The Ultimate FDM 3D Printing Dictionary: Your Complete Guide to FDM Printing Terms

Whether you're just starting your FDM printing journey or looking to expand your knowledge, understanding the terminology is crucial. At Eolas Prints, we believe that knowledge empowers better printing results. This comprehensive dictionary covers everything from basic FDM concepts to the latest 2025 technologies, specifically focused on Fused Deposition Modeling (FDM) printing.

A

Adaptive Layer Height - Dynamic adjustment of layer thickness during printing to balance detail and speed. Thin layers in detailed areas, thicker layers in simple sections.

Adhesion - The bond between print layers or between the first layer and the print bed. Critical for print success and structural integrity.

AMS (Automatic Material System) - Bambu Lab's multi-material system enabling automatic filament changes during printing for multi-colour or multi-material prints.

Annealing - Post-print heat treatment that improves mechanical properties and heat resistance. Particularly effective with PLA Ingeo materials, raising heat deflection temperature to 85°C+.

ASA (Acrylonitrile Styrene Acrylate) - UV-resistant filament for outdoor applications. Superior weathering resistance compared to ABS with similar mechanical properties.

B

Bed Levelling - The process of ensuring the print bed is perfectly parallel to the nozzle path. Modern printers use automatic mesh bed levelling (ABL) for accuracy.

Bed Temperature - The heated surface temperature for the first layer to adhere. PLA: 0-60°C, PETG: 70-90°C, ABS/ASA: 90-110°C.

Bowden Extruder - System where the motor is separate from the hot end, connected by a tube. Lighter print head but less precise flexible filament control vs direct drive.

Bridging - Printing horizontal spans between two supports without additional support material. Tests filament cooling and retraction settings.

C

Cooling Fan - Directs air at the freshly printed layer to solidify it quickly. Essential for overhangs and bridges. TPU and ABS typically need reduced cooling.

CoreXY - Motion system where both X and Y axes move the printhead while Z moves the bed. Faster and more precise than bed-slinger designs. Used in Bambu Lab, Prusa Core One.

Cura - Open-source slicing software by Ultimaker. One of the most widely used FDM slicers with extensive plugin support.

D

Direct Drive - Extruder motor mounted directly on the print head. Better retraction control and flexible filament performance, but adds weight to the carriage.

Door (Enclosure) - Physical barrier around the printer that maintains ambient temperature. Essential for ABS and ASA to prevent warping and layer delamination.

E

Elephant Foot - Flaring at the base of a print caused by excessive bed temperature, too-low first layer height, or over-squishing. Fixable via Z-offset adjustment.

Enclosure - Housing that surrounds the printer to retain heat. Required for engineering-grade filaments. Most Bambu Lab and Prusa XL configurations support enclosures.

Extruder - The mechanism that feeds filament into the hot end. Two types: direct drive (motor on head) and Bowden (motor at frame).

F

FDM (Fused Deposition Modeling) - The most common 3D printing technology. Thermoplastic filament is melted and extruded layer by layer to build objects.

Filament - The raw material used in FDM printing. Standard diameters are 1.75mm and 2.85mm. Common materials: PLA, PETG, TPU, ABS, ASA.

First Layer - The most critical layer in any FDM print. Determines adhesion and overall print success. Speed, temperature, and Z-offset all influence first layer quality.

Flow Rate - The volumetric rate of filament extrusion, typically expressed as a percentage. 100% is calibrated; values above indicate over-extrusion, below indicate under-extrusion.

G

G-Code - Machine language commands sent to the printer. Generated by slicers from 3D models. Controls all movement, temperature, and speed parameters.

Ghosting (Ringing) - Wave-like artifacts on print surfaces caused by vibration during fast direction changes. Reduced by lower acceleration, stiffer frames, or input shaping.

H

Heat Creep - Unwanted heat transfer up the filament path beyond the hot zone. Causes jams, especially with PLA. Prevented by adequate heat break cooling.

Heat Deflection Temperature (HDT) - The temperature at which a material deforms under a specified load. PLA: ~60°C, PETG: ~80°C, ABS/ASA: ~85°C, Ingeo PLA (annealed): 85°C+.

Hot End - The assembly that melts filament for extrusion. Consists of heater block, nozzle, thermistor, and heat break.

I

Infill - The internal structure of a printed object. Expressed as a percentage (0% = hollow, 100% = solid). Pattern (gyroid, honeycomb, grid) affects strength and flexibility.

Input Shaping - Algorithm that compensates for printer resonance to reduce ghosting at high speeds. Standard on Bambu Lab printers and recent Klipper configurations.

J

Jerk - The rate of change of acceleration. Higher jerk values mean faster direction changes but more vibration and potential ghosting artifacts.

K

Klipper - Open-source 3D printer firmware running on a Raspberry Pi. Enables advanced features like input shaping, pressure advance, and high-speed printing.

