CNC Machining Aluminum Services
Precision CNC machining for aluminum parts at FIRMFG. We machine 6061, 7075, 2024, 5052, 6063, and MIC-6 cast plate on 100+ CNC machines including 3-axis, 4-axis, and 5-axis centers. ISO 9001 certified with tolerances to ±0.005 in and surface finishes down to Ra 0.4 μm. Get a quote in 24 hours.
CNC Machining Aluminum: Precision Parts, Alloys & Tolerances
CNC machining aluminum is the cornerstone of modern precision manufacturing. Aluminum is the most widely CNC-machined metal in the world, prized for its exceptional strength-to-weight ratio, superior machinability, natural corrosion resistance, and thermal conductivity. At FIRMFG, we specialize in producing high-precision aluminum CNC machined partsfor aerospace, automotive, electronics, medical, and robotics industries.
Our facility houses over 100 CNC machines, including 3-axis, 4-axis, and full simultaneous 5-axis machining centers, as well as live-tool CNC lathes. We machine every major aluminum alloy — from the general-purpose 6061-T6 to the aerospace-grade 7075-T6 and the dimensionally stable MIC-6 cast tooling plate. Every part is backed by our ISO 9001:2015 certified quality management system and inspected with CMM equipment to verify tolerances as tight as ±0.0005" (±0.013 mm).
Whether you need a single aluminum prototype machined in 3 days or a production run of 1,000 units, FIRMFG delivers consistent quality, competitive pricing, and engineering support at every stage. Our engineers review every CAD file for manufacturability, recommend the optimal alloy and process, and provide free DFM feedback before machining begins.
This guide covers everything you need to know about CNC machining aluminum — alloy selection, mechanical properties, machining processes, speeds and feeds, design rules, surface finishes, and cost optimization. Use it as a reference when designing your next aluminum part, or skip ahead and request a quote for an immediate price and lead time.
Quick Specs: Aluminum CNC Machining
Key mechanical properties of the aluminum alloys we machine, plus FIRMFG's CNC machining capabilities for aluminum parts.
Aluminum Alloy Mechanical Properties
| Alloy | Tensile Strength | Yield Strength | Elongation | Hardness | Machinability |
|---|---|---|---|---|---|
| 6061-T6 | 45 ksi (310 MPa) | 40 ksi (276 MPa) | 17% | 95 HB | Excellent |
| 7075-T6 | 83 ksi (572 MPa) | 73 ksi (503 MPa) | 11% | 150 HB | Good |
| 2024-T3 | 70 ksi (483 MPa) | 50 ksi (345 MPa) | 18% | 120 HB | Good |
| 5052-H32 | 33 ksi (228 MPa) | 28 ksi (193 MPa) | 12% | 60 HB | Fair |
| 6063-T6 | 35 ksi (241 MPa) | 31 ksi (214 MPa) | 12% | 73 HB | Excellent |
| MIC-6 | 24 ksi (165 MPa) | 14 ksi (97 MPa) | 3% | 65 HB | Excellent |
FIRMFG Aluminum Machining Capabilities
| Capability | Specification |
|---|---|
| Standard Tolerance | ±0.005" (±0.13 mm) |
| Precision Tolerance | ±0.002" (±0.05 mm) |
| Max Part Size | 1200 × 600 × 500 mm |
| Surface Finish (As-Machined) | Ra 0.4 – 0.8 μm |
| Machining Axes | 3-Axis / 4-Axis / 5-Axis |
| Quality Standard | ISO 9001:2015 Certified |
Why Aluminum Is the Most CNC-Machined Metal
Aluminum accounts for more CNC machined parts than any other metal. Its unique combination of physical and mechanical properties makes it the default choice for precision manufacturing.
Low Density
At 2.70 g/cm³, aluminum is one-third the weight of steel (7.85 g/cm³). This delivers exceptional strength-to-weight ratios for aerospace and automotive applications where every gram matters.
High Thermal Conductivity
Aluminum conducts heat at 167 W/m·K — roughly four times faster than steel. This makes it ideal for heat sinks, electronic enclosures, and thermal management components.
