From Printer to Spindle: How Aerospace Components Actually Get Made

For more than a decade, 3D printing—also known as additive manufacturing—has been positioned as the future of aerospace production. With a unique capability to produce complex forms at unparallelled speed, additive manufacturing promised increased production, fewer constraints and an innovative way to manufacture flight-critical parts.

In theory, additive manufacturing offered aerospace a workaround for traditional constraints. Complex internal geometries, reduced material waste and unprecedented design freedom seemed poised to redefine the production process when it came to aircraft parts.

But in aerospace, technology needs more than just promise.

Why Accessibility Created Unrealistic Expectations

Part of additive manufacturing’s challenge is a result of its own success. The catch-22 is this: Entry-level and hobby-grade 3D printers have lowered the barrier to entry so significantly that some engineers and designers assume the technology will scale seamlessly. This assumption has gotten a foothold across industries.

However, printing a part and producing a qualified, dimensionally precise, structurally reliable component are two fundamentally different challenges. Aerospace parts must meet demanding requirements for tolerance, surface finish, strength and repeatability.

In metal additive applications, that reliability often depends on post-processing steps such as heat treatment and Hot Isostatic Pressing (HIP), which use high temperature and pressure to eliminate internal porosity and improve fatigue strength. These steps are essential for flight-critical parts, but they do not eliminate the need for precision machining. While there is a widespread belief (or hope) that additive manufacturing can serve as a single, end-to-end production solution in aerospace – in reality, it cannot.

Additive’s Real Strengths and Limits

Discernment is key here. A realistic take on additive manufacturing’s limits is important, but it doesn’t diminish the value of this approach when utilized appropriately. Where does additive excel? In rapid iteration, early-stage prototyping, weight reduction and the creation of internal geometries that would be impossible or impractical to machine traditionally.

READ MORE: Beyond Traditional Machining: Hitting All the Right Notes in Custom Manufacturing

Where additive falls short is at the finish line. Flat faces, tight tolerances, controlled surface finishes and consistent geometric accuracy remain difficult to achieve with additive alone and particularly at the scale required for aerospace. These are not secondary requirements; they are fundamental to safety, performance and certification.

Even after HIP strengthens the material internally, dimensional shifts can occur during thermal processing. Critical interfaces, sealing surfaces and precision bores still require subtractive machining to meet aerospace-grade specifications.

This is where CNC machining comes in as the essential foundation that turns innovative designs into airworthy parts.

CNC Remains the Manufacturing Standard

Nearly every successful aerospace project relies on CNC machining at some point. CNC machining—also known as subtractive manufacturing—allows parts to meet ​tolerance requirements, achieve proper surface finishes and satisfy the exacting standards demanded by flight-critical applications.

In practice, additive manufacturing isn’t a replacement for CNC manufacturing, and it also tends to be more expensive. What additive should be is a complementary approach within existing manufacturing processes. In aerospace today, subtractive manufacturing remains the standard. In fact, it is subtractive manufacturing that makes parts created through additive manufacturing usable on an actual functioning assembly.

The Rise of Hybrid Manufacturing Workflows

The future isn’t additive versus subtractive—it’s additive plus subtractive, each doing what it does best. In hybrid workflows, parts are printed to leverage additive’s geometric freedom, then machined to meet aerospace-grade tolerances and finishes.

This sequence (print, HIP, machine) reflects the practical reality of aerospace production. Additive provides near-net shape and internal complexity. HIP ensures material integrity and fatigue performance. CNC machining delivers dimensional accuracy and surface control.

The result is the best of both approaches: design innovation without compromising the precision that keeps aircraft in the air.

Hybrid only works when engineers understand both sides. Without machining knowledge, it’s easy to design parts with sharp internal corners, impossibly tight tolerances or features that balloon costs without improving performance. The most effective hybrid programs are built by teams fluent in both additive possibilities and subtractive realities.

This reflects a broader truth in aerospace manufacturing: The right tool must be chosen for each stage of production. Additive opens new design territory. CNC machining makes those designs flyable. Until additive can consistently meet aerospace certification requirements on its own, CNC will remain the essential second half of that equation.

What Actually Delivers in Aerospace

Additive manufacturing will continue to evolve, and it should. The technology has earned its place in aerospace for prototyping, weight reduction and geometric innovation. But when it’s time to deliver parts that meet tolerance, pass inspection and perform under the demands of flight, CNC machining remains the standard.

The most successful aerospace programs aren’t waiting for additive to catch up. They’re building hybrid workflows that leverage both technologies for what they do best. Additive pushes design boundaries. CNC machining turns those designs into certified, flyable hardware.

That’s not legacy thinking. That’s how aerospace parts actually get made.