Here we present some of the main advantages of CNC machining compared to other manufacturing processes such as 3D printing, injection molding, urethane casting, laser cutting, plasma cutting, or other sheet metal fabrication processes.
Cost-efficient:
The CNC machining process is a high-speed manufacturing process for certain types of parts. CNC machines with a powerful spindle and good machine tools allow us to remove raw material fast. If the part geometry is simple (for example, a solid base plate which needs holes, threads, steps, or grooves) very small amounts of raw material are removed. In this case, the unit price for CNC machining will be much lower than 3D printing, because it would take many hours to print such a part.
More precise:
On a good CNC mill or lathe, the machine tolerance is +/-0.005 mm, and if we can remove 0.005 mm in the final cut from the workpiece, that means we can easily get parts machined with a +/-0.01 mm tolerance. Compare this to the 3D printing process, in which parts are printed layer by layer. The minimum layer height is 0.05 mm, which means the parts tolerance can’t be less than 0.05 mm.
Better for surface finishing:
Post-processing is always needed for cosmetic parts, so it is very important to achieve a good surface finish at the first stage. When the RPM of the CNC mill goes up to 15,000 and the CNC lathe up to 6,000, the CNC machined part surface roughness is less than Ra 0.8, which is good for bead blasted, painted, or anodized surfaces without sanding manually. Meanwhile for parts made from SLS, SLM, or DMLS processes, the surface roughness is far more than Ra 3.2.
More flexible part sizes:
A large CNC machine center can have a table measuring 6 m x 30 m or larger, which means that very big parts can be milled. And as far as we know, the biggest lathe was built with a maximum 5 m diameter. At the other end of the scale, with precise 5-axis CNC Mills and R0.05 mm cutting tools, we can mill a tiny geometry from a 1 mm x 1 mm x 1 mm