3D printing vs machining

3D Printing vs CNC Machining

3D printing and CNC machining are often pitched against each other but are complementary tools suited to different applications.   

We are often asked whether 3D printing will replace CNC machining. Our answer is always the same – “no” in general, but “yes” in applications where machining is expensive, time-consuming, and mechanically limited.

Both can produce parts from metals and polymers, so choosing to use one process over another comes down to cost, time, geometric complexity, and surface quality requirements.

This article explores the most significant differences between 3D printing and machining to bring balance to the argument.

Subtractive vs additive manufacturing

The fundamental difference between 3D printing and CNC machining is that 3D printing is an additive process, and CNC machining is a subtractive process.

These are opposites, and the difference is simple:

  • Subtractive manufacturing starts with a block of material (a blank) and removes it in layers to create the final object.
  • Additive manufacturing builds objects in layers from a seed material, with successive layers creating the final object.

In other words, additive manufacturing adds material to build objects, while subtractive manufacturing takes material away.

3D printing advantages

3D printing can produce more complex shapes and geometries than machining because it creates objects from scratch. With no solid material to strip away, it can produce overhangs, undercuts, and cavities CNC machining can’t.

Additionally, most 3D printers produce feature sizes from 0.1 mm (100 microns) versus CNC machining’s minimum feature size of around 0.78mm.

These significantly thinner layers have several additional advantages, including lower material waste, the potential to slash part weight, and infill potential, giving engineers a way to increase mechanical qualities beneath the surface.

Rapid prototyping is another advantage unique to 3D printing, offering the ability to send CAD drawings directly to print to get parts on the same day.

3D printing is cheaper and more capable than CNC machining for prototyping and manufacturing complex components on a small scale.

CNC machining advantages

CNC machining is significantly faster than 3D printing, making it the more suitable technology for medium to high-volume production runs.

CNC machining

Faster production speeds make CNC better suited to mass production, except when geometric complexity overwhelms the technology.

Another advantage is precision and accuracy. CNC machining can remove material much faster and more accurately than 3D printing can deposit it, making it the better option for precision components.

Milling

However, CNC machining’s most significant advantage for manufacturers is the ability to produce much larger components. 3D printers have a restricted build volume, usually less than an industrial CNC mill.

3D printing is the more flexible and versatile manufacturing tool for rapid prototyping and small series production, while CNC machining works better at scale.

Which is best for you?

3D printing is optimal in these situations:

  • Small series production.
  • You need a fast turnaround time.
  • Rapid prototyping.
  • You need parts that aren’t machinable, like TPU and silicone.
  • CNC machining can’t produce the necessary geometric complexity.

CNC machining is best in these situations:

  • You need maximum tolerance.
  • Medium and large-scale production.
  • Manufacturing giant components.
  • You need hundreds or more identical parts.

Mostly, your answer comes down to production volume and geometric complexity requirements.

Find out more

To find out more about 3D printing and its potential to replace CNC machining, please get in touch with the team at 01765 694 007, email team@additive-x.com, or you can

 

 

 

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