Additive Manufacturing Methods and Materials 141

3D

Three-dimensional. Having a length, depth, and width. 3D parts are created by additive manufacturing methods.

acrylates

A thermoset polymer that is transparent, elastic, and highly fracture resistant. Acrylates are common thermosets that are used as build materials in additive manufacturing.

acrylonitrile butadiene styrene

ABS. A thermoplastic material with good heat, chemical, and impact resistance. Acrylonitrile butadiene styrene is a common polymer that is used as build material in additive manufacturing.

additive manufacturing

AM. The process of joining or solidifying materials to make an object based on a three-dimensional computer model. Additive manufacturing methods typically build up layers of material to create an object.

adhesive

A substance used to join two or more materials. Adhesives have a wide range of properties that make them suitable for a variety of manufacturing applications.

aerospace

The industry that covers machines or vehicles of flight. Aerospace manufacturers generally require workpiece materials with very specific properties.

alloys

A uniform mixture of two or more materials, one of which must be a metal. Alloys include stainless steel, bronze, and various superalloys.

aluminum

A silver-white, lightweight metal that resists corrosion and is a good conductor of electrical and thermal energy. Aluminum is sometimes used as build material in additive manufacturing.

AM

Additive manufacturing. The process of joining or solidifying materials to make an object based on a three-dimensional computer model. AM methods typically build up layers of material to create an object.

ambient-temperature

The temperature of the air and surrounding environment. Ambient-temperature processes include ultrasonic consolidation (UC), which is performed by open-air systems.

atomization process

A group of processes that creates powder by breaking up a liquid into very fine droplets. Atomization processes include water atomization and gas atomization.

axes

An imaginary straight line or circle used to describe the location or movement of an object in three-dimensional space. Axes can be either vertical or horizontal.

binder

An adhesive material that holds together other materials. Binders hold together powdered materials to make a solid part in binder jetting.

binder jetting

An additive manufacturing method in which liquid binder is used to join powdered materials to create a part. Binder jetting can use a variety of powdered build materials, including polymer, metal, and sand.

biomaterials

A natural material that composes a part or all of a living structure. Biomaterials, like living cells and tissues, can be used in some additive manufacturing methods.

bonds

To hold together by a force of attraction or by the application of heat, pressure, or an adhesive. Some additive manufacturing methods, such as binder jetting and sheet lamination, bond materials together to build a part.

bottom-up printing

A vat photopolymerization system orientation in which the light source is beneath the vat and the build platform is above the vat. Bottom-up printing systems project light upward into the vat to cure and create a part layer, while the build platform moves upward to slowly draw a part out of the vat as each layer completes.

break-away support systems

BASS. An additive manufacturing support material that can be removed from the build by hand. Break-away support systems are used in material extrusion.

bronze

Any copper-based alloy that does not use zinc or nickel as the primary alloying element. Bronzes, which commonly contain tin, aluminum, or silicon, can be powdered and used as build material in additive manufacturing.

build area

The location and space within an additive manufacturing machine in which the part is actually constructed. Build areas in some additive manufacturing machines are open while others are surrounded by an enclosure.

build lines

The visible boundaries between layers of hardened material that compose an additively manufactured part. Build lines can be prone to fatigue failure.

build material

The substance used to create a part in additive manufacturing. Build materials include types of metals, polymers, composites, and ceramics.

build parameters

An adjustable variable that controls an aspect of an additive manufacturing process. Build parameters for powder bed fusion (PBF) include bed temperature, electron or laser beam intensity, and layer thickness.

build platform

The flat surface on which a part is additively manufactured. The build platform can either be a permanent machine surface from which parts are removed or a surface that can be removed from a machine once the build is complete.

build rates

The time it takes to build a part or the number of parts that can be made in a set period of time. Build rates, or production rates, for additive manufacturing are considerably lower than traditional manufacturing.

cells

The basic structural unit that makes up almost all living organisms. Cells can be used as build materials in some specialized material extrusion systems.

ceramics

A group of inorganic materials that consists of both metallic and nonmetallic atoms held together by a strong primary bond. Ceramics, which include metal oxides, nitrides, and glasses, are sometimes used as build material in additive manufacturing.

chemical bath

A specialized solution that helps remove support material from some additively manufactured parts. Chemical baths are formulated to dissolve support materials without harming the part.

chemical reaction

A process in which one or more substances are changed into another substance or substances. Chemical reactions alter the physical structure of a substance in some way.

coating

A finishing process that applies a protective film to the surface of an object to improve its functionality. Coating helps improve a part's ability to withstand environmental hazards, such as extreme heat or flying debris.

