CNC Machining Methods: Milling vs. Turning – Key Differences and Applications

What is CNC Machining?

CNC (Computerized Numerical Control) machining is a manufacturing process that uses automated machine tools controlled by programmed numerical code.

By precisely cutting and shaping materials such as metals, plastics, and engineering composites, CNC machining delivers accurate, repeatable parts for industries including automotive, electronics, aerospace, and industrial equipment. Using a CNC machine, manufacturers can produce complex geometries directly from 3D CAD files, ensuring tight tolerances and consistent quality even in high-volume production.

In this guide, we compare two of the most widely used CNC machining processes — milling and turning — including their features, strengths, and limitations.

CNC 종류 선반 밀링.webp — CNC machining delivers accurate, repeatable parts by precisely cutting and shaping materials.

1. CNC Milling

CNC milling uses a rotating cutting tool to remove material from a stationary workpiece. It’s ideal for producing flat, contoured, and complex surfaces, and is widely used for automotive parts, mold components, and precision mechanical assemblies.

Capabilities by Axis Count

3-axis – Efficient for simple geometries
4-axis – Enables machining on multiple faces without repositioning
5-axis – Ideal for intricate, multi-surface geometries with fewer setups

Advantages:

High dimensional accuracy and repeatability
Flexible for a variety of shapes and sizes

Limitations:

Tool access can restrict certain geometries
May require multiple setups for deep or enclosed features

Common Milling Operations

Face Milling – Creates flat, high-precision surfaces using a multi-edge cutter; ideal for large surface removal.
End Milling – Produces detailed features such as pockets, slots, and contours with a slender, drill-like cutter.
Groove Milling – Cuts uniform-width channels, often used for keyways or assembly slots.

imgPath — Common Milling Operations include Face Milling, End Milling, and Groove Milling.

2. CNC Turning

CNC turning (or lathe machining) rotates the workpiece while a stationary cutting tool removes material. It’s the go-to process for cylindrical parts such as shafts, pins, and threaded components.

Advantages:

Fast cycle times and high productivity
Lower per-unit cost for cylindrical parts

Limitations:

Limited to rotationally symmetric geometries
Complex features may require secondary machining

Common Turning Operations

External Turning – Shapes the outside diameter of parts.
Drilling & Boring – Creates or enlarges holes; boring improves internal diameter precision.
Facing – Flattens the end surface for assembly or sealing applications.