Plain-language definitions of 50+ 3D printing terms — from processes and materials to file formats and finishing techniques. Bookmark this page as your go-to reference.
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A common FDM thermoplastic with good impact resistance and heat tolerance (up to ~100°C). ABS shrinks as it cools, which can cause warping and layer delamination without a heated enclosure. Used for automotive parts, electronics housings, and LEGO bricks. Produces styrene fumes — requires ventilation. Largely replaced by ASA for outdoor applications and PETG for general use.
The formal industry term for 3D printing — building objects by adding material layer by layer, as opposed to subtractive manufacturing (CNC machining, which removes material) or formative manufacturing (injection molding, which shapes material). "Additive manufacturing" is used in engineering, aerospace, and medical contexts; "3D printing" is the common consumer term for the same technology family.
The property of having different mechanical strengths in different directions. Most 3D printed parts are anisotropic — they're stronger along the print plane (X-Y) than between layers (Z direction). This is particularly relevant for FDM and SLA. Understanding anisotropy is critical for designing parts that will be loaded in specific directions. SLS nylon is more isotropic than FDM, which is one reason it's preferred for structural parts.
An FDM thermoplastic similar to ABS but with superior UV resistance and weatherability. ASA maintains its color and mechanical properties under prolonged sun exposure — ABS yellows and becomes brittle. The standard choice for outdoor-facing printed parts. Used in automotive exterior trim, signs, enclosures, and outdoor fixtures. Slightly more expensive than ABS but behaves similarly on most FDM machines.
The ability of a print's first layer to stick to the print surface during an FDM print. Poor bed adhesion causes the print to warp or detach mid-print. Improved by: leveling the build plate accurately, using a heated bed, applying adhesion aids (glue stick, hairspray, PEI sheet, BuildTak surface), and correct first-layer height calibration. Different materials require different bed temperatures — PLA 50–60°C, PETG 70–80°C, ABS 100–110°C.
A 3D printing process that deposits a liquid binding agent onto a powder bed (metal, ceramic, or sand) to bond particles layer by layer. The resulting "green part" is then sintered in a furnace to produce the final dense part. Used for metal parts (ExOne, Desktop Metal), full-color sand casting cores, and ceramic applications. Produces higher-volume metal parts faster and cheaper than DMLS for many applications, but results in slightly lower density than sintering-based processes.
An FDM capability where the printer spans a horizontal gap between two support points without support material underneath. Good bridging ability depends on cooling speed and material properties. PLA bridges well (up to 50–80mm in good conditions). PETG and ABS bridge less cleanly. Bridging quality is tested with calibration prints — improving bridging reduces the need for support structures, which saves material and post-processing time.
The maximum physical size of an object that can be printed in one run on a given machine, expressed as X × Y × Z dimensions (e.g., 250 × 210 × 210mm for a popular desktop FDM printer). Parts larger than the build volume must be split, printed in sections, and assembled. Large-format industrial printers have build volumes measured in meters; desktop machines typically have build volumes in the 15–35cm range.
A photopolymer resin formulation designed to burn out completely in a casting investment without leaving ash or residue. Used in jewelry and fine art metalworking to produce master patterns that are then used in lost-wax casting to create gold, silver, or bronze parts. Standard engineering resins do not burn out cleanly and contaminate casting molds. Castable resins must be printed at jewelry-grade resolution (25–50 micron layer height).
Nylon filament or powder blended with chopped carbon fiber to increase stiffness and reduce weight. Printed CF nylon is stiffer than standard nylon and has a lower coefficient of thermal expansion. Available in FDM filament (short chopped fibers) and SLS powder. Continuous carbon fiber (Markforged CFF) is a distinct, stronger process that embeds long continuous fiber strands. CF nylon abrades brass nozzles rapidly — hardened steel nozzles are required.
A proprietary process developed by Markforged that embeds continuous strands of carbon fiber, fiberglass, or Kevlar into nylon parts during FDM printing. CFF parts achieve strength-to-weight ratios approaching aluminum, far exceeding standard FDM. Used in aerospace, robotics, motorsport, and tooling applications. Different from "carbon fiber FDM" which uses chopped short fibers that add stiffness but not continuous-fiber-level strength.
