Guides / Design

Aluminum Alloys for 5-Axis Prototypes: 6061, 7075 and 2024

October 23, 2026

Aluminum is the default material for 5-axis prototypes. It cuts fast, holds tolerance, costs little compared with titanium or stainless and is available in every shop. Yet “aluminum” on a drawing covers dozens of alloys with different strength, corrosion behavior and price. Three of them account for most prototype orders: 6061, 7075 and 2024.

This guide compares them on the points that matter for a prototype and gives a simple way to choose. If you are weighing material against cost, see what a 5-axis prototype costs and the materials table on the home page.

The three alloys at a glance

Property	6061-T6	7075-T6	2024-T3 or T351
Alloy family	Mg and Si	Zn, Mg and Cu	Cu and Mg
Typical tensile strength	About 310 MPa	About 570 MPa	About 470 MPa
Typical yield strength	About 275 MPa	About 500 MPa	About 325 MPa
Density	About 2.70 g/cm3	About 2.81 g/cm3	About 2.78 g/cm3
Corrosion resistance	Good	Fair, sensitive in some tempers	Fair to poor, often coated
Fusion welding	Yes	No	No
Anodizing	Even, predictable	Works, color can vary	Works, needs attention
Machinability	Good, can be gummy	Very good, clean chips	Very good
Relative stock price	Baseline	About 1.3 to 2 times	About 1.3 to 2 times

All strength numbers are typical handbook values for the stated temper, and they vary by product form and thickness. Check the mill certificate for the batch you buy.

6061: the default

6061-T6 is the general-purpose choice. It is strong enough for brackets, housings, fixtures and enclosures, resists corrosion well, welds and anodizes cleanly in clear and in color. It is stocked in bar, plate and extrusion in almost every size.

On the machine, 6061 is easy to cut but can be gummy: the chips stick and stringy swarf wraps around the tool. Shops control this with sharp, polished tools, high speeds and good coolant. A prototype in 6061 usually costs the least of the three, with the shortest lead time.

Good for: form and fit models, enclosures, general brackets, anything that will be welded or anodized in color and early test builds.

7075: when strength decides

7075-T6 is much stronger and stiffer in practice than 6061. It is the alloy behind many aerospace fittings, high-load brackets, camera and drone parts and sporting goods. It machines very cleanly with short chips, and it holds a sharp edge and fine detail well.

The trade-offs:

• Cost. Stock costs more and shops often have less on the shelf.
• Corrosion. 7075-T6 is more sensitive to corrosion and to stress corrosion cracking in some conditions. Over-aged tempers such as T73 improve this at some loss in strength.
• No fusion welding. Welding degrades the alloy and usually cracks it.
• Anodizing color. Color can be uneven, and dark dyes can show variation between lots.

Good for: stressed brackets, tooling, fixtures, drone and robotic parts, anything where weight and stiffness count.

2024: for fatigue and damage tolerance

2024 is a copper alloy used in aircraft skins and structure for its fatigue behavior. It machines well and has good strength, but it corrodes more readily than 6061, and the usual practice is to coat it, anodize it or buy it clad. It does not weld by normal fusion methods.

On a prototype, you pick 2024 mainly because the final design calls for it. If the production part will be 2024, a prototype in 2024 gives the closest behavior in test, finish and machining. If not, 6061 or 7075 is usually the better choice.

Good for: parts that will be made in 2024 in production, structural fittings where fatigue matters.

Picking an alloy

Use this order of questions:

1. Will the part carry real load? If no, use 6061. If yes, check whether 6061 meets the stress with margin. If it does not, use 7075.
2. Will the part be welded? If yes, use 6061.
3. What will production use? If the production alloy is known, prototype in it for any strength, fatigue or finish test.
4. What finish is planned? For color anodizing, 6061 is the safer start. For hard anodizing, any of the three works, with differences in thickness and look.
5. How soon do you need it? 6061 is on the shelf at most shops. 7075 and 2024 may add days.

Temper and product form

The temper tells you the heat treatment: T6 is solution treated and artificially aged, T651 and T6511 add stress relief by stretching, T73 is overaged for corrosion resistance and T3 and T351 are common for 2024. Stress relief matters for 5-axis parts, because a block cut on several faces can twist when internal stress is released. Plate sold as T651 and bar as T6511 is more stable. Ask the shop what it uses.

Cast tooling plate, often sold under trade names like MIC-6, is stress-relieved and flat. Shops use it for fixtures and plates that must hold flatness, and it costs more than rolled plate. It is not a drop-in for 6061 in strength-critical parts.

Finish and appearance

Finish	6061	7075	2024
As machined	Good appearance	Very clean surface	Good appearance
Bead blast	Even matte	Even matte	Even matte
Clear anodize	Even	Works	Needs care
Color anodize	Even, many colors	Can vary	Can vary
Hard anodize	Common	Common	Common, check with the finisher
Chem film	Common	Common	Common

Tell the shop and the finisher the alloy and the temper. Finishing costs often add a minimum lot charge, so group parts when you can.

What the alloy does to the quote

Aluminum alloys all cut fast, so machine time differences are small. Price differences come from stock cost and availability. As rough orientation, the stock for a small part is a minor part of the quote in 6061 and a bit larger in 7075. The bigger effect is on the schedule if the shop has to order bar or plate.

Checklist before you send the RFQ

1. Alloy and temper written out, for example 6061-T6 or 7075-T651.
2. Whether the part will be welded.
3. Finish and color if any, including hard anodize if needed.
4. Mill certificate requirement.
5. Production alloy, if different from the prototype.
6. Tolerance on features likely to move after stress release.

Send the part through the RFQ page. We match it with up to three 5-axis shops, and you get a reply within 24 business hours.

Frequently asked questions

Keep reading

• Fixturing a 5-Axis Prototype: Dovetails, Pull Studs and Soft Jaws
• 5-Axis Prototype Tolerances and Inspection: What to Specify and What to Ask For