cobalt chrome

A superalloy containing larger amounts cobalt and chromium along with lesser amounts of other alloying elements. Cobalt chrome is sometimes used as build material in additive manufacturing.

composites

A group of materials that are made by mixing together two or more of the following groups: metals, plastics, and ceramics. Composite materials are sometimes used as build material in additive manufacturing.

contours

A curved surface or feature of a workpiece. Contours are cut into successive layers of build material during sheet lamination.

copper

A reddish nonferrous metal that is very ductile. Copper is thermally and electrically conductive as well as corrosion resistant.

cores

A solid component placed inside a mold cavity that forms the hollow part or internal feature of a casting. Cores with exceptional accuracy can be created using binder jetting and other additive manufacturing methods.

cure

To cause a material to bond and solidify by permanently cross-linking its molecules through heat, light, time, or chemical means. Build materials may cure when they are exposed to ultraviolet light or when they cool and solidify.

dead zone

A very thin area of photopolymer materials held in a vat in which photopolymerization cannot occur due to the presence of oxygen. Dead zones prevent liquid photopolymer from curing and adhering to the optical window of vat photopolymerization systems that are oriented for bottom-up printing.

DED

Directed energy deposition. An additive manufacturing method in which focused thermal energy is used to melt materials as they are deposited on a build platform. DED is often used with metal powder or wire.

defects

An imperfection in a part that prevents it from operating correctly. Defects sometimes appear in additively manufactured parts when layers do not adhere to each other correctly or when surface porosity occurs in a part.

density

The amount of mass within a specific volume. Objects with greater density have increased mass and weight.

deposition head

A nozzle that melts and dispenses material. Deposition heads are used in directed energy deposition (DED) processes, such as electron beam AM (EBAM) and laser-engineered net shaping (LENS).

deposition rates

The rate at which material is layered in an additive manufacturing process. Deposition rate helps determine the speed at which a part is built.

diameter

The distance from one edge of a circle to the opposite edge that passes through the center. The diameter of an extrusion head determines the material layer thickness.

digital light processing

DLP. A vat photopolymerization process that uses a specialized projector to display an entire image onto a layer of photopolymer at one time. Digital light processing is a faster process than stereolithography (SLA).

direct metal deposition

DMD. A directed energy deposition process that uses a laser or plasma arc to melt build materials as they are deposited on a build platform. Direct metal deposition most frequently uses metal powders as build materials.

direct metal laser sintering

DMLS. A powder bed fusion (PBF) process that builds a part using a laser to heat and fuse together successive layers of powdered metal. Direct metal laser sintering can produce complex metal parts.

directed energy deposition

DED. An additive manufacturing method in which focused thermal energy is used to melt materials as they are deposited on a build platform. Directed energy deposition is often used with metal powder or wire.

distort

To change from a natural shape and condition. Parts may distort due to thermal stress produced during some additive manufacturing methods.

DMLS

Direct metal laser sintering. A powder bed fusion (PBF) process that builds a part using a laser to heat and fuse together successive layers of powdered metal. DMLS can produce complex metal parts.

drilling

A traditional machining operation that creates a new round hole into a workpiece surface using a multi-point tool. Drilling is sometimes used during the ultrasonic consolidation process to create internal channels, and it is sometimes required during the post-processing of parts created by sheet lamination.

drive roll

A set of wheels that feed a filament of build material through an extrusion head and to the nozzle of a material extrusion system. Drive rolls are specially designed for various types and sizes of build material filaments

EBM

Electron beam melting. A powder bed fusion (PBF) process that builds a part using an electron beam to liquefy and fuse together successive layers of powdered metal. EBM is more expensive than other PBF processes but produces parts with superior physical and mechanical properties.

efficiency

A measure of the energy output of a system or process versus the total energy supplied to it. The efficiency of some additive manufacturing methods, such as material extrusion, is often affected by the level of resolution and complexity that a final part requires.

electron beam

A narrow stream of focused electrons that create thermal energy. Electron beams are sometimes used in additive manufacturing methods, including directed energy deposition (DED) and powder bed fusion (PBF).

electron beam additive manufacturing

EBAM. A directed energy deposition process that uses an electron beam to melt materials as they are deposited on a build platform. Electron beam additive manufacturing can use either wire or powder feedstock as build materials.

electron beam melting

EBM. A powder bed fusion (PBF) process that builds a part using an electron beam to liquefy and fuse together successive layers of powdered metal. Electron beam melting is more expensive than other PBF processes but produces parts with superior physical and mechanical properties.

embedded

To be enveloped by or surrounded by another material or object. Parts with embedded electrical components can be built using ultrasonic consolidation (UC).