The process of rapidly cooling each printed layer to solidify it before the next layer is deposited. Critical for FDM print quality — inadequate cooling causes stringing, overhangs to droop, and bridging failures. PLA requires aggressive cooling (high fan speed). PETG prints better with moderate cooling. ABS and nylon require minimal or no cooling to prevent layer delamination and warping. Most FDM slicers have cooling profiles that adjust fan speed based on layer time.
A photopolymer resin printing process that uses a digital projector to flash cure an entire layer at once (vs. SLA which traces each layer with a laser). DLP is typically faster than SLA for small to medium objects because it cures full layers simultaneously. Resolution is determined by the projector's pixel density — fine detail can degrade at larger build areas where each pixel covers more physical area. Common in dental and jewelry applications. Often grouped with SLA as "resin printing."
A metal 3D printing process that uses a high-power laser to fuse metal powder particles layer by layer. Produces fully dense, high-strength metal parts in stainless steel, titanium, aluminum, Inconel, cobalt chrome, and other alloys. Used in aerospace, medical implants, tooling, and motorsport. "DMLS" is technically an EOS GmbH trademark; the more general process term is Powder Bed Fusion (PBF) or Selective Laser Melting (SLM). The terms are often used interchangeably in practice.
A metal powder bed fusion process that uses an electron beam (rather than a laser) to melt metal powder. EBM operates in a vacuum and produces parts at elevated temperatures, resulting in lower residual stresses than laser-based processes. Particularly well-suited to titanium alloys for medical implants. The Arcam system (now owned by GE Additive) is the dominant EBM platform. Less common than DMLS but preferred for specific medical and aerospace titanium applications.
A common FDM defect where the first layer(s) of a print spread out slightly wider than the designed dimension, creating a visible "foot" at the base. Caused by excessive first-layer squish (print head too close to bed), excessive bed temperature, or insufficient cooling of the first layer. Corrected by raising the Z-offset slightly, reducing bed temperature, or enabling first-layer cooling.
The most common desktop 3D printing process. A thermoplastic filament is heated to its melting point and extruded through a nozzle, building parts layer by layer on a flat build plate. Also called FFF (Fused Filament Fabrication — the non-trademarked equivalent). Materials include PLA, PETG, ABS, ASA, nylon, TPU, PEEK, and many others. Resolution is limited by nozzle diameter (typically 0.4mm) and layer height (0.1–0.3mm). The most accessible and affordable 3D printing technology.
The generic, non-trademarked term for the same process as FDM. "FDM" is technically a trademark of Stratasys. "FFF" is used in academic and open-source contexts to avoid trademark issues. Functionally identical to FDM.
The feedstock for FDM/FFF 3D printers. Thermoplastic material wound on spools, available in 1.75mm diameter (most common) and 2.85mm (less common, used by some Ultimaker and larger machines). Sold by weight (typically 1kg spools) in a wide range of materials and colors. Material quality varies significantly — cheap filaments can have inconsistent diameter, moisture contamination, and color batch variation that causes print problems.
The machine instruction language used to control 3D printers (and CNC machines). Slicing software converts 3D model files (STL, OBJ) into G-code that tells the printer exactly where to move, how fast, at what temperature, and how much material to extrude. Most users never interact with raw G-code directly — the slicer handles the conversion. Some advanced users manually edit G-code to fine-tune specific behaviors.
The heated assembly in an FDM printer that melts the filament and extrudes it through the nozzle. Consists of a heater block, thermistor (temperature sensor), heater cartridge, heat break, and nozzle. Hot end temperature depends on material — PLA 190–220°C, PETG 230–250°C, ABS 230–250°C, PEEK 360–400°C. High-temp materials require all-metal hot ends; standard PTFE-lined hot ends are limited to approximately 240°C.
The internal structure of a 3D printed part. Rather than printing solid, most FDM software fills the interior with a geometric pattern at a specified density percentage. Common patterns include grid, gyroid, honeycomb, and cubic. 15–20% infill is standard for non-structural parts. 40–80% infill for structural loads. 100% infill for maximum strength (rarely needed). Higher infill increases strength, weight, and print time. Gyroid infill is popular because it provides more uniform strength in all directions than grid patterns.
The thickness of each printed layer, measured in millimeters or microns. A key quality parameter — smaller layer heights produce smoother surfaces and finer detail but increase print time. Typical FDM layer heights: 0.1mm (fine, slow), 0.2mm (standard), 0.3mm (fast, visible layers). SLA layer heights: 0.025–0.1mm. SLS layer heights: 0.1–0.15mm. Layer height is limited to approximately 75% of the nozzle diameter in FDM.