Excellent Machinability
Aluminum machines at 200% the rate of free-machining steel. Higher cutting speeds mean shorter cycle times, lower tool wear, and significantly reduced per-part cost.
Non-Magnetic & Corrosion-Resistant
Aluminum forms a natural oxide layer that resists corrosion. It is also non-magnetic, making it suitable for sensitive electronic and medical environments.
| Material | Machinability Rating | Cutting Speed Multiplier | Relative Tool Life | Cost Index |
|---|---|---|---|---|
| Aluminum (6061-T6) | 200% | 3 – 5× | 3× | 1.0 |
| Steel (1018) | 100% (baseline) | 1× | 1× | 0.7 |
| Titanium (Grade 2) | 40% | 0.4× | 0.3× | 8.0 |
| Copper (C110) | 20% | 0.3× | 0.2× | 3.0 |
* Machinability rating is relative to AISI 1018 steel (100%). Cutting speed multiplier compares recommended surface feet per minute (SFM) for carbide tooling. Cost index includes both material and machining cost normalized to aluminum 6061.
Sustainability: Aluminum Is 100% Recyclable
Beyond performance, aluminum is one of the most sustainable engineering metals. It is 100% recyclable with no loss of mechanical properties, and remelting aluminum scrap requires only 5% of the energy needed to produce primary aluminum from bauxite ore. FIRMFG recycles all aluminum chips and offcuts from our CNC machining operations, reducing both material cost and environmental impact. For customers targeting LEED certification or reduced carbon footprints, CNC machined aluminum offers an excellent balance of performance and sustainability.
Aluminum Alloys We Machine
FIRMFG machines six primary aluminum alloys, each selected for specific mechanical, thermal, and cosmetic requirements. Below is a detailed guide to help you choose the right alloy for your application.
Aluminum 6061-T6
The General-Purpose Workhorse
Tensile 310 MPa · Excellent weldability · Good corrosion resistance
Typical Applications
Aerospace fittings, automotive frames, bicycle components, electronic enclosures, jigs and fixtures
Best all-around alloy for structural and general-purpose CNC machined parts
Aluminum 7075-T6
Aerospace-Grade Strength
Tensile 572 MPa · Highest strength-to-weight ratio · Lower corrosion resistance
Typical Applications
Aircraft structural members, military equipment, high-stress gears, rock-climbing equipment, drone frames
Best for high-stress applications where maximum strength and weight savings matter
Aluminum 2024-T3
High Fatigue Resistance
Tensile 483 MPa · Excellent fatigue resistance · Fair corrosion resistance
Typical Applications
Aircraft wing tension zones, fuselage structures, high-performance automotive, precision instruments
Best for fatigue-critical aerospace and motorsport components
Aluminum 5052-H32
Marine & Forming Grade
Tensile 228 MPa · Excellent corrosion resistance · High fatigue strength · Good formability
Typical Applications
Marine hardware, fuel tanks, pressure vessels, medical device chassis, electronic shielding
Best for parts exposed to saltwater or requiring exceptional corrosion resistance
Aluminum 6063-T6
Architectural & Extrusion Grade
Tensile 241 MPa · Excellent anodizing response · Good corrosion resistance
Typical Applications
Architectural profiles, heat sinks, LED housings, window frames, decorative trim, electronic enclosures
Best for cosmetic parts requiring a high-quality anodized finish
Aluminum MIC-6
Cast Tooling & Mold Plate
Tensile 165 MPa · Exceptional dimensional stability · Stress-relieved · Flat to 0.005"/ft
Typical Applications
Precision tooling plates, vacuum chucks, molds, jigs, fixtures, base plates, semiconductor equipment
Best for large flat parts requiring tight flatness and dimensional stability
CNC Aluminum Machining Processes
We employ five core CNC machining processes for aluminum, each suited to different part geometries and production requirements. Selecting the right process upfront reduces cost and improves quality.
3-Axis CNC Milling
Standard X/Y/Z milling for prismatic aluminum parts with simple to moderate geometry. The most cost-effective option for prototypes and production brackets, plates, and housings.
