CNC Machining vs 3D Printing – What’s the Difference?

It is known that both 3D printing and CNC machining have multiple benefits over conventional machining, but what really are the differences between the two modern manufacturing methods?

Type of Manufacturing: Subtractive vs Additive.

CNC milling or machining is a form of subtractive manufacturing and works by starting with a solid material structure and systematically removing parts of it. This is conducted via pre-programmed manoeuvres carried out by spinning tools or cutters to remove unwanted parts of the material until the desired shape and design is reached.

 3D printing, however, is a form of additive manufacturing which works by placing layer upon layer of a material on top of each other, these layers are then solidified to create a design. Just like CNC machining, this is processed by reading a CAD (Computer Aided Design) file which directs the movements of the printer to create the programmed design.

 Types of materials.

CNC machining has an abundance of material available for its use. Some of these include:

  • Soft and hard woods
  • Metals: brass, copper, aluminium, titanium, steel
  • Foam
  • Fibreglass
  • Plastics: polypropylene, ABS, Nylon 6, polycarbonate

3D printing is also applicable for a plethora of materials, the most common filaments being:

  • Plastics: ABS, HIPS, PLA, Nylon, Polycarbonate, polypropylene
  • Carbon Fibre
  • Metals: copper, bronze, brass, steel
  • Wood (combined with PLA, and cork, etc)

From this we can see that there is a large overlap with the material usage, it is more the way these materials are manufactured that differs.

Which is right for the job?

Despite operating in completely different ways, CNC machining and 3D printing have quite a lot in common in terms of capabilities and material versatility, so it really comes down to what the job is that you’re looking to get done. 3D printing is a great option in regards to turnaround speed, however they do not offer quite as much dimensional accuracy as CNC machining. CNC machining is known for its excellent repeatability level and absolute accuracy.  If price is your focus then – again – it depends on the job in hand. With 3D machining you pay for the volume of the object, so it can be more cost-effective for smaller parts, but for larger objects, CNC machining is more economical.