Aluminum is the most-machined metal in CNC for good reason: a strong strength-to-weight ratio, excellent machinability, natural corrosion resistance, and easy anodizing. But “aluminum” is not one material. The grade decides strength, corrosion resistance, machinability, and cost, and picking the wrong one means a part that is over-built, too weak, or needlessly expensive. The short version: 6061 is the versatile workhorse, 6063 is the finish-and-extrusion grade, 5052 and 5083 are the marine corrosion grades, and 7075 is the aerospace-strength grade.
This guide compares the five grades engineers ask for most, so you can specify with confidence. For the full catalog, see our materials range, and pair this with our guides to steel grades and stainless steel grades.
A Quick Word on the Series
The first digit of an aluminum grade tells you its main alloying element. The 6xxx series (magnesium and silicon) is the all-round workhorse, heat-treatable and easy to machine. The 7xxx series (zinc) is the high-strength option. The 5xxx series (magnesium) is the corrosion and marine family, very weldable but not heat-treatable. That framing alone narrows most choices.
The Five Grades
6061 — The Workhorse
6061 is the default for most CNC work. It offers a strong balance of mechanical properties, excellent machinability, good weldability and corrosion resistance, heat-treatability (commonly supplied as 6061-T6), and it anodizes well. It machines fast with low tool wear, which keeps cycle times and cost down. Use it for structural parts, brackets, housings, and general components. See our 6061 aluminum bar.
6063 — The Finish and Extrusion Grade
6063 shares 6xxx chemistry but trades some strength for a superior surface finish and excellent extrudability, which is why it dominates architectural profiles like window and door frames. It anodizes beautifully and resists corrosion well, making it the pick when appearance matters more than maximum strength. See our 6063 aluminum plate.
5052 — The Corrosion-Resistant Sheet Grade
5052 offers excellent corrosion resistance, especially in marine environments, plus high fatigue strength and very good formability and weldability. It is not heat-treatable, and its tensile and shear strength sit below 6061 and 7075. It is a sheet-metal favorite for enclosures, tanks, and marine parts. See our 5052 aluminum plate.
5083 — The Marine and Extreme-Environment Grade
5083 is the strongest of the common non-heat-treatable alloys and performs superbly in harsh and marine settings, which is why it is specified for shipbuilding and offshore work. It is highly weldable and keeps its strength in extreme conditions. See our 5083 aluminum plate.
7075 — The Aerospace-Strength Grade
With zinc as its primary alloying element, 7075 reaches strength comparable to some steels and has the highest shear strength of this group, earning its “aircraft grade” name. It is heat-treatable (7075-T6). The trade-offs: it is harder and slower to machine with more tool wear, costs more, is not readily weldable, and has lower corrosion resistance than the 5xxx and 6xxx grades. Reserve it for high-stress and aerospace parts. See our 7075-T651 aluminum plate.
Side-by-Side
| Grade | Series | Strength | Machinability | Corrosion / marine | Heat-treatable | Best for |
| 6061 | 6xxx | Good | Excellent | Good | Yes | General workhorse |
| 6063 | 6xxx | Moderate | Good | Good | Yes | Extrusions, finish, anodizing |
| 5052 | 5xxx | Moderate | Good | Excellent | No | Sheet metal, marine |
| 5083 | 5xxx | High (non-HT) | Good | Excellent | No | Shipbuilding, extreme |
| 7075 | 7xxx | Very high | Fair (slower) | Lower | Yes | Aerospace, high stress |
How to Choose
Default to 6061 unless you have a specific reason not to; it covers the large majority of parts at the best balance of cost and machinability. Step up to 7075 only when you genuinely need maximum strength and can accept higher cost and slower machining. Choose 5052 or 5083 when corrosion resistance, especially marine, or weldability is the priority, remembering they are not heat-treatable. Choose 6063 when surface finish, anodized appearance, or extrusion drives the design. For anodized parts, the 6xxx grades finish best, which pairs with our surface finishing options.
Not sure which grade fits? Request a quote and we will recommend the right aluminum and temper.
Frequently Asked Questions
What is the best aluminum grade for CNC machining?
6061 is the best all-around choice for most parts, offering excellent machinability, good strength and corrosion resistance, weldability, and easy anodizing at a reasonable cost. Other grades are chosen for specific needs like maximum strength or marine corrosion resistance.
What is the difference between 6061 and 7075 aluminum?
6061 is versatile, easy to machine, weldable, and economical. 7075 is much stronger, approaching some steels, but is harder and slower to machine, more expensive, not readily weldable, and less corrosion-resistant. Use 7075 only when high strength is essential.
Which aluminum is best for marine or corrosive environments?
5052 and 5083 offer the best corrosion resistance, especially in marine settings. 5083 is the stronger of the two and is used in shipbuilding and offshore applications.
Which aluminum grade anodizes best?
The 6xxx grades, especially 6061 and 6063, anodize very well. 6063 in particular gives an excellent finish, which is why it is favored for architectural and cosmetic parts.