Best For
Flat brackets, enclosure plates, simple pockets and slots
4-Axis CNC Machining
Adds a rotary A-axis for indexing, enabling multi-sided machining in a single setup. Reduces re-fixturing errors and improves feature alignment on cylindrical or angled parts.
Best For
Cams, indexing holes, angled features, cylindrical parts with flats
5-Axis CNC Machining
Simultaneous 5-axis machining for the most complex aluminum geometries. Allows the tool to approach any surface at the optimal angle, eliminating multiple setups and improving accuracy.
Best For
Turbine blades, impellers, complex aerospace brackets, medical implants
CNC Turning
Precision lathe operations for cylindrical and rotational aluminum parts. Live-tool turning centers combine milling and turning in one setup for complex turned components.
Best For
Shafts, bushings, pulleys, threaded fittings, custom fasteners
Surface Profiling
Contour milling and profiling of complex 3D surfaces. Combined with high-speed machining strategies, this produces smooth organic shapes ideal for tooling and prototypes.
Best For
Mold cavities, ergonomic handles, organic-form prototypes
Process Selection Guide
| Part Type | Recommended Process | Setups | Notes |
|---|---|---|---|
| Flat plate / bracket | 3-Axis Milling | 1 setup | Most economical |
| Multi-sided prismatic | 4-Axis Machining | 1 setup | Reduces re-fixturing |
| Complex 3D geometry | 5-Axis Machining | 1 setup | Single-setup accuracy |
| Cylindrical / rotational | CNC Turning | 1 setup | OD/ID features |
| Turned + milled features | Live-Tool Turning | 1 setup | Combined operations |
Speeds, Feeds & Tooling for Aluminum
Correct cutting parameters are essential for achieving optimal surface finish, dimensional accuracy, and tool life when CNC machining aluminum.
| Tool Type | SFM (Surface Speed) | IPT (Feed / Tooth) | Recommendation |
|---|---|---|---|
| HSS (High-Speed Steel) | 250 – 400 | 0.003 – 0.008 | Low-volume prototyping, soft alloys, complex form tools |
| Carbide (Uncoated) | 600 – 1,200 | 0.004 – 0.012 | General production, balanced cost and performance |
| Diamond-Coated Carbide | 1,000 – 2,000 | 0.005 – 0.015 | High-volume runs, high-silicon alloys, maximum tool life |
| PCD (Polycrystalline Diamond) | 1,500 – 3,000 | 0.006 – 0.020 | Ultra-high-volume, abrasive aluminum grades, longest tool life |
Preventing Built-Up Edge (BUE)
Aluminum's low melting point (660°C) and high ductility cause material to weld onto the cutting edge, forming a built-up edge. BUE degrades surface finish and pulls material away from the workpiece.
- Use polished, sharp carbide tools with positive rake geometry
- Run at high SFM — higher speeds actually reduce BUE by clearing chips faster
- Apply flood coolant or high-pressure air to evacuate chips and dissipate heat
- Select non-stick coatings: TiB2, diamond, or ZrN outperform TiN or TiAlN for aluminum
Tool Wear Monitoring
Even though aluminum is easy to machine, monitoring tool wear prevents scrap parts and maintains consistent surface finish across production runs.
- Inspect cutting edges every 2-4 hours for aluminum adhesion or flank wear
- Listen for pitch changes in cutting sound — rising pitch signals dull tools
- Monitor spindle load — a 15-20% increase indicates tool deterioration
- Replace tools proactively at 80% of predicted tool life for critical-tolerance parts
Design Rules for CNC Machined Aluminum Parts
Following these design-for-manufacturing (DFM) guidelines reduces machining time, lowers cost, and improves part quality. Minimum values are achievable but increase cost and risk.
| Feature | Recommended | Minimum (Higher Cost) |
|---|---|---|
| Wall Thickness | 0.8 mm (0.031") | 0.5 mm (0.020") |
| Hole Diameter | 1.0 mm (0.040") | 0.5 mm (0.020") |
| Pocket Depth | 4× diameter | 6× diameter |
| Internal Radius | 1.0 mm (0.040") | 0.5 mm (0.020") |
| Thread Size | M2 / #2-56 UNC | M1.6 / #0-80 UNC |
| Edge Fillet / Chamfer | 0.5 mm (0.020") | 0.3 mm (0.012") |
| Floor Thickness | 0.8 mm (0.031") | 0.5 mm (0.020") |
| Engraved Text Width | 0.5 mm (0.020") | 0.3 mm (0.012") |
DFM Tips for Aluminum Parts
- Design internal corners with a radius equal to or larger than the largest available tool diameter to avoid long-reach finishing passes.
