Additive manufacturing is the industrial term for 3D printing: building a physical object by adding material layer by layer, guided by a digital design file. Unlike traditional manufacturing, which typically cuts, drills, or mills material away from a solid block, additive manufacturing starts with nothing and deposits only the material needed to form the final shape. The global market hit $20.37 billion in 2023 and is projected to reach $88.28 billion by 2030.
How the Process Works
Every additive manufacturing job starts with a 3D digital model, usually created in CAD (computer-aided design) software. That model gets sliced into hundreds or thousands of thin horizontal cross-sections by a separate program. The printer then builds the object one slice at a time, fusing or depositing material for each layer before moving on to the next.
What that looks like in practice depends on the technology. In powder bed fusion, one of the most common methods for metal parts, a thin layer of metal powder (typically 20 to 200 microns thick) is spread across a build platform. A laser or electron beam traces the shape of that cross-section, melting the powder along its path. The platform then drops down by the thickness of one layer, a fresh coat of powder is rolled out, and the laser traces the next slice. This repeats until the full part is complete. Other processes work differently, using liquid resin cured by light, molten plastic extruded through a nozzle, or droplets of material jetted onto a surface, but the layer-by-layer logic is the same across all of them.
The Seven Process Categories
In 2010, the ASTM standards body classified all additive manufacturing into seven categories. These remain the standard framework for the industry:
- Vat photopolymerization: a light source (laser or projector) cures liquid resin in a tank, layer by layer. Known for high detail and smooth surfaces.
- Material extrusion: melted material is pushed through a nozzle and deposited in lines. This is the technology behind most desktop 3D printers.
- Powder bed fusion: a heat source melts regions of a powder bed. The dominant method for metal parts in aerospace and medical applications.
- Material jetting: droplets of material are deposited and cured, similar to how an inkjet printer works but in three dimensions.
- Binder jetting: a liquid binding agent is selectively deposited onto a powder bed, gluing particles together without melting them.
- Sheet lamination: sheets of material are bonded together and cut to shape.
- Directed energy deposition: material (usually metal wire or powder) is fed into a focused energy beam and melted onto an existing surface. Often used to repair or add features to existing parts.
Materials You Can Print
The material range has expanded well beyond the plastics most people associate with 3D printing. Industrial additive manufacturing now works with metals, polymers, ceramics, composites, biomaterials, and even cementitious materials like concrete. On the polymer side, options range from basic plastics to high-performance engineering thermoplastics used in demanding environments. On the metal side, titanium alloys, stainless steels, nickel superalloys, and aluminum alloys are all routinely printed for end-use parts. The choice of material determines which of the seven process categories you use, since each technology is compatible with only certain material types.
How It Differs From Traditional Manufacturing
Traditional manufacturing is largely subtractive: you start with a block of material and remove everything that isn’t the final part. CNC machining, for example, carves shapes by cutting away metal with spinning tools. This works well but generates significant waste, especially for complex geometries where most of the original block ends up as chips on the floor.
Additive manufacturing flips that equation. Because material is deposited only where it’s needed, AM can reduce material use in final parts by 35 to 80% depending on the geometry. That advantage grows as the part becomes more complex. Research comparing powder bed fusion to CNC milling found that once the ratio of raw material to finished part weight exceeds about 7:1 (meaning the traditional process wastes more than 85% of the starting material), additive manufacturing produces lower environmental impacts across ten different categories, from greenhouse gas emissions to water toxicity.
The tradeoff is speed. For simple shapes produced in high volumes, traditional methods like injection molding or stamping are far faster per unit. Additive manufacturing’s strength lies in low-to-medium production volumes, highly complex geometries, and situations where customization matters more than raw throughput.
Design Freedom
The layer-by-layer approach removes many of the constraints that traditional tooling imposes. You can print internal channels, lattice structures, and organic shapes that no drill bit or mold could create. This enables techniques like topology optimization, where software calculates the most efficient way to distribute material within a given space, often producing bone-like structures that are lighter yet equally strong. These designs frequently look nothing like conventionally manufactured parts, with material only where stress demands it and empty space everywhere else.
One well-known example comes from GE Aviation, which redesigned a fuel nozzle for its LEAP jet engine. What had been an assembly of 20 separate parts became a single printed component. Consolidating parts this way eliminates joints, reduces weight, and removes assembly steps, all made possible because additive manufacturing doesn’t require the part to be moldable or machinable.
Where It’s Used Today
Aerospace was an early adopter because the industry prizes lightweight parts and produces them in relatively low volumes, a sweet spot for additive manufacturing. Fuel nozzles, brackets, and structural components are now routinely printed in flight-grade metal alloys.
Healthcare has become another major sector. The FDA has cleared over 100 medical devices made with additive manufacturing technologies. In roughly a decade, the technology went from a niche process to the preferred manufacturing method for hearing aids and metal spinal implants. The ability to customize each part to a patient’s anatomy, based on their own CT scan data, makes AM especially valuable for orthopedic and dental applications where fit determines outcomes.
Automotive companies use it for prototyping (where 3D printing originally gained traction decades ago) and increasingly for production parts in low-volume or performance vehicles. Consumer goods, energy, and defense industries have all adopted the technology for specific applications where its strengths in complexity, customization, or material efficiency justify the cost.
Post-Processing: What Happens After Printing
A part straight off the printer is rarely ready to use. Most additive manufacturing processes require some degree of finishing work, and for industrial metal parts, that finishing can be substantial.
Support structures come first. Many processes require temporary scaffolding to hold overhanging features in place during the build. These supports, made from the same material or from a dissolvable material, need to be removed mechanically or chemically after printing.
Surface quality is a common issue. Printed parts typically have a rough, slightly porous surface that needs sanding, polishing, or machining to meet specifications. For parts that will experience mechanical stress, heat treatment is often essential. Options include annealing (heating and slowly cooling to reduce internal stresses), hot isostatic pressing (applying high temperature and pressure simultaneously to eliminate internal porosity), and aging treatments that improve strength and dimensional stability. These steps can significantly improve the mechanical performance of printed parts, closing the gap with traditionally manufactured equivalents.
Energy and Environmental Impact
The environmental picture is nuanced. For localized, low-volume production, additive manufacturing can lower energy use by about 25% and greenhouse gas emissions by up to 30% compared to conventional methods. The material savings are real, and printing parts closer to where they’re needed can cut transportation emissions.
But for high-volume production of simple parts, traditional methods like injection molding remain more energy-efficient per unit. The environmental case for additive manufacturing is strongest when the geometry is complex, the production run is short, or the supply chain benefits from decentralized manufacturing. As the technology matures and machines become faster and more energy-efficient, that crossover point is steadily shifting in AM’s favor.