enclosure

A physical barrier designed to protect the build area and prevent materials from exiting the build area. Enclosures for directed energy deposition systems sometimes include shielding gas.

end-use

Designed to be used directly by a consumer or directly in another manufactured product. End-use products created by additive manufacturing include medical implants, custom dental devices, and camera equipment.

extruding

To force a material, usually a polymer, through a nozzle or a die. Some additive manufacturing methods build a product by extruding material onto a platform.

extrusion head

A nozzle or die that shapes and dispenses semi-solid material. Extrusion heads are used in some additive manufacturing methods, such as material extrusion.

features

A distinguishing characteristic that performs a function on a part. Features include grooves, shoulders, and hinges, among many others.

feedstock

Raw material that is used to make manufactured parts. Feedstock for additive manufacturing methods includes filaments, pellets, wire, and powder.

filaments

An extremely thin strand of material. Filaments of thermoplastic material are sometimes used in material extrusion as build material.

finishing processes

The treatment of a surface to remove roughness and irregularities and improve its appearance. Finishing processes include sanding, heat treating, and painting.

flash cures

To cause a material to bond and solidify by exposing it to a flash of ultraviolet (UV) light. Material jetting systems use an ultraviolet lamp to flash cure build materials as they are deposited on to a build platform.

foil

An exceedingly thin sheet of metal. Foils are usually made with metals, such as aluminum, copper, or tin, that are easily stretched or drawn out.

foundry sand

A material consisting of sand mixed with additives, such as clay, coal, and water. Foundry sand, or green sand, can be used in binder jetting machines to build molds for use in sand casting processes.

frequencies

The number of sound wave oscillations or vibrations in a unit of time as measured in hertz (Hz). Frequencies that are higher involve more wave cycles than low frequencies in the same amount of time.

fuse

To blend with other materials to form a single object. Additive manufacturing methods, such as directed energy deposition (DED) and powder bed fusion (PBF), often fuse materials together to form a final product.

fused deposition modeling

FDM. An additive manufacturing method that uses a nozzle to dispense material, usually a thermoplastic filament, onto a build platform. Fused deposition modeling is sometimes referred to as either material extrusion or fused filament fabrication (FFF).

fused filament fabrication

FFF. An additive manufacturing method that uses a nozzle to dispense material, usually a thermoplastic filament, onto a build platform. Fused filament fabrication is sometimes referred to as either material extrusion or fused deposition modeling (FDM).

gas atomization

An atomization process that creates powder by breaking up liquid into droplets using a high-pressure inert gas. Gas atomization produces powder particles that are uniform in both shape and size.

geometric complexity

The linear and curved shapes that characterize a part. Geometric complexity is one of the key advantages of additive manufacturing.

gradation

Containing a series of changes in material composition. Gradation allows a part to have different materials, properties, or colors at different places.

green

A weak part made from powdered materials bound with adhesive into its final shape. Green parts are extremely fragile and must undergo various post-processing steps to harden them before use.

grinding

A subtractive manufacturing process used to improve surface finish and bring parts into close tolerance. Grinding operations typically remove small amounts of workpiece material using abrasive wheels.

heat resistant

Able to withstand high temperatures. Heat resistant parts will not deform or lose their shape when exposed to heat.

heat treatment

A controlled heating and cooling process used to change the structure of a material and alter its physical and mechanical properties. Heat treatments are sometimes used to improve the properties of additively manufactured parts.

heating element

A device that heats a component when activated. Heating elements melt build materials before a nozzle extrudes them onto a build platform during material extrusion.

hertz

Hz. A unit of frequency equal to one cycle per second. Hertz can measure the frequency of sound waves or electromagnetic radiation.

homogenous

Uniform in composition and properties. Homogenous part layers are achieved by powder bed fusion (PBF) processes, such as selective laser melting (SLM) or electron beam melting (EBM), which fully melt, rather than sinter, build materials.

horizontally

Parallel to the horizon or ground. Extrusion heads usually move horizontally, from side to side or left to right, to dispense layers of build material.

hot isostatic pressing

HIP. A traditional manufacturing process that simultaneously subjects a part to high heat and gas pressure. Hot isostatic pressing can be used to decrease an additively manufactured part's porosity and increase its density.

hybrid process

A process that uses both traditional and additive manufacturing to create a finished part. Hybrid processes can involve either using a traditional manufacturing process on a mostly additively manufactured part or vice versa.

image projection module

An assembly of components that focuses and directs the movement of a laser or electron beam in a specific pattern. Image projection modules are used during powder bed fusion (PBF) and vat photopolymerization processes.

implants

An object that is inserted within an individual's body, usually through surgery. Implants must be made of materials that are biocompatible and will not cause a negative reaction within the body.

impurity content

The degree to which a material contains foreign elements or substances. The impurity content of a metal powder depends on its atomization process.

