6061-T6 Aluminum — CNC Machining Specs

// Material Science

6061-T6 Mechanical Properties

Data per ASTM B209 / AMS 2770. T6 temper achieved by solution heat treatment at 980°F followed by artificial aging at 320°F. Properties not guaranteed — reference only.

Tensile Strength (UTS)

45

ksi (310 MPa)

Yield Strength (0.2%)

40

ksi (276 MPa)

Elongation at Break

12%

in 2 inches

Brinell Hardness

95

HB (Brinell)

Density

2.70

g/cm³ (0.098 lb/in³)

Elastic Modulus

10,000

ksi (68.9 GPa)

Thermal Conductivity

96

BTU/hr·ft·°F

Melting Point

1,202

°F (650 °C)

Why T6 temper? The "T6" designation means the alloy was solution heat-treated (heated to dissolve alloying elements) then artificially aged (reheated at lower temp). This Mg₂Si precipitation hardening process more than doubles the yield strength compared to annealed 6061.

Anodizing advantage. Unlike most high-strength alloys, 6061-T6 anodizes exceptionally well. Copper content is kept below 0.4% specifically to preserve anodize quality — making it ideal for Type II clear, color, and Type III hardcoat finishes.

// CNC Envelope

Max Machining Area

Our CNC machining centers accommodate 6061-T6 parts up to the envelope shown below. Tolerances default to ISO 2768-1 medium (m) class — fine (f) class available on request.

// Maximum Part Envelope

500 × 500 × 300

mm

19.7 × 19.7 × 11.8 inches · X × Y × Z axes

X Axis

500 mm

19.7 in

Y Axis

500 mm

19.7 in

Z Axis (Depth)

300 mm

11.8 in

ISO 2768-1

Fine Class (f)

→

Tight tolerances for precision-fit features, bearing bores, and mating surfaces. Available on request — quote may reflect additional setup time.

Linear (0.5–6mm)

±0.05 mm

Linear (>6–30mm)

±0.10 mm

Linear (>30–120mm)

±0.15 mm

Angular

±0°5' (5 arcmin)

Click for full tolerance table →

DEFAULT

ISO 2768-1

Medium Class (m)

→

Standard workshop tolerance for general machined features, enclosures, brackets, and structural components. Applied by default unless otherwise specified.

Linear (0.5–6mm)

±0.10 mm

Linear (>6–30mm)

±0.20 mm

Linear (>30–120mm)

±0.30 mm

Angular

±0°10' (10 arcmin)

Click for full tolerance table →

How to specify tolerance on your drawing. Add a general tolerance block to your title page: GENERAL TOLERANCE: ISO 2768-1 f or ISO 2768-1 m. Individual features with tighter requirements should be called out directly on the feature with their own tolerance block or GD&T frame.

// CNC Performance

Machinability & Cutting Data

6061-T6 is one of the most machinable aluminum alloys available. Rated at 95% machinability (versus 100% for free-cutting B1112 steel reference). Produces excellent surface finishes with standard HSS and carbide tooling.

Machinability Rating	95% (Excellent)
Chip Character	Short to medium chips
Recommended Tool Material	Carbide / HSS
Cutting Speed (HSS)	500–1,000 SFM
Cutting Speed (Carbide)	1,000–3,000 SFM
Drill Feed Rate	0.004–0.012 IPR
Coolant / Lubricant	Flood coolant or MQL
Min Wall Thickness (milled)	0.040″ rec. / 0.020″ abs.
Min Hole Diameter	0.020″ (drilled)
Thread Engagement	1.5× diameter rec.

Machinability95/100

Surface Finish Quality90/100

Thread Holding Ability80/100

Anodize Suitability95/100

Corrosion Resistance75/100

Weldability70/100

⚠️

Post-Weld Heat Treatment Required

Welding 6061-T6 reduces strength in the heat-affected zone (HAZ) to levels similar to annealed 6061 (~18 ksi yield). If structural strength must be maintained, the welded assembly should be re-solution-treated and aged (re-T6'd) after welding. For lightly-loaded joints, ER4043 or ER5356 filler wire without re-treatment is common practice.

// Fabrication Services

Available for 6061-T6

All Xeon NC CNC machining services are fully compatible with 6061-T6 Aluminum.

⚙

3-Axis CNC Milling

Pockets, slots, contours, and face milling. Tolerances to ±0.001″.

○

CNC Turning / Lathe

Turned round bar stock. OD/ID features, knurling, grooves, and threads.

◎

Tapping & Threading

Blind and through holes. UN, UNF, and metric thread forms available.

⊙

Countersinking

82° and 100° countersinks for flush fastener seating.

▣

Hardware Insertion

Heat-set inserts and press-fit threaded inserts for plastic-to-metal assemblies.

◆

Deburring & Edge Break

All machined parts are deburred and edge-broken by default.

✦

Type II Anodizing

Clear or color anodize. Creates a UV-resistant, corrosion-proof oxide layer integral to the surface.

🎨

Powder Coating

10+ RAL colors. Applied over bare or anodized aluminum. Typically +0.003″ per side.

// Common Questions

6061-T6 FAQ

Engineering and ordering questions answered.

What's the difference between 6061-T6 and 6061-T651?

+

T651 is T6 plus stress-relieved by stretching after artificial aging. This eliminates residual stresses introduced during heat treatment. For CNC machining plate, T651 is preferred because it machines flatter with less springback and distortion — especially important for precision fixtures and thick sections. Xeon NC stocks T651 plate where noted in the stock table.

Can I anodize 6061-T6 after machining?

+

Yes — 6061-T6 anodizes excellently. Type II (standard, 0.0002″ depth) and Type III hardcoat (0.001–0.002″ depth) are both fully compatible. Note that anodizing adds approximately 0.0001–0.0002″ per surface for Type II, so design critical bores and ODs with coating allowance built in. Anodize occurs after all machining operations.

What tolerances can you hold on 6061-T6?

+

Standard tolerance is ±0.005″ on all features. For precision work, we can hold ±0.001″ on milled features and ±0.0005″ on turned ODs/IDs with appropriate toolpath strategies. GD&T callouts for flatness, perpendicularity, and true position are all achievable — please include a tolerance table in your drawing.

Is 6061-T6 suitable for outdoor enclosures?

+

Bare 6061-T6 forms a natural oxide layer that provides moderate outdoor corrosion resistance — better than carbon steel, but not as good as 5052 or 316 stainless. For outdoor applications, we strongly recommend Type II anodize at minimum, or powder coating over anodize for maximum UV and moisture resistance.

What file formats do you accept for CNC machining?

+

We accept STEP (.stp / .step), IGES (.igs), Parasolid (.x_t / .x_b), DXF (.dxf) for 2D profiles, and native SolidWorks (.sldprt). PDF drawings with dimensions are required alongside CAD files for any tolerance-critical or GD&T work. Please include material callout and surface finish callout on your drawing.