CNC 가공 vs 3D 프린팅: 2026년 프로젝트에 어떤 것이 적합한가?

How each process works

CNC machining is a subtractive process: a computer-controlled cutter removes material from a solid block (the “billet” or “blank”) until the finished geometry remains. The machine follows a toolpath generated from a CAD/CAM file, achieving tolerances as tight as ±0.005 mm on production-grade equipment.

3D printing (additive manufacturing) builds a part layer by layer from a digital model. There are several families — FDM extrudes molten polymer, SLA cures liquid resin with UV light, SLS sinters powdered nylon, and DMLS/SLM fuses metal powder with a high-power laser. Each has its own accuracy, surface finish, and material range.

Side-by-side comparison

The table below summarises the practical differences engineers care about most. Use it as a starting point, then read the deep-dive sections for nuance.

When CNC machining wins

• Tight tolerances. Anything below ±0.05 mm is essentially CNC territory. Mating parts, bearing seats, sealing surfaces.
• Aerospace, medical, oil & gas. These sectors require certified materials with full bulk properties — Ti-6Al-4V, Inconel 718, 316L stainless — and traceability that 3D printing still struggles to match outside dedicated DMLS shops.
• Volumes above 50–100 units. CNC’s per-unit cost falls quickly with batch size; 3D printing barely improves.
• End-use mechanical loads. A milled aluminium bracket has uniform 6061-T6 strength in every direction. An FDM-printed equivalent loses 30–60% strength along the Z-axis layer interfaces.
• Smooth, paint-ready surfaces. A milled face is naturally Ra 1.6 µm or better. Most 3D-printed parts need extensive post-processing to look or feel similar.

For more on CNC tolerance capabilities, see our precision machining services page or the broader CNC machining services overview.

When 3D printing wins

• Internal lattice or conformal cooling channels. Geometry no end mill can reach — heat exchangers, lightweighted brackets, fluid manifolds with curved internal passages.
• One-of-a-kind concept models. When the design is still in flux and you want something tangible by tomorrow, FDM or SLA is unbeatable.
• Topology-optimised parts. Generative-design organic shapes that minimise mass for a given load case — common in motorsport and aerospace prototyping.
• Patient-specific medical devices. Cranial implants, dental aligners, surgical guides — every part is unique, so per-unit setup cost dominates and 3D printing wins.
• Functional polymer prototypes. SLS-printed nylon (PA12, PA11) parts can survive real-world testing and sometimes go straight to limited production.

JLYPT offers rapid 3D printing services for FDM, SLA, SLS, and metal DMLS in parallel with our CNC capacity, so you don’t have to pick one vendor per technology.

When to combine both

Many high-performance parts use both processes — additive for the complex internal feature, subtractive for the precision interface. The pattern usually looks like this:

1. 1

   3D-print the rough form

   A near-net-shape blank carrying the complex internal geometry — for example a heat exchanger core with conformal channels, printed in DMLS Inconel 718.

2. 2

   Heat-treat and stress-relieve

   Bring the additive material to its final mechanical properties; relieves residual stresses from the print process.

3. 3

   CNC the critical interfaces

   Machine all sealing faces, bearing bores, and mating surfaces to ±0.01 mm. The complex internals stay as-printed; the interfaces are CNC-finished.

4. 4

   Inspect on CMM

   Both the CNC features and the printed geometry are validated against the CAD model with full first-article inspection (FAI) documentation.

This hybrid workflow is standard for aerospace fuel nozzles, custom heat sinks, and certain medical implants. Talk to us about whether it makes sense for your part — see the contact page.

Cost deep dive

Cost comparisons published online are often misleading because they assume a single “ideal” part. In reality, three independent factors dominate:

A practical example: a small aluminium bracket, 50 × 50 × 25 mm, produced in batches.

Decision workflow

When a customer sends us a CAD file and asks “CNC or 3D print?”, we walk through these questions in order. You can do the same:

1. 1

   Is the tightest tolerance below ±0.05 mm anywhere on the part?

   If yes → CNC, or hybrid (3D print + CNC the critical features). If no → continue.

2. 2

   Does the part have internal features no end mill can reach?

   If yes → 3D printing or hybrid. If no → continue.

3. 3

   What is the production volume?

   Below 10 units → 3D printing usually cheaper. 10–50 → roughly equal, depends on complexity. Above 50 → CNC almost always wins on unit cost.

4. 4

   Does the part need certified bulk-material properties?

   Aerospace AS9100, medical implant grades, oil & gas API certifications all favour wrought/cast bar stock that CNC removes from. 3D-printed metal needs separate qualification.

5. 5

   What surface finish is required?

   Anything below Ra 3.2 µm on a complex surface usually means CNC, or 3D print + machined critical faces.