The History of 3D Printing Development, Stage by Stage

• 1
  Where the history of 3D printing development began: photopolymer curing
• 2
  Extrusion and the move to functional plastic parts
• 3
  Metal processes and what they changed for real parts
• 4
  Patents expiring, desktop machines and cheap surface finish
• 5
  Binder jetting, speed and the shift to production volumes
• 6
  How additive and CNC work together now
• 7
  Additive processes compared by what they can hold

The history of 3D printing development starts with one idea: cure a liquid resin point by point, then build the part in layers. Chuck Hull filed the stereolithography patent in 1984 and founded 3D Systems two years later. The first machines used a UV laser on a vat of photopolymer, drawing each cross-section and lowering the build platform by one layer thickness. Layer heights ran around 0.1–0.2 mm, and the early resins were brittle and yellowed under UV light.

The engineering meaning was bigger than the machine. A CAD model could become a physical part without a mold, so designers could hold a shape in their hands before cutting steel. That single change compressed the review loop in product development from weeks to days. It also created the STL format, which is still the default exchange file for most additive systems today.

The limits showed up fast. Photopolymer parts had poor mechanical strength, so they worked as visual models, not functional ones. Support structures had to be cut off by hand. Surface finish on sloped faces carried visible stair-stepping. Those three problems, strength, support removal and stair-stepping, drove almost every later step in the history of 3D printing development.

In the late 1980s Scott Crump developed fused deposition modeling and co-founded Stratasys in 1989. A heated nozzle pushed a thermoplastic filament, usually ABS, onto a moving stage. The process was slower and coarser than SLA, but the parts could be tapped, drilled and snapped into an assembly. That mattered to engineers who needed to test fit, not just look at a shape.

The 1990s added two more processes. Laminated object manufacturing glued and cut sheets of paper or plastic. Selective laser sintering, developed at the University of Texas in the mid-1980s and commercialized by DTM and EOS, fused nylon powder with a laser and produced parts with no support structures at all, because the surrounding powder held the part in place. SLS nylon became the first additive material widely used for functional prototyping and short-run production.

By the end of the 1990s the industry had a working toolkit: resin for fine detail, extrusion for cheap functional parts, powder for strong support-free parts. What it did not have was a way to make metal parts with acceptable density. That gap defines the next phase.

Metal additive manufacturing moved from lab work to production in the 2000s. Laser powder bed fusion, often called DMLS or SLM, spreads a thin layer of metal powder, typically 20–50 μm, and melts the cross-section with a laser. Electron beam systems do the same with a beam in a vacuum and run hotter, which suits titanium and reduces residual stress. Both need support structures and both need stress relief before the part is cut from the build plate.

Density is the number to watch. Well-tuned laser powder bed fusion reaches above 99% relative density in alloys such as Ti-6Al-4V, 316L stainless and Inconel 718. That is close enough to wrought material for many functional parts, but not identical. Build direction changes grain structure, so a part printed vertically can have different fatigue life than the same part printed horizontally.

The practical consequence is that metal printing did not replace machining. It changed which geometry is worth making. Internal channels, lattice structures and merged assemblies became possible. Surfaces that must seal, slide or bear load still get machined afterward. Many production parts today are printed near net shape and then finished on a CNC.

A cluster of early FDM patents expired around 2009. That opened the door to low-cost desktop printers and the open-source community around them. Within a few years a shop could buy an extrusion printer for a few thousand dollars. The trade-off was clear: cheaper hardware, more tuning, and parts with weak layer bonding in the Z direction.

The same decade pushed resin printing down in cost. Digital light processing projectors replaced scanning lasers in some machines, curing a whole layer at once. Layer heights dropped to 0.025–0.05 mm, and desktop resin printers began producing small parts with smooth surfaces and fine features. Dental models, hearing aid shells and investment casting patterns moved to these machines in volume.

For an engineer, the lesson from this stage is that process choice follows feature size and material, not price alone. A cheap desktop machine can hold a 0.1 mm feature on a 20 mm part. It cannot hold a 0.05 mm tolerance across a 300 mm part. That distinction still decides most quoting conversations.

Binder jetting, developed at MIT in the early 1990s and later commercialized for metal, deposits a liquid binder into a powder bed instead of melting it. The green part is then sintered in a furnace. Because a print head covers a wide area per pass, the process is much faster per part than laser melting, and parts are supported by the powder bed, so support removal is simpler.

Sintering shrinks the part, typically by 15–20% in linear dimension depending on alloy and powder. That shrink is predictable and compensated in the CAD model, but it makes tight tolerances harder to hold than in a machined part. As-sintered surfaces are rough, often around Ra 6–10 μm, so sealing faces and bearing bores get machined after sintering.

This is where additive stopped being only a prototyping story. Binder jetting made it economic to run hundreds or thousands of small metal parts per build, which is why it appears in production planning for brackets, manifolds and heat sinks. The machining step after sintering is what brings those parts into tolerance.

Modern production rarely uses one process alone. A typical workflow prints a near-net shape, then machines the critical features. The printed blank saves material and tool wear on complex internal geometry. The CNC step delivers the tolerances that matter: ±0.005 mm on a bearing bore, Ra 0.8–1.6 μm on a sealing face, a flat mounting surface within 0.02 mm.

At GreatLight we run both sides of that workflow. Additive covers custom 3D printing and rapid prototyping, including metal and engineering plastic parts. Subtractive covers 5-axis, 4-axis and 3-axis machining, mill-turn work and finishing. Parts up to 4,000 mm can be handled on the machining side, and one-off prototypes sit alongside 10,000+ part runs with no minimum order quantity.

The judgment call is usually about geometry, not cost. If a part has deep internal channels, merged sub-assemblies or a lattice that would be slow to cut, print it. If it has tight bores, threads, sealing faces or a flatness callout under 0.05 mm, machine it, or print it and machine the critical faces. Choosing wrong in either direction adds cost and time.