Aerospace machining isn’t just CNC machining with tighter tolerances. It’s a different category — different materials, different documentation requirements, different consequences for getting it wrong. If you’re sourcing aerospace components, here’s what you need to know about the materials, tolerances, and certifications that separate aerospace-grade work from everything else.

What Makes Aerospace Machining Different

Every industry cares about quality. Aerospace cares about traceability. The difference is significant: a machined bracket for a warehouse shelf needs to hold weight. A machined bracket for a flight-critical aircraft assembly needs to hold weight, AND you need to prove — with documentation — that the material came from a certified mill, was machined within specified parameters, was inspected at defined intervals, and meets every dimensional and surface finish callout on the drawing.

That documentation chain isn’t optional. It’s the cost of doing business in aerospace, and it’s why aerospace parts cost more than visually identical commercial parts.

Aerospace Materials and Why They’re Challenging

Aluminum Alloys

Aluminum is the workhorse of aerospace structures, but not the 6061 you’d use for a general-purpose bracket. Aerospace aluminum means:

  • 7075-T6 — The standard for structural aerospace components. High strength-to-weight ratio (83 ksi ultimate tensile strength), excellent fatigue performance. Machines well but requires sharp tooling and appropriate feeds/speeds to avoid work hardening at the cut surface.
  • 2024-T3 — Superior fatigue resistance, widely used in fuselage and wing skins. Slightly more difficult to machine than 7075 due to higher ductility — chip control matters.
  • 6061-T6 — Used in secondary structures and non-critical brackets. The easiest aerospace aluminum to machine, but rarely specified for primary structure.

Titanium Alloys

Titanium is where aerospace machining gets expensive. Ti-6Al-4V (Grade 5) is the dominant aerospace titanium alloy — outstanding strength-to-weight ratio and corrosion resistance, but notoriously difficult to machine:

  • Low thermal conductivity means heat concentrates at the tool tip rather than dissipating through the chip
  • Chemical reactivity with tool materials causes rapid tool wear
  • Spring-back during machining affects dimensional accuracy
  • Cutting speeds are typically 50-80% slower than stainless steel

Shops that machine titanium well have invested in rigid machine tools, high-pressure coolant systems, and hard experience. It’s not a material you learn on.

Nickel Superalloys (Inconel, Waspaloy, Hastelloy)

These alloys maintain strength at extreme temperatures — 1,000°F+ — which makes them essential for jet engine components and exhaust systems. They also maintain their hardness at the cutting temperature, which means they fight the tool at every point in the cut. Machining Inconel 718 requires ceramic or CBN tooling, extremely rigid setups, and tolerance strategies that account for significant tool deflection and wear.

Specialty Steels

High-strength steels like 4340, 300M, and maraging steels are used in landing gear, actuators, and other high-load aerospace components. These are typically machined in a pre-hardened state (Rc 28-35), then heat treated to final hardness (Rc 50-55), then finish-machined or ground to final dimensions.

Tolerances in Aerospace Work

Commercial machining typically works to ±0.005″ or ±0.003″. Aerospace routinely requires ±0.001″ on critical features, with some bore and shaft fits calling for ±0.0005″ or tighter.

But aerospace tolerances aren’t just about numbers on a print. They involve:

  • True Position — Bolt hole patterns on aerospace parts are called out with true position tolerances referenced to datum features. This is GD&T (Geometric Dimensioning and Tolerancing) per ASME Y14.5, and it requires CMM inspection to verify.
  • Surface Finish — Surface roughness callouts on fatigue-critical features are taken seriously. A 32 Ra finish vs. a 16 Ra finish can significantly affect fatigue life on a cyclic-loaded component.
  • Edge Break Requirements — Aerospace drawings typically call out specific edge break radii (0.005″–0.030″ typical) on all machined edges. Sharp edges are stress concentrators and fatigue crack initiation sites.
  • Residual Stress — Aggressive machining parameters can induce tensile residual stresses at the surface, reducing fatigue life. Some aerospace specs require shot peening or specific machining strategies to ensure compressive residual stress at critical surfaces.

Certifications and Quality Systems

AS9100

AS9100 is the aerospace-specific quality management system standard, built on ISO 9001 with additional requirements for risk management, configuration management, and product safety. If you’re supplying parts to an aerospace OEM or Tier 1 supplier, AS9100 certification is typically the minimum requirement.

NADCAP

NADCAP (National Aerospace and Defense Contractors Accreditation Program) accredits specific processes — heat treating, chemical processing, non-destructive testing, welding. If your part requires any special process, the shop performing that process typically needs NADCAP accreditation for it.

First Article Inspection (FAI)

Aerospace customers almost universally require First Article Inspection per AS9102. This is a complete dimensional inspection of the first production part, documented in a standardized format. Every dimension, every note, every material certification — verified and recorded. A typical FAI package for a moderately complex aerospace part runs 20-50 pages.

Material Certifications

Aerospace material must come with mill certifications (certs) tracing back to the original melt. The cert documents the material chemistry, mechanical properties (tensile, yield, elongation, hardness), heat/lot number, and applicable specifications (AMS, ASTM). Raw material without certs is scrap in aerospace — even if it tests to spec.

Common Aerospace CNC Components

The range of CNC-machined aerospace parts is enormous, but common categories include:

  • Structural brackets and fittings — Aluminum and titanium, connecting airframe components
  • Engine mounts and housings — High-strength steel and nickel alloys, tight-tolerance bores
  • Actuator components — Hydraulic and electromechanical, demanding concentricity and surface finish
  • Landing gear components — High-strength steel, large parts, critical fatigue requirements
  • Avionics enclosures — Aluminum, complex pocket milling, EMI shielding requirements
  • Turbine components — Nickel superalloys, extreme precision, exotic tooling
  • Satellite and spacecraft hardware — Ultra-lightweight aluminum structures, often machined from solid billets with 90%+ material removal

What Drives Aerospace Machining Cost

Aerospace parts routinely cost 3-10x more than visually similar commercial parts. Here’s where that cost comes from:

  1. Material cost — Aerospace-grade material with full traceability costs significantly more than commercial grades. Ti-6Al-4V bar stock runs $15-25/lb compared to $1-3/lb for 6061 aluminum.
  2. Slower machining — Tighter tolerances and difficult materials mean slower feeds, lighter cuts, and more passes. A titanium part might require 3-5x the machine time of the same geometry in aluminum.
  3. Inspection time — CMM inspection, FAI documentation, and quality review can equal or exceed the machining time itself.
  4. Tooling consumption — CNC tooling for titanium and nickel alloys wears rapidly. Tool changes and the cost of premium tooling add up.
  5. Setup and programming — Complex five-axis parts require extensive CAM programming and prove-out time.

How to Choose an Aerospace Machine Shop

When sourcing aerospace machined components, look for:

  • AS9100 certification (or willingness to work within your quality system if certification isn’t strictly required)
  • Demonstrated experience with your specific material — ask for examples
  • CMM capability with calibrated equipment and competent operators
  • Understanding of GD&T and ability to interpret aerospace drawings correctly
  • Willingness to provide full documentation packages (FAI, material certs, process records)
  • Capacity for your production volumes and delivery timeline

A shop that gives you a great price but can’t produce an FAI report isn’t saving you money — it’s creating a problem you’ll discover at incoming inspection.

Get a Quote for Aerospace Machining

DFW Machine connects you with aerospace-capable machine shops in the Dallas-Fort Worth area and beyond. Whether you need prototype quantities or production runs, we match your requirements to shops with the right equipment, materials expertise, and quality certifications. Request a quote with your drawings and specifications — we’ll get back to you within 48 hours.