CourseWiki/Materials and Manufacturing Processes/Foundations

Additive Manufacturing Process Families

Identify an additive process by what it places, what joins the material, and what the part still needs after the build.

Classify the mechanism before comparing process names

Additive manufacturing builds three-dimensional geometry by adding material. The standard process families describe how material is placed and joined. They are different from this course's five purpose categories, which describe what an operation is intended to accomplish.

Use three questions when you meet an unfamiliar name: What feedstock enters? What places or selects each region? What joins or solidifies it? Then ask what must happen after the build before the part is ready to inspect or use.

For the course's purpose model, additive shape-building is primarily Forming. Removing supports is a later Separating operation; curing or heat treatment can be Conditioning; finishing can change a surface. The seven AM families below do not replace those five purpose categories.

Vocabulary, brand attribution and source scope

ISO/ASTM 52900:2021 is the current fundamentals-and-vocabulary standard and describes additive shaping as successive addition of material. Its public abstract does not reproduce the full family list. The family structure and readable mechanisms here are checked against the NIST AM technology overview and the seven-family discussion in ORNL's Additive Manufacturing Design Guidelines. Stratasys's legal terms identify FDM as a registered trademark and PolyJet as a trademark; its PolyJet technology page documents the bounded photopolymer-droplet, UV-cure and support example used here. This page paraphrases sources and uses original graphics rather than copied standard or vendor art.

Seven families place and join material in different ways

Family	Feedstock and joining mechanism	A useful boundary
Material extrusion	Material is pushed through a nozzle and selectively deposited. A common filament route softens thermoplastic, then adjacent roads bond as they cool.	FDM is a registered trademark of Stratasys; FFF is generic usage for filament fabrication. Neither name covers every extrusion feedstock.
Vat photopolymerization	Light selectively cures liquid photopolymer held in a vat. SLA, DLP and masked exposure systems select regions differently.	Cleaning, support removal and material-specific post-curing may remain. “Resin printing” does not identify one universal exposure method.
Powder bed fusion	A thin powder layer is spread, then thermal energy selectively fuses regions. Polymer SLS uses a laser; HP Multi Jet Fusion applies agents and heat. Metal routes use laser or electron-beam energy.	Polymer and metal PBF share a family, not one identical workflow. Loose powder can support polymer SLS parts, while some metal routes need supports for anchoring or heat flow; process-specific exceptions exist.
Binder jetting	A printhead selectively deposits binder into a powder layer. Repeating the powder-and-binder cycle produces a fragile green shape.	The printed shape is not automatically a finished dense part. Curing, depowdering, debinding, sintering or infiltration depend on the material and route.
Material jetting	Droplets containing build material are selectively deposited, then solidified or cured. PolyJet is a Stratasys photopolymer-and-UV example.	The jetted liquid is build material, not merely binder placed into a powder bed. PolyJet is one branded implementation, not the family name.
Directed energy deposition	Powder or wire is delivered to a target while focused energy creates a local melt zone. Deposited tracks solidify on a substrate or existing part.	The feed arrives at the deposition point rather than being spread as a complete powder layer. Repair and large features are useful contexts; finishing and inspection still matter.
Sheet lamination	Sheets are bonded to build thickness, with shape developed layer by layer.	The family name alone does not establish the sheet material, bonding method, accuracy or present-day machine capability.

Material names do not move freely between families. A printer, process version and qualified feedstock must be considered together. Polymer, metal, ceramic, composite, sand and cementitious examples exist in particular systems; that does not mean every material works in every printer.

Powder and droplets can play three different roles

Three original process sequences. Powder bed fusion spreads powder and uses energy to fuse selected regions. Binder jetting spreads powder and deposits binder to make a green part that may need later consolidation. Material jetting deposits droplets that contain the build material and then solidifies them. — Similar words do not mean the same mechanism. Follow what the droplets contain and when the material becomes the intended solid.

Powder bed fusion: The powder is the build material; selected regions are thermally fused during the build.
Binder jetting: The powder is the build material; jetted binder holds a green shape that may require later densification.
Material jetting: The droplets themselves contain build material; a separate support material may also be deposited in some systems.

HP Multi Jet Fusion belongs with powder bed fusion because agents help control where powder is fused by heat. It is not binder jetting simply because a printhead deposits an agent. See the manufacturer's mechanism comparison for that distinction.

The build is one stage of the manufacturing route; Checklist; Practice

The build is one stage of the manufacturing route

Judge a route from feedstock through the inspected part, not from the printer alone. Depending on the family and material, the route may include cooling, unpacking and depowdering; washing and post-curing; support removal; debinding and sintering; heat treatment; machining; surface finishing; or inspection.

State the material, required geometry, load direction, critical surfaces and fit.
Identify what carries an overhang during the build and whether that material can be removed afterward.
Trace trapped powder, uncured resin, support material or internal passages to an exit or cleanup method.
Name the state at the end of the machine cycle: finished solid, green part, supported part, powder-filled part or another intermediate state.
List the post-build and inspection steps required before the part can meet its intended requirement.

No family is the universal best choice. Surface, accuracy, properties, cost and throughput depend on the actual material-process-machine combination, build use, postprocessing and acceptance requirements. Continue to FDM 3D Printing for the material-extrusion mechanism and 3D Printing from CAD for the filament CAD-to-slicer workflow.

Identify material extrusion Distinguish fusion from binder Follow a green part

Appears in

Additive Manufacturing DET 102 DET 130 DET