3D print

To 3D print is to fabricate a solid three-dimensional object by depositing or curing material in successive layers, guided by a digital model. The process converts a CAD file into physical form without tooling, molds, or subtractive waste. A 3D printer reads the model, slices it into thin horizontal cross-sections, and builds each layer on top of the previous one until the part is complete. The result is a finished or near-finished component, prototype, or tool.

The most common industrial methods are fused deposition modeling (FDM), where a heated nozzle extrudes thermoplastic filament; selective laser sintering (SLS), which fuses powdered polymer or metal with a laser; stereolithography (SLA), which hardens liquid resin with ultraviolet light; and binder jetting, which deposits adhesive onto powder beds. Each method suits different materials (ABS, nylon, aluminum, titanium, ceramics, resins) and tolerances. FDM is fastest and cheapest for prototypes. SLS and metal methods produce stronger production parts but at higher cost and slower speed.

Where it matters in production

3D printing is used to make prototypes before committing to injection molding or casting tooling, which can cost tens of thousands of dollars and take weeks. It is also used to produce low-volume custom parts, dental prosthetics, aerospace brackets, medical implants, and replacement components for older equipment where traditional manufacture is uneconomical. Lead times run from hours to days depending on part size and method. Wall thickness, support structures, post-processing (cleaning, heat treating, surface finishing), and part orientation all affect the final dimensions and surface finish.

The term 'print' is borrowed from 2D inkjet printing but is somewhat misleading: 3D printing is an additive manufacturing process, not printing in the traditional sense. It has become the industry standard verb despite occasional resistance from engineers who prefer 'additive manufacture' or 'rapid prototype'. Accuracy typically ranges from 0.1 mm (SLS, SLA) to 0.5 mm (FDM) depending on machine calibration and material. Anisotropy (layer-to-layer weakness perpendicular to the build direction) is a real concern in structural parts.

Common constraints include part size limits (most machines build within 300 mm x 300 mm x 300 mm), post-processing labor costs, limited material choices compared to traditional manufacturing, and surface roughness that often requires finishing. Support material must be removed or dissolved, adding time and cost. For high-volume production (over 10,000 units), injection molding remains faster and cheaper per unit. 3D printing is most valuable where geometry is complex, customization is needed, or production volume does not justify tooling investment.