Inconel

A superalloy based in nickel and chromium that is designed to perform well in extreme environments. Inconel resists both oxidation and corrosion.

inert

A gas that does not chemically react with the substance it contacts. Inert gases include nitrogen, helium, and argon.

infiltration

The process of a substance entering a porous material in order to fill any empty spaces or voids. Infiltration is a specialized post-processing step that is sometimes used to harden and strengthen parts produced by binder jetting.

infrared

IR. An area outside of the visible part of the color spectrum, beyond red. Infrared lasers are often used as thermal energy sources in some powder bed fusion (PBF) processes, such as selective laser sintering (SLS) and direct metal laser sintering (DMLS).

intensity

A measurement that describes the strength of energy being transmitted during a process. The intensity of the thermal energy used during some additive manufacturing methods, such as powder bed fusion (PBF), must be carefully regulated.

internal channels

A pathway for air, coolants, or other substances to travel through the inside of a part. Internal channels are most easily created through additive manufacturing processes.

laminated object manufacturing

LOM. A sheet lamination process that uses an adhesive to bond successive layers of material together to build a final part. Laminated object manufacturing most frequently uses paper as build material but can also use thermoplastic and composite sheets.

laser

An intense beam of light that can be precisely aimed and controlled. Lasers are sometimes used to selectively solidify or combine materials in additive manufacturing methods, including directed energy deposition (DED), powder bed fusion (PBF), and vat photopolymerization.

laser-engineered net shaping

LENS. A directed energy deposition process that uses a laser beam to melt materials as they are deposited on a build platform. Laser-engineered net shaping is sometimes referred to as laser powder forming.

LENS

Laser-engineered net shaping. A directed energy deposition process that uses a laser beam to melt materials as they are deposited on a build platform. LENS is sometimes referred to as laser powder forming.

light source

A device that emits a beam or beams of light. Light sources for vat photopolymerization processes include lasers, electron beams, light-emitting diodes (LEDs), X-rays, and xenon arc lamps.

light-activated polymerization

A chemical reaction that causes the molecules of photopolymer materials to bond together when exposed to light. Light-activated polymerization is used in vat photopolymerization.

light-emitting diodes

LEDs. A semiconductor device that emits a narrow spectrum of light in a forward direction. Light-emitting diodes are sometimes used as light sources in vat photopolymerization.

liquid

A state of matter that is cohesive and has the ability to flow. Liquids are the room temperature forms of some substances, such as water, or the melted form of others, such as metals.

LOM

Laminated object manufacturing. A sheet lamination process that uses an adhesive to bond successive layers of material together to build a final part. LOM most frequently uses paper as build material but can also use thermoplastic and composite sheets.

machining

A subtractive manufacturing process that involves removing material to form an object. Machining includes methods such as milling, turning, and drilling that remove metal using cutting tools.

material extrusion

An additive manufacturing method that uses a nozzle to dispense material, usually a thermoplastic filament, onto a build platform. Material extrusion is sometimes referred to as either fused deposition modeling (FDM) or fused filament fabrication (FFF).

material jetting

An additive manufacturing method in which droplets of build material are selectively deposited onto a build platform. Material jetting, or multi-jet modeling (MJM), uses ultraviolet (UV) light to cure photopolymer build material.

mechanical properties

The collection of characteristics that describe a material's ability to compress, stretch, bend, scratch, dent, or break. Mechanical properties of a material are determined by its molecular structure.

melt pool

The small area of molten material that forms during directed energy deposition. Melt pools form a permanent material layer when they cool.

melting point

The temperature at which a material changes from a solid to a liquid. Melting points vary based on the material's microstructure.

metal-matrix composites

MMC. A composite made from a metallic matrix and high-performance reinforcement materials. Metal-matrix composites have high levels of strength, stiffness, and relatively high resistance to heat.

metals

A naturally occurring material group that consists of tightly packed atoms held together by a strong primary bond. Metals include copper, iron, nickel, and lead.

microstructure

The shape and alignment of microscopic components in a material. Microstructure helps determine the properties of a material.

mill

A multi-point cutting tool that is used to remove metal from the surface of a workpiece. Mills are used to cut a sheet of metal foil to the near net-shape of a final part during ultrasonic consolidation (UC).

milling

A traditional machining operation that uses a multi-point horizontal or vertical cutter to remove metal from the surface of a workpiece. Milling is used during the ultrasonic consolidation process to cut sheets of metal foil to the near-net shape of a final part, and it is sometimes required during the post-processing of parts created by sheet lamination.