A metal casting method where a wax (or castable resin) master pattern is embedded in casting investment (a plaster-like material), which is then heated to burn out the wax pattern, leaving a cavity that is filled with molten metal. The investment is broken away to reveal the finished casting. 3D printing has largely replaced hand-carved wax masters in jewelry production — the precision and design freedom of 3D printing combined with the material quality of casting is a highly effective workflow.
A family of processes that produce metal parts directly — including DMLS/SLM (laser powder bed fusion), EBM (electron beam melting), DED (directed energy deposition), and binder jetting. Metal printing produces parts with mechanical properties comparable to conventionally manufactured metal parts. Used in aerospace, medical implants, motorsport, and tooling. Significantly more expensive than polymer printing — parts typically start at $100–$500+ for small components.
HP's powder bed fusion process that uses inkjet heads to apply fusing and detailing agents across a nylon or polypropylene powder bed, then applies an infrared energy source to cure. MJF produces parts faster than traditional SLS and with better dimensional accuracy. The resulting parts are dark gray and slightly more isotropic than SLS. Widely used for functional nylon parts in automotive, industrial, and consumer product applications. Requires professional-grade industrial equipment — available through service bureaus, not desktop machines.
The small orifice at the end of the FDM hot end through which melted filament is extruded. Standard nozzle diameter is 0.4mm (balances speed, detail, and strength). Smaller nozzles (0.2, 0.25mm) produce finer detail but are slow and clog easily. Larger nozzles (0.6, 0.8, 1.0mm) print faster for large structural parts. Material matters: brass nozzles are standard but wear rapidly with abrasive filaments (carbon fiber, glow-in-the-dark, metal-fill). Hardened steel or ruby-tipped nozzles required for abrasive materials.
A family of engineering thermoplastics used in both FDM (PA6, PA12 filaments) and SLS (PA12 powder). Known for toughness, fatigue resistance, and moderate heat resistance (80–100°C continuous). PA12 (nylon 12) is the most common SLS powder — produces strong, flexible-to-semi-rigid parts suitable for functional prototypes and end-use parts. Nylon absorbs atmospheric moisture aggressively, which degrades print quality — dry storage (vacuum sealed or desiccant boxes) is essential.
A 3D geometry file format that, unlike STL, can carry UV texture maps and material assignments. Commonly used when color or surface texture information needs to accompany the mesh. Most service bureaus accept OBJ alongside STL. OBJ files can be larger than equivalent STL files because they carry additional data. For 3D printing, the UV map data is typically ignored by slicers — the mesh geometry is what matters.
A portion of a print that extends horizontally past the layer below it. FDM prints can handle overhangs up to approximately 45–50° from vertical without support — beyond that, the layer has insufficient foundation and droops or fails. SLA/DLP and SLS handle steeper overhangs differently. Overhang angle is a key design consideration — redesigning a feature to reduce overhang angle (or adding a chamfer/fillet) can eliminate the need for support structures.
The technical name for nylon. PA6 (nylon 6) and PA12 (nylon 12) are the most common variants in 3D printing. PA12 is preferred for SLS printing due to better dimensional stability. See Nylon for full details.
A high-performance engineering thermoplastic with excellent mechanical properties, chemical resistance, and heat tolerance (continuous use to 250°C). Biocompatible and sterilizable, making it important for medical device applications. Printing PEEK requires high-temp FDM machines (print temperatures 360–400°C, heated enclosures). Available at specialized industrial bureaus; not available on standard desktop machines. Significantly more expensive than commodity plastics ($200–$500/kg filament vs. $20–$30/kg PLA).
One of the most popular FDM materials, combining ease of printing (similar to PLA) with better impact resistance and higher temperature tolerance than PLA (~80°C heat deflection). Does not warp or require heated enclosures. Excellent layer adhesion produces strong, semi-flexible parts. Food-safe grades exist but require appropriate handling and testing. The go-to material for functional parts where PLA would fail under mechanical load or elevated temperature. Slightly stringy compared to PLA — requires tuned retraction settings.
