6061-T6 temper
70% of brass
W/mK
lb/in³
What Is Aluminum 6061-T6?
Aluminum 6061-T6 is the most common aluminum alloy used in CNC machining. It is strong, light, and easy to machine. If you are not sure which aluminum to pick, start with 6061-T6. It works for most parts.
The "6061" refers to the alloy. It contains magnesium and silicon, which give it good strength and corrosion resistance. The "T6" refers to the temper. T6 means the metal was heated, quenched, and aged to reach its peak strength — 45 ksi tensile and 40 ksi yield.
Engineers choose 6061-T6 because it does everything well. It machines fast. It anodizes in many colors. It welds with standard equipment. It resists corrosion without any coating. And it costs less than almost every other metal. That is why it is the default choice for CNC machined parts across every industry.
Aluminum 6061-T6 Material Properties
Here are the key properties of 6061-T6 and why each one matters for your parts.
| Property | Value | Why It Matters |
|---|---|---|
| Tensile Strength | 45 ksi (310 MPa) | Strong enough for most structural parts. Brackets, frames, and housings. |
| Yield Strength | 40 ksi (276 MPa) | The point where the metal bends and stays bent. Design below this number. |
| Elongation | 12% | Good ductility. The part bends before it breaks. Safer in crash or impact loads. |
| Hardness | Brinell 95 / Rockwell B60 | Hard enough to resist dents. Soft enough to machine fast with sharp tools. |
| Thermal Conductivity | 167 W/mK | Excellent heat transfer. Great for heat sinks, cold plates, and thermal management. |
| Density | 0.098 lb/in³ (2.70 g/cm³) | About 1/3 the weight of steel. Saves weight in every application. |
| Machinability | Good — 70% of brass | Cuts fast and clean. Low tool wear. Short cycle times keep costs down. |
| Corrosion Resistance | Good | Resists rust in normal environments. Anodizing makes it even better. |
| Weldability | Excellent | TIG or MIG with 4043/5356 filler. Easy to join machined parts by welding. |
| Anodizing | Excellent | Takes color well. Smooth, even finish in clear, black, red, blue, or gold. |
Common 6061 Tempers
The temper changes how strong and hard the aluminum is. Here are the three 6061 tempers you will see most often.
| Temper | Tensile Strength | Yield Strength | Best For |
|---|---|---|---|
| 6061-T6 | 45 ksi | 40 ksi | Most CNC parts. Peak strength. Default choice for brackets, housings, frames. |
| 6061-T651 | 45 ksi | 40 ksi | Same strength as T6, but stress-relieved by stretching. Flatter plate stock. Better for large, thin parts that need to stay flat after machining. |
| 6061-O | 18 ksi | 8 ksi | Fully annealed (soft). Used when you need to bend or form the part before heat treating to T6. Not for structural parts in this condition. |
Which temper should you pick? Use 6061-T6 for almost everything. Use 6061-T651 for large flat parts (over 6 inches) where warping matters. Use 6061-O only if you need to bend the part first and heat treat later.
Aluminum 6061 vs Other Materials
How does 6061-T6 compare to other popular CNC materials? This table shows the key differences.
| Property | 6061-T6 | 7075-T6 | Stainless 304 | Delrin |
|---|---|---|---|---|
| Tensile Strength | 45 ksi | 83 ksi | 75 ksi | 10 ksi |
| Density | 0.098 lb/in³ | 0.102 lb/in³ | 0.289 lb/in³ | 0.051 lb/in³ |
| Machinability | Good (70%) | Fair (60%) | Poor (36%) | Excellent (100%+) |
| Cost per Part | $65–$300 | $85–$400 | $120–$400 | $50–$200 |
| Corrosion Resistance | Good | Fair | Excellent | Excellent |
| Weldable | Yes | No (difficult) | Yes | No |
| Anodizing | Excellent | Good (darker) | N/A | N/A |
| Best For | General purpose | High-stress parts | Corrosive environments | Low-friction parts |
Bottom line: Use 6061-T6 unless you have a specific reason not to. Need 2x more strength? Use 7075-T6. Need corrosion resistance in salt water or chemicals? Use stainless 304 or 316. Need a plastic? Use Delrin or PEEK.
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Upload CAD for Instant QuoteIndustries and Applications
Aluminum 6061-T6 is used in almost every industry. Here are the most common applications we machine.