molds

A hollow cavity that holds heated liquid metal and imparts its shape on the metal as it cools. Molds with exceptional accuracy can be created using binder jetting and other additive manufacturing methods.

molecules

A group of atoms held together by either primary or secondary bonds. Molecules are the smallest unit into which a material can be divided without changing its properties.

motion system

A directed energy deposition machine configuration that determines the type of movement a machine is capable of making. Motion systems include machines that move only a workpiece, only a deposition head, or both a workpiece and deposition head.

multi-jet modeling

MJM. An additive manufacturing method in which droplets of build material are selectively deposited onto a build platform. Multi-jet modeling, or material jetting, uses ultraviolet (UV) light to cure photopolymer build material.

near net-shape

A part that is close to meeting consumer or manufacturer specifications, including tolerance and surface finish, directly after it is manufactured. Near net-shape parts can be produced by ultrasonic consolidation (UC).

negative spaces

An empty area either surrounding a part, contained within a part, or lying between features of a part. Negative spaces are sometimes created using support material in additive manufacturing methods.

nickel-based superalloys

A superalloy containing larger amounts of nickel along with various, lesser amounts of other alloying elements. Nickel-based superalloys are common superalloys used in additive manufacturing processes.

nonhomogenous

Having a composition and properties that vary and are not uniform. Nonhomogenous parts have limited functionality and reduced applications compared to homogeneous parts.

nozzle

A spout at the end of piping or tubing through which substances are funneled. Nozzles are used to distribute build material during material extrusion.

operators

A person trained to run a specific machine. Operators are responsible for ensuring that a machining process runs properly, efficiently, and safely.

optical properties

A set of characteristics that describe the physical appearance of an object. Optical properties include a material's transparency, opacity, and color.

optical window

The transparent floor of the vat that holds liquid photopolymers in vat photopolymerization systems oriented for bottom-up printing. The optical window allows light to pass through and contact the photopolymer material.

overhangs

A section or feature on a part that extends outward and past the base. Overhangs are often created using support material in material extrusion.

oxidizing

Combining with or chemically reacting to oxygen. Oxidizing can be prevented by using shielding gases during directed energy deposition (DED) processes.

oxygen

A colorless, odorless, tasteless gas that naturally exists in the atmosphere. Oxygen inhibits the light-activated polymerization process.

oxygen-permeable

An object or surface that allows oxygen to pass through it. Oxygen-permeable optical windows are used in vat photopolymerization systems that are oriented for bottom-up printing.

PA

Polyamide. A semicrystalline thermoplastic that gains strength when the fibers are stretched. PA is a common polymer that is used as build material in additive manufacturing.

PBF

Powder bed fusion. An additive manufacturing method that uses thermal energy to either sinter or melt together layers of powdered polymer, metal, ceramic, or other material. PBF processes often use either lasers or electron beams as thermal energy sources.

PC

Polycarbonate. A type of thermoplastic that is used for items that require high heat resistance. PC is a common polymer that is used as build material in additive manufacturing.

pellets

A very small, round ball of material. Pellets of thermoplastic material are sometimes used in material extrusion as build material.

photopolymers

A thermoset polymer that cures and hardens when exposed to light. Photopolymers are used in material jetting and vat photopolymerization systems.

physical properties

A set of characteristics that describes how a material responds to environmental, thermal, electrical, and magnetic forces. Physical properties describe how a material reacts to forces other than mechanical forces.

plasma arc

A stream of plasma formed by an electrode ionizing air or another gas and heating it to a high temperature. Plasma arcs are sometimes used in additive manufacturing methods, including directed energy deposition (DED).

polyamide

PA. A semicrystalline thermoplastic that gains strength when the fibers stretch. Polyamide is a common polymer that is used as build material in additive manufacturing.

polycarbonate

PC. A type of thermoplastic that is used for items that require high heat resistance. Polycarbonate is a common polymer that is used as build material in additive manufacturing.

polylactic acid

PLA. A biodegradable thermoplastic in the polyester family. Polylactic acid is a natural polymer derived from corn starch and other renewable resources.

polymers

A natural or synthetic material group that consists of very large molecules held together by either a secondary bond or a primary bond. Polymers include silk, nylon, rayon, and plastics.

post-processing

A group of procedures that are used to clean, improve, or otherwise finish a part for use by a manufacturer or consumer. Post-processing for additively manufactured parts includes abrasive finishing, heat treatment, and painting.

powder bed

The area of a powder-based additive manufacturing machine that holds granulated build material and provides the build platform. Powder beds are used in binder jetting and powder bed fusion (PBF).