- Avoid deep pockets. Keep pocket depth under 4× the tool diameter; deeper pockets require specialized tooling and increase cycle time exponentially.
- Use standard hole sizes (imperial or metric) to allow off-the-shelf drill bits rather than custom-bored holes.
- Add a 0.5 mm chamfer to all sharp external edges. This removes burrs safely and improves handling without adding significant cost.
- Specify threaded holes with standard pitches (UNC/UNF or metric coarse). Fine threads in aluminum are prone to stripping.
- Tolerances: apply tight tolerances only to functional features. Leave non-critical dimensions at default ±0.1 mm to reduce inspection cost.
Surface Finishing Options for Aluminum
Aluminum accepts a wide range of surface finishes that enhance corrosion resistance, wear properties, and appearance. All finishing processes below are available in-house at FIRMFG.
| Process | Ra Value | Cost Index | Typical Application |
|---|---|---|---|
| Anodizing Type II (Sulfuric) | Ra 0.4 – 0.8 μm | 1.2 | Decorative color, corrosion protection, consumer enclosures |
| Anodizing Type III (Hardcoat) | Ra 0.2 – 0.5 μm | 1.8 | Wear-resistant surfaces, military, aerospace, automotive pistons |
| Bead Blasting | Ra 0.8 – 1.6 μm | 0.5 | Uniform matte finish, pre-anodize preparation |
| Powder Coating | Ra 1.0 – 2.0 μm | 1.0 | Durable outdoor finish, structural components, chassis |
| Electropolishing | Ra 0.1 – 0.3 μm | 1.5 | Medical devices, food-grade, mirror-like surfaces |
| Chemical Conversion (Chromate / Alodine) | As-machined | 0.3 | Primer base, electrical conductivity preservation, MIL-DTL-5541 |
Anodizing processes comply with MIL-A-8625 (Type II and Type III). Chemical conversion coating complies with MIL-DTL-5541, Type I and Type II. Cost index is normalized to as-machined finish (1.0 = no post-processing).
Choosing the Right Finish for Your Aluminum Part
For most aluminum parts, we recommend bead blasting followed by Type II anodizing. This combination produces a uniform, scratch-resistant surface available in clear, black, red, blue, gold, and dozens of custom colors. Type III hardcoat anodizing is preferred when the part will experience sliding contact or abrasive wear, as it builds a dense oxide layer 25-75 μm thick with surface hardness exceeding 60 HRC equivalent. If electrical conductivity must be preserved (e.g., for EMI shielding enclosures), choose chemical conversion coating instead of anodizing, since anodic oxide is an electrical insulator.
Note that 7075 and 2024 alloys anodize to a slightly darker, warmer tone than 6061 and 6063. If cosmetic color consistency across multiple alloys is critical, specify this in your drawings and our team will adjust the anodizing parameters accordingly.
What Drives Aluminum CNC Machining Cost?
Understanding the cost structure of CNC machined aluminum parts helps you optimize your design for manufacturing and reduce per-unit pricing.
Material
15 – 25%
Aluminum stock price varies by alloy and form. 6061 bar stock is the most economical; 7075 and MIC-6 plate carry a premium.
Machining
75 – 85%
Machine time, setup, programming, and tooling. This is the dominant cost driver and the primary lever for cost reduction.
Post-Processing
5 – 15%
Anodizing, powder coating, bead blasting, and inspection. Some finishes like hardcoat anodizing add notable cost and lead time.
5 Cost Reduction Strategies
Standardize alloy selection
Use 6061-T6 wherever possible — it is the most stocked, most machinable, and most cost-effective aluminum alloy.
