AM

Additive manufacturing (AM) is a family of processes that build solid objects by adding material in successive layers, controlled by digital design files. Unlike traditional subtractive methods that carve away stock, AM deposits or fuses material only where needed, which is why it is also called layer-by-layer manufacturing or 3D printing in casual use.

The most common industrial AM methods include fused deposition modeling (FDM), where thermoplastic filament is melted and extruded; stereolithography (SLA), which hardens resin using ultraviolet light; selective laser sintering (SLS), which fuses powder particles with a laser; and directed energy deposition (DED), which melts powder or wire fed into a melt pool. Metal AM systems typically use powder bed fusion or DED to work with titanium, aluminum, stainless steel, or nickel alloys. Speeds vary widely: FDM systems may take hours for a small part, while industrial powder bed systems can produce larger components in similar timeframes but with higher material costs and tighter tolerances.

Where AM fits in production

AM excels at prototyping, low-volume custom parts, and geometries that are difficult or impossible to machine, such as complex internal channels or lattice structures. Lead times are short because no tooling is required. However, surface finish is often coarse, strength varies by direction (anisotropy), and unit cost rises sharply with volume. For high-quantity production of simple parts, traditional casting or machining remains cheaper and faster. Most manufacturers now treat AM as a complementary process rather than a replacement: rapid tooling, functional prototypes, repair of legacy equipment, and specialized aerospace or medical components are its proven territory.

Material waste is minimal compared to machining, though powder bed systems require careful handling of unused powder for reuse or disposal. Accuracy depends on the process and post-processing: typical tolerances are plusminus 0.1 mm to 0.5 mm for powder bed fusion, wider for FDM. Internal stresses from thermal cycling can cause warping or part failure if design and build parameters are not carefully managed.

The term "additive manufacturing" became standard in the 2000s as patents on early 3D printing processes expired and industrial adoption accelerated. It is preferred in engineering and standards (ISO 52900 and related specifications) because it is process-agnostic and avoids the casual language of "3D printing," which applies to all AM but suggests consumer-grade equipment.