very high strength, lower weldability |
| 8xxx | Other elements | Special applications such as foil and packaging |
The first digit helps you understand the alloy family. The full grade, such as 5052, 6061, or 7075, gives a more specific material identity. The temper, such as T5, T6, H32, or O, also has a major effect on strength, forming behavior, and machining performance.
Aluminum Alloy Series Overview
Currently, there are seven aluminum alloy series used in the aluminum fabrication industry. Understanding the properties of common alloys helps you choose the right material for your product more quickly.
1xxx Series Aluminum Alloys
The 1xxx series contains at least 99% aluminum. Because of its high purity, it has excellent electrical conductivity, thermal conductivity, corrosion resistance, and ductility.
However, 1xxx aluminum has low mechanical strength. It is not usually selected for structural parts or load-bearing components.
2xxx Series Aluminum Alloys
The 2xxx series uses copper as the main alloying element. These alloys provide high strength and good fatigue resistance, making them suitable for aerospace and high-stress structural applications.
The main disadvantage of this aluminum alloy serie is corrosion resistance. Because of the copper content, 2xxx alloys usually need protective surface treatment, cladding, coating, or controlled service conditions.
Choose 2xxx series when high strength and fatigue resistance are more important than corrosion resistance and weldability.
3xxx Series Aluminum Alloys
The 3xxx series uses manganese as the main alloying element. These alloys usually provide moderate strength, excellent formability, good corrosion resistance, and good workability.
They are widely used in sheet metal products, cookware, chemical equipment, storage tanks, and heat exchangers.
4xxx Series Aluminum Alloys
The 4xxx series uses silicon as the main alloying element. Silicon lowers the melting point and improves fluidity when molten. This makes 4xxx alloys common in welding wire, brazing filler, and some automotive applications.
5xxx Series Aluminum Alloys
The 5xxx series uses magnesium as the main alloying element. These alloys provide good strength, excellent corrosion resistance, and good weldability. They perform especially well in marine, humid, and outdoor environments.
5xxx alloys are commonly used for sheet metal, tanks, marine parts, pressure vessels, vehicle panels, and formed components.
5052 and 5083 are often used to manufacture marine components. They offer excellent resistance to seawater corrosion.
6xxx Series Aluminum Alloys
The 6xxx series uses magnesium and silicon as the main alloying elements. These elements form Mg2Si, which allows the alloy to be strengthened by heat treatment.
This series is very important in custom aluminum manufacturing because it offers a strong balance of strength, extrudability, corrosion resistance, weldability, machinability, and surface finish.
Choose 6xxx series for most custom extruded aluminum profiles, CNC machined aluminum parts, enclosures, heat sinks, frames, and general industrial components.
7xxx Series Aluminum Alloys
The 7xxx series uses zinc as the main alloying element, often with magnesium and copper. These alloys provide very high strength and excellent strength-to-weight ratio.
7075 is the most recognized grade in this series. It is used in aerospace, defense, high-performance sports equipment, molds, and precision parts that require high stiffness and strength.
7075 machines well, but it has lower corrosion resistance and poor weldability compared with 6061 and 6063. It is also more expensive. If the part only requires general strength, 6061 may be more cost-effective.
Common Aluminum Grades for Custom Manufacturing
For custom aluminum products, engineers and purchasing teams usually do not compare all alloy series. They often compare a smaller group of practical grades.
| Alloy | Best For | Main Advantages | Limitations |
|---|---|---|---|
| 3003 | Formed sheet parts | Good formability, corrosion resistance, low cost | Lower strength |
| 5052 | Sheet metal enclosures, bent parts, marine parts | Good corrosion resistance and bending performance | Not ideal for complex extrusion |
| 6061 | CNC machining, frames, brackets, structural parts | Balanced strength, machinability, weldability, anodizing | More difficult to bend in T6 temper |
| 6063 | Extruded profiles, decorative parts, enclosures | Excellent extrudability and surface finish | Lower strength than 6061 and 6082 |
| 6082 | Structural extrusions and load-bearing parts | Higher strength, good machining performance | Higher cost and processing difficulty |
| 7075 | High-strength machined parts | Very high strength and stiffness | Poor weldability, lower corrosion resistance, higher cost |
For most custom aluminum extrusions, 6063 is suitable when surface quality and profile complexity are important. 6061 is better when the part needs more strength and secondary CNC machining. For more information on these two materials, please refer to our guide on 6061 vs 6063.
6082 is suitable for stronger structural profiles. 7075 is usually selected only when high strength is required and the profile design is not too complex.
Common Mistakes When Choosing Aluminum Alloys
Only Looking at Strength
A stronger alloy is not always better. 7075 has very high strength, but it costs more, has lower corrosion resistance, and is not ideal for welding. For many industrial parts, 6061 provides a better balance.
Choosing 6063 for Heavy Load Structures
6063 is excellent for extrusion and surface appearance, but it has lower strength than 6061 and 6082. For load-bearing parts, confirm the mechanical requirements before choosing 6063.
One of our customers previously experienced material cracking because 6063 aluminum was used for the part. We recommended switching to 6061-T6, and the actual result was very good, with no strength-related issues reported.
Ignoring Surface Finish Requirements
The same alloy can look different after anodizing, brushing, sandblasting, or powder coating. If color consistency and appearance are important, material selection and surface preparation should be discussed early.
CNC drilling and Tapping After Extrusion
If the extruded profile requires extensive drilling, tapping, milling, and assembly, 6063 may cause weaker threads and more burrs.
For mounting plates, connection components, brackets, and screw-fastened structures, 6061-T6 is usually more suitable.
Practical Recommendations from Custom Aluminum Manufacturing
For custom aluminum enclosures, 6063 is often suitable for extruded housings that need a good appearance, anodizing, and clean profile design. If the enclosure needs many CNC-machined openings, threaded holes, mounting features, or stronger structure, 6061 may be more suitable.
For heat sinks, 6063 is commonly used because it extrudes well and provides good thermal performance for many profile designs. For machined heat sink blocks or structural cooling components, 6061 can also be used.
For CNC machined brackets, plates, frames, and precision parts, 6061 is usually the most practical material because it offers stable machining, good strength, and good surface treatment options.
For sheet metal covers, panels, and bent parts, 5052 is often a better choice than 6061-T6 because it forms more easily and has good corrosion resistance.
For high-strength lightweight parts, 7075 can be considered, but the project should accept higher cost, limited weldability, and additional corrosion protection requirements.
Conclusion
Different aluminum alloy series are designed for different performance requirements.
For most custom aluminum product projects, material selection should not stop at the alloy name. You should also consider extrusion difficulty, CNC machining performance, bending behavior, welding, surface treatment, cost, and the final working environment.
If you have a drawing, sample, or custom aluminum product idea, Zheng Ji Aluminum can help review the material, manufacturing process, surface treatment, and production feasibility before mass production.