Aerospace
Brackets, fittings, structural supports, and avionics housings. 6061-T6 meets AMS 4027 and AMS-QQ-A-250/11 specs. Lighter than steel at 1/3 the weight.
Medical Devices
Instrument housings, surgical tool handles, fixture plates, and device enclosures. Anodized 6061-T6 is easy to clean and sterilize. Non-magnetic.
Robotics & Automation
Motor mounts, end effectors, sensor brackets, and chassis plates. Light weight keeps payload high. Easy to iterate — new designs ship in days.
Consumer Electronics
Enclosures, heat sinks, bezels, and structural frames. Anodized in black, silver, or custom colors. 167 W/mK thermal conductivity pulls heat away from chips.
Semiconductor
Wafer handling components, cold plates, and chamber fittings. Tight flatness on large plates. Chemical compatibility with most cleaning solvents.
Hardware Startups
Prototype housings, structural brackets, and first-run production parts. Low cost lets you test 3 designs for the price of 1 in stainless steel.
Design Tips for Machining Aluminum 6061
Aluminum 6061 is easy to machine, but smart design choices save you time and money. Follow these tips for the best results.
- Add inside corner radii of 0.030" or larger. End mills are round. Sharp inside corners need a slow EDM pass that costs 3–5x more. A 0.030" radius costs nothing extra.
- Keep walls at 0.040" thick or more. Thin walls flex during cutting. This causes chatter marks and slows the machine. Walls at 0.060"+ machine fastest.
- Limit pocket depth to 4x width. A pocket 5x deeper than it is wide needs a long, thin tool that chatters. Stay under 4:1 for clean finishes.
- Use standard drill sizes. Sizes like 1/8", 3/16", 1/4" cost less than non-standard holes. Standard taps (4-40, 6-32, 8-32, 10-32, 1/4-20) are also cheaper.
- Only tighten tolerances where they matter. Use ±0.005" for general features. Save ±0.001" for fits and mating surfaces. This cuts inspection time.
- Avoid deep, narrow slots. A slot 0.040" wide and 0.500" deep needs a tiny tool that breaks easily. Make slots at least 1/4 as wide as they are deep.
- Design flat bottoms when possible. Flat-bottom pockets machine faster than radiused or contoured bottoms. Save 3D surfacing for where it matters.
Surface Finishes for Aluminum 6061
6061 takes finishes better than almost any metal. Here are the finishes we offer.
- As-machined (125 Ra): Clean tool marks visible. Ready to use for internal parts, fixtures, and prototypes. No extra cost.
- Bead blasted: Uniform matte texture. Hides tool marks. Popular for housings and enclosures. Adds 1–2 days.
- Type II anodizing: Hard oxide layer in clear, black, red, blue, or gold. Adds corrosion resistance and a professional look. Layer is 0.0002–0.001 inches thick.
- Type III hard anodizing: Thicker oxide layer (0.001–0.002 inches). Very hard at 60–70 Rockwell C. For high-wear parts like pistons, slides, and gears.
- Powder coat: Durable paint finish in any RAL color. Great for outdoor parts. Thicker than anodizing at 0.002–0.006 inches.
- Chromate conversion (Alodine): Thin chemical coating per MIL-DTL-5541. Gold or clear. Adds corrosion resistance while keeping electrical conductivity. Common in aerospace.
- Nickel plating: Adds a bright, hard surface to aluminum. Electroless nickel gives uniform coverage even in holes and pockets.
- Tumble/deburr: Removes sharp edges. Safe to handle. Standard on all parts unless noted otherwise.
Tolerances for Aluminum 6061 CNC Parts
Aluminum 6061 holds tight tolerances well because it does not work-harden during cutting. Here is what we hold.
| Tolerance Level | Value | Use Case |
|---|---|---|
| Standard | ±0.005" (±0.127 mm) | General features, non-critical dimensions, clearance holes. |
| Precision | ±0.001" (±0.025 mm) | Bearing fits, mating surfaces, alignment pins, dowel holes. |
| Critical | ±0.0005" (±0.013 mm) | Optical mounts, sealing surfaces, high-precision assemblies. Requires CMM inspection. |
Surface finish tolerances: As-machined is 125 Ra or better. We can hold 32 Ra or 16 Ra on request. Ground surfaces hold flatness of 0.001" per inch.
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