The most widely used desktop FDM material. Derived from corn starch or sugarcane — biodegradable under industrial composting conditions (not home composting). Prints at low temperatures (180–220°C), requires no heated bed, and produces low emissions. Easy to sand and paint. Limitations: low heat tolerance (~55–60°C heat deflection — degrades in hot cars), brittle compared to PETG or nylon, and degrades with UV exposure over months. Best for: prototypes, display models, items not exposed to heat, moisture, or UV.
Any finishing work done after a part comes off the printer. For FDM: support removal, sanding, priming, painting, vapor smoothing (acetone for ABS). For SLA: isopropyl alcohol wash, UV curing, support removal, sanding. For SLS: powder removal, media blasting, dyeing, infiltration. For metal: support removal, heat treatment, CNC finishing, polishing. The amount of post-processing required varies significantly by application — some industrial SLS parts need only powder removal; some hero props require days of finishing work.
The process family that includes SLS, DMLS, SLM, MJF, and EBM — all processes that selectively fuse particles within a powder bed. The general term "powder bed fusion" covers all these processes when distinguishing them from FDM (extrusion-based) or SLA (photopolymer-based) printing.
The photosensitive liquid material used in SLA, DLP, and MSLA printing. UV light cures (hardens) the resin layer by layer. Available in standard (rigid), flexible, elastic, castable, water-washable, engineering, and biocompatible formulations. Resin handling requires nitrile gloves and eye protection — uncured resin is a skin sensitizer. Waste resin must be cured before disposal. Higher-quality resins produce better-looking, stronger parts but cost more ($30–$200/liter vs. $15–$30/liter for commodity resins).
An FDM setting that pulls the filament back slightly when the print head moves between features without printing, to prevent "stringing" (thin plastic threads left across open spaces). Retraction distance and speed are tuned per material — too little retraction causes stringing, too much can cause clogs or gaps in extrusion. PETG is particularly prone to stringing and requires careful retraction tuning.
A company that offers 3D printing as a paid service, using professional-grade equipment. You upload a file, specify material and quantity, and receive finished parts. Ranges from small local shops to large on-demand services (Xometry, Protolabs, Craftcloud). Service bureaus provide access to industrial processes (SLS, DMLS, MJF, large-format FDM) that are too expensive for individual purchase. The entire 3DPrintMap directory is a searchable index of service bureaus across the US.
Fusing material particles together using heat without fully melting them. In SLS, a laser sinters (fuses) polymer powder particles together. In binder jetting, the green part is sintered in a furnace after printing to achieve full density. In metal injection molding (MIM), sintering follows molding. Sintered parts are typically 95–99% dense — slightly less than fully melted-and-solidified parts, which can affect some mechanical properties.
The first commercial 3D printing process (patented by Chuck Hull in 1986). A UV laser traces each layer of a photopolymer resin, curing it from liquid to solid. Produces the highest surface quality of any 3D printing process — smooth, isotropic parts with layer heights as fine as 25 microns. Used for jewelry, dental, medical models, precision prototypes, and display models. Parts require a post-cure UV step after printing. The term "SLA" is sometimes used loosely for all resin printing, including DLP and MSLA.
Software that converts a 3D model (STL/OBJ/3MF) into print instructions (G-code). The slicer determines layer height, infill pattern and density, support generation, print speed, temperatures, and all other print parameters. Common FDM slicers: PrusaSlicer, Bambu Studio, Ultimaker Cura, Simplify3D. Common resin slicers: ChituBox, Lychee Slicer. Getting good slicer settings for a specific material and machine is a significant portion of FDM 3D printing skill.
A metal powder bed fusion process that fully melts (rather than sinters) metal powder with a high-power laser. SLM produces fully dense parts (99.9%+ density) with excellent mechanical properties. Technically different from DMLS (sintering), though the terms are used interchangeably in commercial contexts. SLM processes metal alloys including stainless steel, titanium, aluminum, cobalt chrome, and Inconel. The dominant metal 3D printing process for aerospace and medical applications.
A powder bed fusion process that uses a CO2 laser to selectively sinter (fuse) nylon, polypropylene, or other polymer powders. Parts are built embedded within the powder bed — no support structures needed, which enables complex internal geometries and interlocking parts. SLS nylon is the workhorse of industrial polymer 3D printing — strong, functional parts used in automotive, aerospace, medical devices, and consumer products. Requires industrial-grade equipment and facilities; available through professional service bureaus.
