CNC machining stands as the most prevalent subtractive manufacturing technology in use today, offering immense flexibility and reliability for crafting customized metal and plastic parts. By employing CAD models, CNC machines meticulously remove material from a solid block using an array of cutting tools.

On the whole, CNC machining yields parts with precise tolerances and remarkable material properties. It is well-suited for both individual projects and low-to-medium volume production (up to 1,000 parts) due to its exceptional repeatability. Nevertheless, it does entail certain design constraints, partly due to its subtractive nature, which distinguishes it from 3D printing.

In this introductory guide, we aim to provide you with an overview of the fundamental principles of this technology, along with how these principles correlate with its key advantages and limitations. We also elucidate the primary distinctions between the two principal CNC machine configurations: milling and turning.

CNC turning machines employ stationary cutting tools to remove material from a part, which is secured on a rotating chuck. This method is ideal for producing parts with symmetry along their central axis, often resulting in faster and more cost-effective production compared to milling.

Typically, CNC turning systems, also referred to as lathes, are primarily used for crafting cylindrical parts. However, contemporary multi-axis CNC turning centers, equipped with CNC milling tools, have expanded their capabilities to manufacture non-cylindrical parts. These systems merge the high productivity of CNC turning with the versatility of CNC milling, enabling the production of a wide range of geometries with rotational symmetry, such as camshafts and radial compressor impellers.

Here is an overview of how a CNC turning machine fabricates parts:

1. The operator generates G-code instructions derived from a CAD model and loads the machine with a cylinder of stock material, often called a blank.

2. The part initiates rapid rotation at high speed, while a stationary cutting tool follows a predefined profile, progressively removing material until the desired geometry is achieved.

3. For creating holes along the central axis of the workpiece or performing internal cuts, specialized cutting tools and center drills can be employed.

4. If it becomes necessary to reposition or flip the part during the process, the aforementioned steps must be repeated. Otherwise, once the material removal process is completed, the part should be ready for use or further post-processing.

1. End Mills: These are versatile tools with cutting edges on both the end face and the sides, suitable for tasks like contouring, slot cutting, and drilling.

2. Drill Bits: Specifically designed for creating holes in the workpiece, drill bits come in various types, including twist drills, spot drills, and center drills.

3. Face Mills: These tools have cutting edges on the face of the cutter and are used for facing, profiling, and shallow pocket milling.

4. Ball Nose End Mills: Ball end mills have a rounded end and are ideal for 3D contouring, sculpting, and engraving due to their ability to create smooth curves and surfaces.

5. Roughing End Mills: These are designed for high-speed material removal, making them suitable for roughing operations.

6. Turning Tools: Used primarily in CNC turning, these tools include inserts and tool holders for creating cylindrical parts.

7. Boring Bars: Boring bars are utilized for enlarging existing holes and achieving high precision in hole machining.

8. Threading Tools: Thread mills and taps are employed for creating threads in the workpiece.

9. Reamers: Reamers are used to achieve precise and smooth hole finishes after initial drilling.

10. Chamfer Mills: These tools are employed to add chamfers or bevels to the edges of the workpiece.

11. Counterbore and Countersink Tools: These tools are used for creating counterbores (enlarged holes with a flat bottom) and countersinks (angled depressions at the opening of a hole), respectively.

The choice of cutting tool depends on the specific machining operation and the material being worked on. CNC operators select the appropriate tool based on factors such as cutting speed, feed rate, depth of cut, and the desired finish.