ENG201 Module A: Design for Additive Manufacturing

Vocabulary flashcards covering the fundamentals, processes, and design considerations for Additive Manufacturing based on ENG201 Module A.

Additive Manufacturing

The process of converting a $3D$ design to a physical part through layer-based deposition (or addition) of materials.

Subtractive Manufacturing

A manufacturing process, such as machining, where material is removed from a material bulk.

Dr. Hideo Kodama

The Japanese researcher who filed the first Additive Manufacturing patent in $1980$ using photopolymer material and light.

Chuck Hull

The co-founder of $3D$ Systems who invented stereolithography ($SLA$) in $1986$, considered the first rapid prototyping system.

Vat Photopolymerization

An $AM$ process where liquid photopolymer in a vat is selectively cured by light-activated polymerization (crosslinking).

Powder Bed Fusion

An $AM$ process where thermal energy (laser or $EB$) selectively fuses regions of a powder bed.

Material Extrusion

An $AM$ process where material is selectively dispensed through a nozzle or orifice, typically involving heated filament pushed by pinch rollers.

Material Jetting

An $AM$ process where droplets of build material are selectively deposited.

Binder Jetting

An $AM$ process where a liquid bonding agent is selectively deposited to join powder materials.

Sheet Lamination

An $AM$ process where sheets of material are bonded to form an object.

Directed Energy Deposition

An $AM$ process where focused thermal energy is used to fuse materials by melting as the material is being deposited.

STL (STereoLithography)

A file format that approximates CAD model surfaces with triangle vertices and surface normal vectors; it contains no units, color, or material information.

AMF (Additive Manufacturing File)

The official $ASTM$ Committee $F42/ISO$ standard file format which includes curved triangles, dimensions, color, texture, and multiple materials.

Slicing Software

Software used to reposition, reorient, rescale, and determine layer height and infill density of a model before transferring the job to an $AM$ machine.

PLA (Polylactic Acid)

An $FDM$ material that is easy to print, biodegradable, and has low warping, but is brittle with low heat resistance.

ABS (Acrylonitrile Butadiene Styrene)

A strong, impact-resistant, and heat-resistant $FDM$ material that warps easily and emits fumes during printing.

Shell/Perimeter

The number of outer walls printed for each layer, which influences the strength and surface quality of the part.

Infill Density

A parameter that provides internal support and strength to the printed object by controlling the amount of material inside the shells.

Layer Height

The height of each printed layer, typically ranging from $0.1\,mm$ to $0.3\,mm$; lower heights result in better resolution but longer print times.

Skirt

A border around the $3D$ printed object that does not touch the part, used to prepare the nozzle and check calibration.

Brim

A connected border extending from the edges of a printed part to improve bed adhesion and minimize warping.

Raft

A printed platform on which parts are built to improve adhesion and ensure a level surface, though it can leave a rougher surface on the bottom layer.

Anisotropy

The phenomenon where printed parts are weaker along the $Z$-axis due to layer delamination.

Photopolymerization

The chemical reaction (crosslinking) where liquid monomers link into polymers and become solid when exposed to radiation.

Photo initiators

Compounds within liquid monomers that become reactive when exposed to light, starting a polymer chain.

IPA (Isopropyl alcohol)

A solvent used in $SLA$ post-processing to rinse uncured resin from the surface of the printed part.

Drain Holes

Feature added to hollow models in $SLA$ to allow uncured resin to escape and avoid suction issues.

Vector scan

A point-wise approach to Vat Photopolymerization typical of commercial $SLA$ machines.

Mask projection

A layer-wise approach to Vat Photopolymerization that exposes entire layers at one time, typically using a Digital Micromirror Device ($DMD$).

Post-Curing

The final step in $SLA$ where parts are placed in a $UV$ chamber for $10-30$ minutes to fully cure the resin and improve mechanical strength.