powder bed fusion

PBF. An additive manufacturing method that uses thermal energy to either sinter or melt together layers of powdered polymer, metal, ceramic, or other material. Powder bed fusion processes often use either lasers or electron beams as thermal energy sources.

pressure

A force or stress that, when applied, causes changes to the properties of the material. Pressure is sometimes applied to layers of build material in order to bond them together during binder jetting and sheet lamination.

print heads

The moving component on a printer that holds and distributes the part build material. Additive manufacturing machines, such as material jetting or binder jetting, have print heads.

production rates

The time it takes to build a part or the number of parts that can be made in a set period of time. Production rates, or build rates, for additive manufacturing are considerably lower than traditional manufacturing.

projector

A device that creates a two-dimensional layer of light. Projectors are used by some vat photopolymerization systems to create an entire part layer in a single moment.

proprietary

Designed by a specific company for use only with its own systems. Vat photopolymerization includes some proprietary processes that may differ slightly from stereolithography (SLA) and digital-light processing (DLP).

prototypes

A preliminary model of a product used to evaluate the performance of a design. Prototypes provide a design basis for final products.

radiation

Energy emitted from either invisible or visible wavelengths of light. Radiation is used to cure photopolymer build materials during vat photopolymerization.

recoater

A device that slides forwards and backwards over top the surface of photopolymer material held in a vat. Recoaters are used by stereolithography (SLA) systems to smooth photopolymer material layers over top a build platform.

resolution

The fineness of detail in the computer-generated model used in additive manufacturing. Resolution helps determine the surface finish quality of an additively manufactured part, with greater resolution leading to better surface finish.

robotic arm

A programmable or remote-controlled device that simulates the movement of a human arm. Robotic arms are used in a variety of assembly and manufacturing applications.

roller

A cylindrical device that rotates forwards and backwards to move a load. Rollers are used by binder jetting, powder bed fusion, and sheet lamination systems to move and position build materials over top a build platform.

sand casting

The process of making a part by pouring molten metal into a sand mold. Sand casting uses disposable molds that can be made by binder jetting and other additive manufacturing methods.

sanding

A type of grinding process that uses a fine-grain abrasive to remove small amounts of surface material. Sanding can be used to improve the surface finish of some additively manufactured parts.

SDL

Selective deposition lamination. A sheet lamination process that applies heat and pressure to bond successive layers of material together to build a final part. SDL most frequently uses paper as build material but can also use thermoplastic and composite sheets.

sealing

The process of applying an impermeable, nonporous coating to a part. Sealing can improve the porosity of parts produced by selective laser sintering (SLS) and direct metal laser sintering (DMLS).

seals

To fill in any voids in a part's surface to make it impermeable. Parts produced by binder jetting undergo an infiltration post-processing step that seals their surfaces.

selective deposition lamination

SDL. A sheet lamination process that applies heat and pressure to bond successive layers of material together to build a final part. Selective deposition lamination most frequently uses paper as build material but can also use thermoplastic and composite sheets.

selective laser melting

SLM. A powder bed fusion (PBF) process that builds a part using a laser to melt together successive layers of powdered metals. Selective laser melting is similar to selective laser sintering (SLS) but produces stronger and denser parts by fully melting build materials.

selective laser sintering

SLS. A powder bed fusion (PBF) process that builds a part using a laser to successively sinter and fuse layers of powdered material, usually polymers or ceramics. Selective laser sintering can produce complex, detailed parts.

sensors

A device that detects the presence or absence of an object, or certain properties of that object, and provides feedback. Sensors send feedback in the form of signals, which can be measured and recorded.

sheet lamination

An additive manufacturing method that forms an object by bonding sheets of material together using an adhesive, heat, or pressure. Sheet lamination processes include selective deposition lamination (SDL), laminated object manufacturing (LOM), and ultrasonic consolidation (UC) or ultrasonic additive manufacturing (UAM).

shielding gas

A gas that protects a material or process from atmospheric contamination. Shielding gases include nitrogen and compressed air and are selected based on the job specifications.

single-point source

An additive manufacturing (AM) device that layers, sinters, or cures a part layer one small dot at a time. Single-point sources include nozzles and lasers.

sinter

To heat, but not melt, powdered materials in order to fuse them together to create a solid shape. Some powder bed fusion (PBF) processes, such as selective laser sintering (SLS) and direct metal laser sintering (DMLS), use lasers to sinter build materials.

SLM

Selective laser melting. A powder bed fusion (PBF) process that builds a part using a laser to melt together successive layers of powdered metals. SLM is similar to selective laser sintering (SLS) but produces stronger and denser parts by fully melting build materials.

