3D Printing (Additive Manufacturing)

3D printing builds parts layer-by-layer from digital models, enabling complex geometries, fast iteration, and low-quantity production with process-dependent surface finish and tolerances.

Overview

3D Printing (Additive Manufacturing) produces parts directly from CAD by adding material layer-by-layer rather than cutting it away. It excels at complex internal features, lightweight lattices, and consolidating multi-piece assemblies into single parts, with minimal tooling and fast design iteration.

Choose it for prototypes, bridge production, and low-volume end-use parts where geometry drives value and lead time matters more than per-part cost. Tradeoffs include anisotropic mechanical properties, support structures and their removal, stair-stepping surface finish, and variable tolerances that often require secondary machining on critical datums.

Common sub-process families include Plastic 3D Printing (e.g., FDM/FFF, SLA/DLP, SLS/MJF) for fast prototypes and polymer end-use parts; Metal 3D Printing (e.g., DMLS/SLM, EBM, binder jet) for high-performance components; and Composites 3D Printing for continuous-fiber reinforcement where stiffness-to-weight is the priority.

Common Materials

  • PA12 Nylon
  • ABS
  • PETG
  • Aluminum AlSi10Mg
  • Stainless Steel 316L
  • Ti-6Al-4V

Tolerances

±0.005" to ±0.020" (often ±0.010" typical; tighter requires post-machining)

Applications

  • Form-fit functional prototypes
  • Production jigs and assembly fixtures
  • Custom end-use medical orthotics
  • Lattice lightweight brackets
  • Conformal-cooled injection mold inserts
  • Complex manifolds and ducting

When to Choose 3D Printing (Additive Manufacturing)

Choose additive when geometry is the differentiator: internal channels, undercuts, lattices, or part consolidation that would be impractical to machine or mold. It fits prototypes through low-volume production where you want short lead time and don’t want to invest in hard tooling. Plan on secondary operations if you have tight tolerances, critical sealing surfaces, or cosmetic requirements.

vs CNC machining

Choose 3D printing when the part benefits from internal features, topology-optimized forms, or part consolidation that would drive machining setups and scrap. It’s also strong for fast iteration where changing CAD daily is expected. Use machining as a follow-up for critical datums, bores, threads, and sealing faces.

vs Injection molding

Choose 3D printing when volumes are low, designs may change, or you need parts in days instead of waiting for tooling. It also helps validate geometry and function before committing to a mold. Expect higher unit cost and more variability in surface/appearance versus molded parts.

vs Casting (metal)

Choose 3D printing for intricate internal passages, very thin/complex features, or when tooling and pattern lead time would dominate the schedule. It also works for one-off or very low quantities where casting setup costs don’t amortize. Plan for post-processing to hit flatness, hole quality, and mating interfaces.

vs Sheet metal fabrication

Choose 3D printing when the part is not naturally prismatic, needs enclosed ducts/manifolds, or requires integrated mounting features that would add many secondary ops in sheet metal. It’s useful for low-volume brackets with organic geometry or weight-optimized forms. If the design is mostly bends and flats, additive loses its cost advantage quickly.

vs Urethane casting

Choose 3D printing when you need higher temperature capability, specific engineered polymers, or you want to avoid making master patterns and silicone molds. It also supports complex internal cavities that are difficult in soft tooling. Surface finish and isotropy vary by print process and may not match cast urethanes without finishing.

Design Considerations

  • Orient parts so critical features land on stable planes and minimize support contact on cosmetic or sealing surfaces
  • Add machining stock on critical datums/bores and call out post-machining requirements on the drawing
  • Avoid long, thin unsupported walls; add ribs/fillets and keep thickness more uniform to reduce warp and print time
  • Design escape holes and powder removal paths for hollow sections, lattices, and internal channels
  • Use generous radii and self-supporting angles to reduce supports and improve surface quality
  • Specify functional requirements (load, temperature, chemical exposure) so the shop can select the right process/material and build parameters