For engineers designing small, complex, and high-performance components, traditional methods like CNC milling often come with limitations. As industries demand tighter tolerances and faster turnaround, 3D printing – particularly micro-precision 3D printing – is emerging as a powerful alternative.
In this post, we break down the critical differences between CNC milling and 3D printing, including use cases, tolerances, speed, and scalability – so you can decide what’s best for your application.
What Is CNC Milling?
CNC (Computer Numerical Control) milling is a subtractive manufacturing process that removes material from a solid block (often metal or plastic) using rotating cutting tools. It’s widely used in aerospace, automotive, and medical industries for parts that require structural integrity and tight tolerances.
Pros of CNC Milling:
- High accuracy for certain geometries
- Broad material compatibility
- Excellent surface finish for larger features
Challenges:
- Tool access limits design freedom
- Long setup times for small batches
- Not ideal for internal micro-features or very small parts
What Is 3D Printing?
3D printing (additive manufacturing) builds parts layer by layer from digital models. Technologies vary widely – from FDM and SLA to specialized systems like Projection Micro Stereolithography (PµSL), which BMF uses to print micro parts with micron-level precision.
Advantages of 3D Printing:
- Complex, organic geometries are easy to achieve
- No tooling or fixturing required
- Ideal for fast prototyping and on-demand production
Limitations:
- Surface finish may require post-processing
- Material options can be limited depending on the technology
- Tolerances vary based on the system used
When 3D Printing Wins: Micro-Scale, High-Precision Parts
For parts smaller than a dime with features in the tens of microns, CNC milling hits a wall. Tooling can’t reach tiny internal channels, and material waste becomes a concern. That’s where BMF’s micro 3D printing platform excels.
Use cases include:
- Endoscope tips with embedded fluid channels
- Microfluidic chips with intricate pathways
- Microneedle arrays for transdermal drug delivery
- MEMS packaging and micro-electronics housings
With ±10μm tolerances and feature sizes down to ±2μm, BMF’s technology enables innovation in areas CNC simply can’t reach.
Cost and Time Considerations
CNC’s tooling setup makes small-batch production expensive and time-consuming. In contrast, micro 3D printing eliminates tooling altogether, reducing both cost and lead time.
- Prototyping: Go from CAD to part in under a day
- Iteration: Rapidly test and revise designs
- Production: Scale with confidence—print hundreds of parts in a single run
Can They Work Together?
- Many teams use CNC milling for large-scale structural parts and micro 3D printing for complex internal features, tight spaces, or integrated components that would otherwise require assembly.
- This hybrid approach is especially effective in MedTech, microelectronics, and research settings.
Choosing between CNC milling and 3D printing comes down to your part size, geometry, material needs, and production volume. For applications that require micro-scale precision, 3D printing – particularly PµSL technology from BMF – opens the door to geometries and tolerances that CNC simply can’t deliver.
Want to learn more?
Explore our application gallery or contact us to see how BMF can support your next microfabrication project.