SLS

Selective laser sintering. A powder bed fusion (PBF) process that builds a part using a laser to successively sinter and fuse layers of powdered material, usually polymers or ceramics. SLS can produce complex, detailed parts.

sodium hydroxide

A caustic compound made of sodium, oxygen, and hydrogen. Sodium hydroxide is often used to remove support material from additively manufactured parts.

solid-state weld

A type of weld in which two or more materials have been joined together while below their melting points. Solid-state welds are created during friction welding, ultrasonic welding, and ultrasonic consolidation.

soluble

A material that dissolves when exposed to a solvent, such as water or a liquid chemical. Soluble materials are often used for support during some additive manufacturing methods.

solvent

A chemical material that attempts to dissolve another material. Solvents are sometimes used to remove support material from additively manufactured parts.

sonotrode

A disk-shaped device that directly applies ultrasonic vibrations to the surface of a material. Sonotrodes, or ultrasonic horns, create a solid-state weld between metal foil sheets during ultrasonic consolidation (UC).

specifications

The design parameters that set the limits of acceptable deviation for a part's intended application. Specifications for a part may not be met when using lower quality metal powders as build material in directed energy deposition.

spherical

To have a round, three-dimensional circular, or globular shape. Spherical metal powders are produced using the gas atomization process.

stainless steel

A grouping of steels that contain large percentages of chromium, as well as smaller amounts of nickel, manganese, and/or nitrogen. Stainless steels, which have very high hardness and corrosion resistance, are sometimes used as build material in additive manufacturing.

stereolithography

SLA. A vat photopolymerization process that traces a focused light beam over a layer of photopolymer to selectively cure it. Stereolithography is often used for making softer parts that require a high degree of customization such as dental aligners or hearing aids.

strength

A material's ability to resist forces that attempt to break or deform it. Some additive manufacturing methods, such as binder jetting and vat photopolymerization creates parts with poor strength.

stress

A force that attempts to deform an object. Excess stress may cause a part to break.

substrate

A surface or medium that serves as a base for other materials or components. Some directed energy deposition processes deposit materials onto substrates rather than a build platform.

subtractive manufacturing

Any manufacturing process in which a piece of raw material is machined into a desired final shape through a controlled material removal process. Subtractive manufacturing methods are fast but create a large amount of waste.

superalloys

An expensive, complex metal alloy designed to perform under intense conditions, such as elevated temperatures. Superalloys are also known as high performance alloys.

support material

The substance used to create the support structures for an additively manufactured part. Support material is often slightly different from the build material so that it can be more easily removed once the part is finished.

surface finish

The degree of smoothness on a part's outer surface after it has been manufactured. Surface finish quality varies depending on the additive manufacturing method used and the build parameters.

surface porosity

The amount of small spaces or voids within the surface of a solid material. Surface porosity can lead to cracks and other defects in a metal part.

thermal degradation

Deterioration of a material due to overexposure to heat or sun. Thermal degradation can diminish a material's mechanical properties.

thermal energy

Energy in the form of heat. Thermal energy is used to fuse materials together in some additive manufacturing methods, such as directed energy deposition (DED) and powder bed fusion (PBF).

thermal energy sources

A device that generates power in the form of heat. Thermal energy sources, such as devices that generate electron beams, lasers, and plasma arcs, are used during some additive manufacturing methods.

thermal stress

Damage to a material due to excessive changes in temperature. Thermal stress may occur during additive manufacturing methods, such as powder bed fusion (PBF), causing a part to warp or distort.

thermoplastics

A group of polymers that can be repeatedly heated, shaped, and cooled. Thermoplastics are sometimes used in additive manufacturing methods, including material extrusion and powder bed fusion.

thermoset

A group of polymers that are permanently hardened by heating. Thermosets, also known as thermosetting plastics, have high rigidity and thermal stability.

three-dimensional

3D. Having a length, depth, and width. Three-dimensional models are used to create parts during additive manufacturing processes.

tissue

A group of cells that have a similar structure and purpose. Tissues can be used as build material in some specialized material extrusion systems.

titanium

A silver-gray, nonferrous metal that has a high strength-to-weight ratio, excellent flexibility, and exceptional corrosion resistance. Titanium is sometimes used as build material in additive manufacturing.

tolerances

An unwanted but acceptable deviation from a given dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.

tool steels

A grouping of steels designed to be used as cutting tools, dies, punches, and other tools. Tool steels are designed for toughness, hardness, and wear resistance.

tooling

Assorted tools used in various manufacturing processes. Tooling that is damaged can be repaired using directed energy deposition (DED).

top-down printing

A vat photopolymerization system orientation in which the light source is above the vat and the build platform is inside the vat. Top-down printing systems cure and create part layers by projecting light downward and into a deep vat, while the build platform lowers within the vat as each layer completes.

