What is the difference between CNC and stamped metal?

Aug 01, 2025 Viewd 82

1. CNC Machining (Computer Numerical Control)

Definition:

CNC machining is a precise, computer-controlled manufacturing process that removes material from a solid block (called a billet or workpiece) using cutting tools. Machines like lathes, mills, and routers are guided by a programmed code (G-code), which defines tool paths, speed, and depth.

Process:

  • A 3D CAD model is created.
  • The model is converted to a G-code program.
  • A machine uses tools (cutters, drills, etc.) to cut the material based on this code.
  • The result is a high-precision finished part.

Types of CNC Machines:

  • CNC milling machines (for cutting complex 3D shapes)
  • CNC lathes (for cylindrical parts)
  • CNC routers (for softer materials)
  • CNC EDM (Electrical Discharge Machining) for very fine details

2. Metal Stamping

Definition:

Metal stamping is a high-speed forming process that uses a punch and die to shape flat metal sheets into desired parts. It's usually done with a hydraulic or mechanical press and is suitable for mass production.

Process:

  • A metal sheet is placed between a die and a punch.
  • The press applies force, bending or cutting the metal into shape.
  • Multiple operations (like punching holes, bending, embossing, and forming) can happen in one stroke or progressive steps.

Types of Stamping:

  • Blanking: Cutting a flat shape from the sheet.
  • Punching: Removing sections from the sheet.
  • Bending: Forming angled parts.
  • Deep Drawing: Creating hollow or cup-shaped parts.

Key Differences Between CNC and Stamped Metal

Category CNC Machining Metal Stamping
Process Type Subtractive (removes material) Formative (shapes material with force)
Material Used Solid blocks or rods (billets) Flat sheet metal
Precision Very high (up to ±0.001") Moderate to high, depends on tooling
Tooling Cost Low to medium High (custom dies are expensive)
Per-Unit Cost High for large volumes Very low for large volumes
Setup Time Short (after programming) Long (tooling and die creation takes time)
Best For Prototypes, low-volume, complex shapes Mass production of simple to moderately complex parts
Design Flexibility Very high (easy to change code) Low (changing dies is expensive and time-consuming)
Speed Slower than stamping Very fast for large batches
Material Waste Higher (material is cut away) Lower (more efficient use of sheet metal)
Surface Finish Excellent, depending on tooling and process May require secondary operations (deburring, finishing)

When to Use CNC Machining

Use CNC machining when:

  • You need tight tolerances and complex geometries.
  • The part is low to medium volume, such as prototypes or small production runs.
  • You need frequent design changes or customizations.
  • You’re working with a wide variety of materials, including metals, plastics, and composites.

You require parts with excellent surface finish or internal features (e.g., threaded holes).

When to Use Metal Stamping

Use stamped metal when:

  • You’re producing high volumes of parts with repetitive geometry.
  • Parts can be made from sheet metal and don’t need deep or complex 3D shaping.
  • You want to minimize per-unit cost.
  • Speed and efficiency are priorities.

You’re working in industries like automotive, electronics, or appliances, where millions of identical parts are needed.

Example Use Cases

Industry CNC Machining Examples Metal Stamping Examples
Aerospace Turbine blades, brackets, structural parts Light housings, clips
Automotive Engine components, gear housings Body panels, seat brackets, battery enclosures
Medical Devices Surgical instruments, implants Disposable cases, shields
Electronics Heat sinks, custom enclosures Connectors, mounting plates
Prototyping One-off or iterative design parts Rarely used unless testing stamping tools
  • CNC machining is about precision, flexibility, and complexity.
  • Metal stamping is about speed, efficiency, and high-volume production.

If you're making a few complex parts, go with CNC.

If you're making millions of identical sheet metal parts, choose stamping.

CNC and Stamped Parts