3D Printing vs CNC Machining — What’s the difference?
3D printing has been trending lately due to its rapid technological growth. This results in major advantages of 3D printing over traditional manufacturing methods. However, it does have its own problems. Some of the disadvantages it has are the inability to mass manufacture due to its limitations in speed and accessibility.
The differences between 3D printing and CNC machining are — the type of manufacturing, type of materials, ease of use, technicality, costs, and environmental friendliness.
Type Of Manufacturing
The key difference between 3D printing and CNC machining is that both use different types of manufacturing. 3D printing, also called additive manufacturing, involves printing parts layer by layer using materials such as plastic filaments, resins, or metal powders. Using a source of energy such as laser or heated extruder, these materials are solidified to form the finished part.
CNC machining, also called subtractive manufacturing, involves cutting down a black material to form a finished part. To do this, cutters and spinning tools are used to shape the piece.
Materials
Both 3D printing and CNC machining are able to manufacture using plastic or metals. However, 3D printing is more suited towards using plastic although this is changing as more advances are in the works for 3D printing machines to manufacture using metals.
The most commonly used plastic in CNC machining includes ABS, Nylon (PA66), Polycarbonate (PC), Acrylic (PMMA), Polypropylene (PP), POM, and PEEK. The most common metals used for CNC machining are aluminum, stainless steel, magnesium alloy, zinc alloy titanium, and brass.
Ease Of Use
3D printing is much easier to use as once the part is designed and uploaded. The machine will start printing it without the need of a supervisor until the part is completed.
CNC machining is a far more labor-intensive process. A skilled operator is required to choose the different tools, the rotation speed of tools, the cutting path, and any repositioning of the material the part is created from.
Technicalities
Though there are a number of 3D printing technologies, we have chosen to compare CNC machining with SLS, industrial (not desktop) FDM, and DMLS metal 3D printing. In terms of tolerance, CNC machining is superior to all 3D printing processes, even DMLS. However, with minimum layer thicknesses, the superiority is not so profound and is not as precise as DMLS.
Powder bed fusion 3D printing processes such as SLS and DMLS are limited in their build volume, however. Even technologies with larger build volumes such as FDM cannot compete with CNC in terms of the maximum size of parts.
3D printing is well-known for its advantages in creating parts with high geometric complexity. Though supports are required for some technologies, 3D printing can create parts with geometries that no traditional manufacturing method can replicate. Technologies such as SLS and Multi Jet Fusion by HP can even do this without any support structures.
Cost
Though on average 3D printing is cheaper, costs depend on how many parts are required and how quickly you need them. For larger quantities (higher double digits to 100s) CNC is likely to be more appropriate. For low volumes, 3D printing is more appropriate and lower-cost. 3D printing is also more appropriate if you need your prototypes or parts very quickly. There are additional factors however that make comparing the two technologies more difficult. These include materials varying in cost (from cheap materials like ABS to materials that can cost $500/kg like PEEK), and repairing and changing machinery (such as CNC heads).
Environmental Friendliness
Since CNC involves cutting material away from an original block, there is always going to be a mess afterward. These pieces of material need to be cleaned afterward and disposed of, which isn’t required from 3D printing. Since additive manufacturing forms an object on the build platform from material fed into the machine, there is no mess except supports (if used). This makes 3D printing the more ethical of the two methods as there is less unused waste.
Conclusion
Overall to conclude, there is no perfect, one-size-fits-all technique. Though both methods are very competent and useful technologies, the most appropriate one will depend on the material, geometric complexity, manufacturing volume, and budget. To find out which is best for your particular job, we advise you to approach Robo CNC which is the HAAS Factory Outlet in Malaysia with industry experts with over 20 years of experience.