transducers

A device that converts one form of energy, such as electrical, into another form of energy, such as mechanical. In ultrasonic consolidation (UC), transducers convert electrical energy into ultrasonic vibrations.

transparent

Having the quality of allowing light to pass through. Transparent objects are clear and can be seen through.

tungsten alloys

A material containing larger amounts of tungsten, a gray metal that is very strong at elevated temperatures, along with various, lesser amounts of other metals. Tungsten alloys can be powdered and used as build material in additive manufacturing.

turbine blades

A flat component attached to the rotary axis of a turbine to direct air, steam, or gas flow. Turbine blades can be repaired using directed energy deposition (DED).

two-dimensional

2D. Occurring only in the axes of length and width. Two-dimensional objects are flat and lack height.

ultrasonic additive manufacturing

UAM. A sheet lamination process that uses high-frequency vibrations to bond successive layers of material together to build a final part. Ultrasonic additive manufacturing, or ultrasonic consolidation (UC), most frequently uses sheets of metal foil or tape as build material.

ultrasonic consolidation

UC. A sheet lamination process that uses high-frequency vibrations to bond successive layers of material together to build a final part. Ultrasonic consolidation, or ultrasonic additive manufacturing (UAM), most frequently uses sheets of metal foil or tape as build material.

ultrasonic horn

A disk-shaped device that directly applies ultrasonic vibrations to the surface of a material. Ultrasonic horns, or sonotrodes, create a solid-state weld between metal foil sheets during ultrasonic consolidation (UC).

ultrasonic welding

An industrial technique that uses high-frequency vibrations to permanently bond together two separate components in order to make one new part. Ultrasonic welding is used to bond together material layers during ultrasonic consolidation (UC), or ultrasonic additive manufacturing (UAM).

ultraviolet lamp

UV lamp. A light source that steadily or in flashes emits ultraviolet light. Ultraviolet lamps are often used in material jetting to flash cure thermoset build materials.

ultraviolet light

UV light. A potentially harmful wavelength of light that is below, or shorter, than violet on the light spectrum. Ultraviolet light is used to selectively solidify liquid photopolymer in material jetting and vat photopolymerization.

ultraviolet oven

UV oven. Equipment that exposes material to ultraviolet light from all directions. Ultraviolet ovens are sometimes used to cure additively manufactured parts.

undercuts

A part feature, such as a protrusion or depression, that will keep a two-piece part from separating. Undercuts, which can be internal or external, are able to be made using additive manufacturing methods.

uniform

To be constant and unchanging. Uniform metal powders are produced more frequently using gas atomization rather than water atomization.

UV light

Ultraviolet light. A potentially harmful wavelength of light that is below, or shorter, than violet on the light spectrum. UV light is used to selectively solidify liquid photopolymer in material jetting and vat photopolymerization.

vacuum chamber

A sealed enclosure from which air is removed by a vacuum pump. Vacuum chambers surround the entire build area in powder bed fusion (PBF) systems.

vat

An industrial receptacle used to hold fluids. Vats are often used to hold liquid photopolymers in vat photopolymerization.

vat photopolymerization

An additive manufacturing method in which a part is built by curing layers of a photopolymer with ultraviolet (UV) light. Vat photopolymerization processes include stereolithography (SLA) and digital light processing (DLP).

vertically

Perpendicular to the horizon or ground. The build platforms of many additive manufacturing systems often move vertically or up and down.

visual prototypes

A part model that is usually for display purposes and used to illustrate and supplement verbal or written information. Visual prototypes, which are not as strong or durable as other types of prototypes, can be made using sheet lamination.

voids

An empty space between the layers or particles of a part. Voids occur when material layers or particles do not fuse correctly and lower the properties of the part, such as strength and hardness.

warp

To become disfigured, usually by bending or twisting. Parts may warp due to thermal stress produced during some additive manufacturing methods.

water atomization

An atomization process that creates powder by breaking up liquid into droplets using high-pressure water. Water atomization produces irregularly shaped and sized powder particles.

wax

A malleable, water-resistant organic material with a low melting point. Wax is sometimes used as a support material during material jetting.

wear-resistant coating

A finish used to protect a material from gradual erosion. Wear-resistant coatings can be added to parts using directed energy deposition (DED).

welding head

A solid metal rod that holds a disk-shaped sonotrode, or ultrasonic horn, and has a transducer on each of its ends. A welding head applies ultrasonic vibrations as it rolls over the top of metal foil sheets during ultrasonic consolidation (UC).

workpiece

A part that is subjected to one or more manufacturing procedures. Workpieces may be subject to cutting, welding, forming, or other operations.