Choosing between 3D printing and CNC machining for prototyping is one of the most common decisions product development teams face. Both have strengths, and the right choice depends on your specific requirements.
3D printing (additive manufacturing) builds parts layer by layer from digital files. It excels at complex geometries, internal channels, lattice structures, and organic shapes that would be impossible or extremely expensive to machine.
CNC machining (subtractive manufacturing) cuts material from a solid block. It produces parts with superior surface finish, tighter tolerances, and in production-grade materials. If your prototype needs to function like the final product, CNC is often the better choice.
Cost comparison: For single prototypes with complex geometry, 3D printing is almost always cheaper ($50-$500 per part). CNC machining has higher setup costs ($500-$5,000+) but becomes cost-effective at 10+ units due to faster per-part production.
Speed comparison: 3D printing wins for quick turnaround. Most parts can be printed overnight (12-24 hours). CNC machining requires programming, fixturing, and machining — typically 3-5 days for a single part.
Material comparison: CNC machining works with the actual production materials — aluminum, steel, titanium, engineering plastics. 3D printing materials are improving but still don't match the mechanical properties of machined metals in most cases.
Tolerance comparison: CNC machining routinely achieves ±0.025mm. FDM 3D printing is ±0.3mm. SLA resin printing achieves ±0.1mm. MJF/SLS powder printing is ±0.1-0.2mm. For precision parts, CNC is the clear winner.
Surface finish: CNC parts have excellent surface finish straight off the machine (Ra 0.8-3.2 μm). 3D printed parts typically require post-processing (sanding, painting, vapor smoothing) to achieve comparable finish quality.
Our recommendation: Use 3D printing for concept validation, form checks, and complex geometries. Use CNC for functional prototypes, parts that will be tested under load, and when material properties matter. Many projects benefit from using both at different stages.