Avoid deep pockets and tall walls
Pocket depth over 4× tool diameter requires specialized long-reach tooling. Keep depth-to-width ratios within recommended limits.
Use generous internal radii
Larger corner radii allow bigger tools that remove material faster and last longer. Every radius doubles as a cost lever.
Design for single-setup machining
Orient features so they can be machined from one side. Each additional setup adds fixture time and tolerance stack-up.
Scale to volume pricing
Ordering 10+ units spreads setup and programming costs across the batch, dramatically reducing per-unit price.
Cost Example: Same Part at Different Volumes
| Order Quantity | Unit Cost | Lead Time | Notes |
|---|---|---|---|
| 1 unit | $450 | 7 days | Prototype — full setup cost |
| 10 units | $120 | 10 days | Low-volume — setup amortized |
| 100 units | $48 | 15 days | Production — maximum efficiency |
Example based on a 6061-T6 bracket, 80 × 50 × 20 mm, with Type II anodizing. Actual quotes vary with geometry, tolerance, and finish requirements.
Aluminum CNC Machining FAQ
Answers to the most common questions about CNC machining aluminum parts at FIRMFG.
QWhat is the best aluminum alloy for CNC machining?
6061-T6 is the best general-purpose alloy for CNC machining. It offers an excellent balance of machinability, strength, weldability, corrosion resistance, and cost. For high-stress aerospace applications, 7075-T6 provides superior strength. For cast tooling plates requiring flatness, MIC-6 is preferred.
QWhat tolerances can you achieve when CNC machining aluminum?
FIRMFG achieves standard tolerances of ±0.005" (±0.13 mm) for most aluminum parts, precision tolerances of ±0.002" (±0.05 mm) for demanding applications, and high-precision tolerances down to ±0.0005" (±0.013 mm) for critical features. Tolerances are verified with CMM inspection reports.
QHow long does CNC machining aluminum take?
Standard aluminum CNC machined parts ship in as fast as 3 days for simple geometries. Complex 5-axis parts or parts requiring post-processing such as anodizing typically take 7-10 days. Production runs of 100+ units generally require 2-3 weeks. Rush service is available for urgent projects.
QCan aluminum parts be anodized after CNC machining?
Yes. Anodizing Type II (sulfuric) and Type III (hardcoat) are the most common post-machining finishes for aluminum. Type II provides decorative color and corrosion protection (MIL-A-8625 Type II). Type III hardcoat adds a wear-resistant surface up to 60+ Rockwell C equivalent. Both processes are performed in-house at FIRMFG.
QWhy does aluminum build up on cutting tools during machining?
Built-up edge (BUE) occurs when aluminum adheres to the cutting tool due to its low melting point and high ductility. It is prevented by using polished, sharp carbide tools with positive rake geometry, high cutting speeds, flood or mist coolant, and tool coatings such as TiB2 or diamond. BUE degrades surface finish and dimensional accuracy if not controlled.
QIs CNC machining aluminum expensive compared to other metals?
No. Aluminum is one of the most cost-effective metals to machine. Its excellent machinability rating (200% relative to steel) allows cutting speeds 3-5 times faster, which reduces cycle time and cost. Material cost is moderate, and tool wear is low. Overall, CNC machining aluminum is typically 30-50% less expensive than machining steel for equivalent geometries.
Industries We Serve with Aluminum CNC Machining
FIRMFG delivers precision aluminum machined parts to industries where lightweight strength, thermal performance, and dimensional accuracy are critical.
Aerospace
Aircraft brackets, structural fittings, UAV components
Automotive
Engine housings, custom mounts, EV battery trays
Electronics
Heat sinks, RF enclosures, device housings
Medical
Surgical instruments, imaging equipment, prosthetics
Robotics
Precision gears, actuator bodies, end-effectors
Consumer Products
Camera housings, sporting goods, premium enclosures
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Learn MoreStart Your Aluminum CNC Machining Project
Upload your CAD files and get a free aluminum CNC machining quote within 24 hours. Our engineers provide DFM feedback and alloy recommendations at no cost. ISO 9001 certified quality, tolerances to ±0.005", and fast turnaround starting at 3 days.