L

Layer Adhesion - The bond strength between printed layers. Influenced by print temperature, speed, and cooling. Higher temperatures generally improve adhesion but may reduce detail.

Layer Height - The thickness of each printed layer. Typical range: 0.1mm (fine detail) to 0.35mm (fast printing). Generally 25-75% of nozzle diameter.

Linear Advance (Pressure Advance) - Firmware feature that pre-pressurises the nozzle before corners and de-pressurises after. Reduces blobs and improves corner accuracy.

M

Marlin - The most widely used open-source 3D printer firmware. Powers the majority of FDM printers including many Prusa, Creality, and Flashforge models.

Moisture Absorption - Filaments absorb humidity from air, degrading print quality. PETG and TPU are particularly sensitive. Store filament in sealed containers with desiccant.

N

Nozzle - The aperture through which molten filament is extruded. Standard diameter: 0.4mm. Larger nozzles (0.6-1.0mm) print faster; smaller (0.2-0.3mm) give finer detail.

Nozzle Temperature - The extrusion temperature. PLA: 195-220°C, PETG: 230-245°C, TPU: 220-235°C, ABS: 230-250°C, ASA: 240-260°C.

O

Overhang - A section of a print that extends beyond the layer below. FDM typically handles up to 45° without supports; steeper angles require support structures.

Over-extrusion - Too much material being deposited. Causes blobs, zits, and rough surfaces. Corrected by reducing flow rate or increasing retraction.

P

PETG (Polyethylene Terephthalate Glycol) - Popular engineering filament with excellent layer adhesion, chemical resistance, and food safety. Heat deflection: ~80°C.

PLA (Polylactic Acid) - The most widely used FDM filament. Easy to print, biodegradable, and available in dozens of variants including silk, matte, neon, and high-speed formulations.

Pressure Advance - See Linear Advance. Klipper's implementation of the same concept.

Print Speed - Rate of printhead movement during extrusion, in mm/s. Standard PLA: 40-100mm/s. High Speed PLA formulations support up to 300mm/s.

R

Retraction - Pulling filament back into the nozzle during travel moves to prevent stringing. Distance and speed vary by filament type and extruder configuration.

Raft - A sacrificial base layer printed beneath the object to improve bed adhesion and reduce warping, particularly for ABS and ASA.

S

Shore Hardness - Measurement of material flexibility. Used for TPU: Shore A scale (soft rubber) for 93A and below; Shore D scale (harder plastics) for D53, D60.

Slicer - Software that converts 3D models into G-code. Common options: Bambu Studio, PrusaSlicer, Cura, IdeaMaker, OrcaSlicer.

Stringing - Fine threads of filament left between parts during travel moves. Caused by insufficient retraction or too-high print temperature.

Support Structures - Temporary material printed to support overhangs. Removed after printing. Can be same material or water-soluble (PVA) for complex geometries.

T

Temperature Tower - A calibration print that tests multiple temperatures in a single object. Used to identify the optimal print temperature for a specific filament.

TPU (Thermoplastic Polyurethane) - Flexible, rubber-like filament. Available in multiple Shore hardnesses: 93A (medium-soft), D53 (soft), D60 (firmer, UV-resistant). Food safe and skin safe.

Travel Move - Printhead movement without extrusion. Minimising travel reduces stringing risk and print time.

U

Under-extrusion - Insufficient material being deposited. Causes gaps, weak layers, and poor surface finish. Check for clogs, incorrect flow rate, or temperature issues.

V

VICAT Softening Point - Temperature at which a material begins to deform under a standard load. ABS: 106°C, ASA: 105°C. Higher than HDT; relevant for heat-resistant part design.

Volumetric Flow Rate - The actual volume of filament extruded per second (mm³/s). The true limit of a printer's speed, more useful than mm/s alone.

W

Warping - Lifting or curling of print corners due to thermal contraction. Most common with ABS and ASA. Prevented by enclosures, heated beds, and good first-layer adhesion.

Wipe Tower - Structure printed to clean the nozzle between material changes in multi-material printing.

X, Y, Z

XYZ Axes - The three-dimensional coordinate system defining printer movement and object positioning.

Z-Hop - Lifting the nozzle slightly during travel moves to avoid hitting previously printed parts.

Z-Offset - Fine adjustment of the nozzle height relative to the bed for optimal first layer adhesion.

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Why Understanding FDM Terms Matters

At Eolas Prints, we know that mastering FDM printing terminology helps you optimise material selection from our PLA, TPU, PETG, ABS, and ASA range; troubleshoot issues like heat creep, ghosting, and elephant foot; fine-tune settings like linear advance and adaptive layer height; and communicate effectively with our technical support team.

Ready to Apply Your FDM Knowledge?

Now that you understand FDM terminology, you're equipped to get the most from your printer. Browse our premium filaments, all manufactured in-house in Cantabria, Spain with ISO 9001 and ISO 14001 certifications.

Need help optimising your FDM settings? Our team provides technical support to help you achieve perfect results with our high-quality materials.

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