CNC Machining vs 3D Printing

When choosing a manufacturing process for your next project, should you go with CNC machining or 3D printing? Both methods offer distinct advantages and are widely used in everything from rapid prototyping to full-scale production. 

This depends on your needs, speed, material properties, surface finish, part complexity, or cost. One might suit your project better than the other.

In this guide, you’ll learn the key differences between CNC machining and 3D printing, how each process works, what they're best suited for, and how to choose the right method for your specific application. 

If you’re creating a one-off prototype or producing hundreds of end-use parts, this article will help you make a more informed decision.

What is CNC Machining?

CNC (Computer Numerical Control) machining is a manufacturing process that uses automated CNC machines to precisely cut and shape materials.

It involves using automated CNC machines such as mills, lathes, or routers to remove material from a solid block and shape it into a precise component. 

The process begins with programmed instructions created via a CAM software that controls the movement of tolls & machinery. 

CNC programming is now digitally entered and stored in the machine’s memory which allows for improved flexibility, editing and complexity in operations. 

By automating previously manual and physically demanding tasks, CNC machining has significantly improved efficiency, safety, and precision in modern manufacturing environments.

What is 3D Printing?

3D Printing is a process of creating three dimensional objects from digital files by layering material one cross section at a time. 

3D printing builds parts by stacking and fusing successive layers with minimal material waste. The range of printable materials continues to expand, including plastics, resins, metals, and composites.

While most 3D printing relies on layer-by-layer fabrication, one exception is volumetric 3D printing, which forms entire structures simultaneously. However, this technology remains in the early research phase.

Due to its design flexibility and efficiency, 3D printing is now a staple in engineering, aerospace, medical, and manufacturing sectors.

How does CNC Machining Work? 

CNC Machining works by using computer guided tools to remove material from a solid block, creating parts with precise dimensions. 

The process starts with a CAD model which defines the final geometry of the part, the model is then imported into CAM software, which generates the G-code instructions that control the CNC machine’s movements. 

Once the program is uploaded, the machine uses servo motors and drive systems to move cutting tools along X, Y and Z axes. 

These movements allow for precise milling, turning, or drilling operations based on the part design. The cutting tools follow the programmed tool paths, removing material in a controlled and repeatable way.

CNC machining primarily relies on two techniques: milling and turning. Together, these methods enable a wide range of geometries and finishes.

To program CNC machines, you need specialised software and someone trained to set things up properly. This makes it possible to create accurate parts quickly and efficiently. 

If you're new to the process, taking a CNC training course is a great way to build the skills needed to operate and program these machines effectively.

How Does 3D Printing Work?

3D printing begins with a 3D model that is sliced into thin horizontal layers. These layers guide the printer in constructing the object from the ground up. 

Different 3D printing technologies vary based on the form of raw material, how it’s delivered, and how each layer is fused. 

3D printing technologies fall into seven main categories such as VAT photopolymeristation, powder bed fusion, binder jetting to name just a few. 

Each method alongside countless others have specific advantages depending on material, precision, costs and intended application.

Comparing manufacturing workflows for 3D printing and CNC machining

Understanding how each workflow operates helps clarify which process best suits your project. Below are the key differences and similarities between CNC Machining and 3D Printing:

Shared Features

• Both begin with a 3D CAD model. 3D printing uses slicing software, while CNC machining relies on CAM software to generate instructions.

• Each process uses computer-controlled machines to manufacture parts with minimal manual input.

• While CNC machining offers tighter tolerances, modern 3D printers can also achieve impressive accuracy. Both methods are reliable for repeatable results. 

• Both can be used for one-off prototypes or scaled production depending on the application and material needs.

Key Differences

• 3D printing adds material layer by layer to build a part. CNC machining removes material from a solid block to shape the final component.

• 3D printing is quick to set up whereas CNC machining requires more setup such as tool selection, calibration and securing the workpiece

• 3D printers use materials like filament, resin, or powder. CNC machines work with solid blocks of plastic, metal, or other rigid materials.

• In 3D printing, the print head moves to deposit material. In CNC machining, cutting tools follow programmed paths to carve the shape.

• 3D printing allows for more complex shapes, including internal features and overhangs. CNC is better suited to simpler, more accessible geometries.

CNC vs 3D printing: Selecting The Right Process for Your Project

Precision and Surface Quality

CNC machining is known for its ability to achieve extremely tight tolerances and smooth surface finishes. It's ideal for applications where exact dimensions are critical. 

3D printed parts often have visible layer lines and may require post-processing to achieve similar surface quality. 

Material Options and Strength

CNC machining supports a broad range of materials, including high-strength metals and engineering-grade plastics. Because it uses solid blocks, the material properties remain intact. 

3D printing also offers a growing list of materials, but parts may lack the mechanical strength of their machined counterparts, particularly under stress or heat.

Cost and Waste Efficiency

For low-volume production or one-off parts, 3D printing is often more affordable, especially since it doesn’t require costly tooling. It also produces very little waste. 

CNC machining is more efficient for higher volumes due to faster cycle times and material versatility. However, it generates more scrap, especially when cutting from large blocks.

Which is more cost effective between CNC Machining vs 3D Printing?

The cost-effectiveness of each process depends on project volume, complexity, and material. 

For single prototypes or complex geometries, 3D printing generally offers lower upfront costs due to minimal setup and tooling. 

CNC machining becomes more economical at scale, especially for metal parts or when high precision is required.

While 3D printing reduces material waste and offers design freedom, CNC machining delivers faster production speeds and better unit costs at higher volumes. 

The main things to consider is your budget, design and production goals when determining which method provides the best value.

Comparing Use Cases for CNC Machining and 3D Printing

Both CNC machining and 3D printing have specific use cases based on the material, function, and desired finish of a part. 

Here are some typical applications:

Common CNC Machining Applications

• CNC routers are widely used in woodworking to cut, carve, and shape timber with extreme precision. Ideal for cabinetry, signage, and furniture production.

• CNC laser cutters can engrave detailed designs into wood, plastic, glass, and metal which is useful for personalisation, branding, or decorative finishes.

• Used in automotive, aerospace, and medical sectors for creating strong, accurate components.

Common 3D Printing Applications

• Quickly visualise and test product ideas before investing in final production.

• Ideal for creating lightweight, geometrically complex parts not easily machined.

• Used to produce patient-specific surgical guides or prosthetics.

• Great for producing low-volume, made-to-order components.

Each method shines in different scenarios, and in some workflows, they're even used together, 3D printing for concept validation, followed by CNC machining for durable, final parts.

Ultimately, CNC machines are used for a wide range of tasks, from cutting and carving wood to engraving designs for brands in industries such as automotive, aerospace and healthcare. 

CNC Machining with Onefinity CNC

Both CNC Machining and 3D printing offer unique strengths, and the right choice depends on your project’s goals. 

CNC machines are typically used for precise and durable production, especially in industries like aerospace, automotive, and woodworking. Meanwhile, 3D printing is excellent for bringing rapid design iterations to life and creating intricate shapes that subtractive tools can’t easily achieve.

If you’re interested  in turning CNC machining into a business, it’s now more accessible than ever. Onefinity provides CNC machines for beginners and small business owners.

We focus on building your skills through training and small projects, with our very own educational resource section. With growing demand for bespoke, high-quality products, a CNC side hustle has the potential to grow into a profitable full-time venture.

Join our community forum for more tips, inspiration, and support as you dive into your CNC journey.