The universal file format for 3D printing. An STL file represents a 3D surface as a mesh of triangular facets. All major CAD software exports STL. All 3D printing slicers accept STL. Limitations: no color information, no material assignment, no scale unit encoding (mm vs. inches must be confirmed separately). 3MF is a newer format that addresses these limitations, but STL remains the dominant interchange format. A "watertight" (manifold) mesh — no holes or overlapping faces — is required for a printable STL.
Thin strands of plastic left across open spaces in an FDM print when the print head travels between features while still slightly oozing material. Caused by insufficient retraction, excessive print temperature, or high print speed. Some materials (especially PETG and flexible TPU) are prone to stringing. Minor stringing can be removed with a heat gun or precision knife in post-processing. Major stringing indicates slicer settings need adjustment.
Temporary structures printed beneath overhanging features to prevent them from collapsing during printing. In FDM, supports are printed in the same or a different material and removed by hand or with pliers after printing — leaving contact marks on the surface. In SLA/DLP, supports are resin pillars that are cut away after printing. SLS and MJF do not require separate support structures — the surrounding powder provides support — which is a major advantage for complex geometries. "Dissolvable supports" (PVA, HIPS) dissolve in water or limonene, leaving cleaner surfaces on FDM multi-material machines.
The allowable dimensional variation in a printed part. Expressed as ±X mm. Typical FDM tolerances: ±0.2–0.5mm. Typical SLA tolerances: ±0.1–0.2mm. Typical SLS tolerances: ±0.2–0.3mm. Metal DMLS: ±0.05–0.1mm. Tolerances affect whether printed parts will fit together (mating components), interface correctly with off-the-shelf hardware, and meet engineering specifications. Designing with appropriate tolerance clearances for the process being used avoids assembly problems.
A flexible FDM filament with rubber-like properties. Shore hardness varies by formulation — typically 87A to 95A. Used for gaskets, seals, flexible hinges, anti-vibration mounts, shoe soles, phone cases, and wearables. Slower to print than rigid materials (oozes more easily at speed). Requires Bowden tube setup care — flexible filaments can buckle in Bowden feeders; direct drive extruders are preferred. 100% infill is often needed for parts that must be uniformly elastic.
Polyetherimide, sold under the Ultem brand by SABIC. A high-performance thermoplastic with exceptional heat resistance (continuous use to ~170–215°C depending on grade), chemical resistance, and flame retardancy. Ultem 9085 is aerospace-certified (FAA flame, smoke, and toxicity rated) and used extensively in aircraft interiors and defense applications. Requires high-temp FDM machines (print temperatures 350–400°C). Available through Stratasys systems and some open-platform high-temp printers.
The process category that includes SLA, DLP, and MSLA (masked SLA, also called LCD printing). All use UV light to cure photopolymer resin in a vat (container). Differences relate to the light source: SLA uses a UV laser, DLP uses a digital projector, MSLA uses an LCD screen as a mask. All produce high-detail, smooth-surface parts. Consumer MSLA (LCD) printers have become extremely affordable, bringing resin printing to hobbyist price points.
The thickness of the outer shell of a 3D printed part. In FDM, wall thickness is a multiple of nozzle diameter — with a 0.4mm nozzle, walls can be 0.4mm, 0.8mm, 1.2mm, etc. Thicker walls provide more strength and are less sensitive to layer line visibility. Minimum wall thickness for FDM is typically 0.8–1.2mm for a printable feature. In SLA, walls as thin as 0.3–0.5mm are printable. Understanding minimum wall thickness prevents designing features that cannot be printed reliably.
Distortion that occurs in FDM printing when the printed material cools unevenly, causing the corners or edges of a print to lift off the build plate. Most common with ABS, nylon, and PC — materials that have high thermal contraction and require controlled cooling. Prevented by: heated enclosures, higher bed temperatures, correct bed adhesion surfaces, and minimizing part surface area on the bed through orientation changes. PLA and PETG warp minimally under normal conditions.
A visible vertical line on the exterior of FDM prints where each layer starts and ends (the layer transition point). Can be minimized by "hiding" the seam in a corner or less visible location (slicer setting: seam alignment "corners" or "sharpest corner"). "Spiral vase mode" (outer contour printing) eliminates the Z-seam entirely but can only print hollow single-wall objects. Minor Z-seams can be sanded away in post-processing.
Now that you know the terminology, find a local service bureau that offers the process you need.