What is a filament? A filament is a thin, flexible thread of material that your 3D printer melts and deposits layer by layer to create solid objects. If you own an FDM 3D printer, understanding filament is key to getting quality prints every time.
3D printer filament comes in dozens of materials, from basic plastics to advanced composites.
Each type has different melting points, strength levels, and uses. The wrong choice can lead to failed prints, warped parts, or weak layers.
This guide breaks down everything you need to know about filament materials, properties, and selection. You'll learn which types work best for your projects and how to match filament settings to your printer for consistent results.
Quick Takeaways 💡:
- What is a Filament? It's a thermoplastic material, wound onto a spool, that serves as the raw material (like ink or toner) for most common 3D printers.
- How it Works The printer pulls the filament into a heated nozzle (hotend), melts it, and extrudes it layer by layer to build an object.
- Common Types: PLA is great for beginners, PETG is a strong all-rounder, and TPU is for flexible parts.
- Key Sizes The most common filament diameters are 1.75mm and 2.85mm.
So, What is a Filament in 3D Printing Exactly?
At its core, 3D printer filament is a specially designed thermoplastic wire. "Thermo-plastic" simply means it's a plastic that becomes soft and moldable when heated and solidifies when cooled. This property is what allows a 3D printer to create objects.
The filament is manufactured to an exact diameter and wound onto a spool, which is then mounted onto the printer.
Why Is Filament Diameter Important?
3D printer filament comes in two standard sizes: 1.75mm and 2.85mm. Your printer only works with one of these sizes.
Using the wrong diameter causes serious problems. The extruder and hotend are built for a specific size. When you use the correct diameter, melted plastic flows smoothly through the system.
Wrong size filament creates these issues:
- Clogs in the extruder
- Jams that stop your print
- Poor print quality
- Wasted time and materials
Most newer printers use 1.75mm filament. Older printers often use 2.85mm. Check your printer manual to find the right size before buying filament.
The diameter must be precise. Good filament has tight tolerances, usually within 0.02mm. This consistency helps your printer push the exact amount of plastic needed for each layer.
The Role of the Spool
Filament spools do more than just hold the plastic wire. They keep filament organized and prevent tangles during printing.
A good spool lets filament unwind smoothly. The printer pulls filament as it prints, so the spool must rotate freely. A tangled filament can stop your print and waste hours of work.
Always check these things before printing:
- No knots or tangles in the filament
- The spool rotates freely on your printer
- Filament feeds smoothly to the extruder
- No loose ends that might catch
Store spools in dry places. Moisture can make some filaments brittle or cause poor print quality. Many people use sealed containers with silica gel packets to keep filament dry.
📌Also Read: Understanding and Preventing Filament Tangles: A User's Guide
How Filament Becomes a 3D Print: The Process
The transformation from solid filament to finished 3D print happens through three main stages. Your printer uses mechanical force, heat, and precise movement to build objects one thin layer at a time.
Step 1: The Extruder Grips and Pushes
The extruder is the first stop in how 3D printing works. This component contains a motor connected to a gear system with teeth that grip your filament.
Key functions of the extruder:
- Pulls filament from the spool
- Controls the exact speed of filament feeding
- Pushes material toward the hotend
The extruder motor responds to commands from your printer's control board. When your print needs more material, the motor spins faster. When it needs less, the motor slows down or stops completely.
This precise control lets your printer create detailed features. Thin walls need less filament flow, while solid areas need more.
Step 2: The Hotend Melts the Plastic
After leaving the extruder gears, the filament travels into the hotend. This is a heated block with a small nozzle opening, commonly about 0.4 mm wide.
Typical print temperatures by material:
- PLA: 190-220°C
- ABS: 220-250°C
- PETG: 230-250°C
The hotend heats the filament to its melting point. The solid plastic becomes a thick, honey-like liquid ready for printing.
The nozzle stays at the exact temperature needed. Too hot and the plastic burns. It's too cold, which clogs the nozzle.
Step 3: Building Layer by Meticulous Layer
The printer’s print head moves across the build platform along a pre-programmed path. The molten filament is deposited in precise spots, cooling and hardening within seconds.
The layer-by-layer process:
- The print head lays down the first layer on the build plate
- The platform lowers slightly (or the print head rises)
- The next layer is deposited on top of the previous one
- The process repeats until the object is complete
Most layers measure 0.1–0.3 mm thick. A 10 cm-tall print at 0.2 mm layer height, for example, requires about 500 layers. Each new layer bonds to the one beneath it, producing a strong, finished part.
Common Filament Types Explained
Each filament type has different strengths, print requirements, and best uses. Six polymers make up most 3D printing materials: PLA, PETG, ABS, TPU, nylon, and polycarbonate.
1. PLA (Polylactic Acid)
PLA is the most beginner-friendly filament you can use. It prints at low temperatures and sticks well to build plates without heated beds.
Key Benefits:
- Easy to print with minimal warping
- Low odor and biodegradable
- Sharp detail and smooth surface finish
- Works on any printer type
Print Settings:
- Nozzle temperature: 190-220°C
- Bed temperature: 50-60°C (optional)
- Print speeds: 40-80mm/s
PLA works best for prototypes, decorative items, and indoor parts. It becomes soft around 60°C, so avoid using it for car parts or hot environments.
The material comes in many colors and specialty versions like wood-filled or glow-in-the-dark. You can print PLA right out of the box with basic printer settings.
2. PETG (Polyethylene Terephthalate Glycol)
PETG Polyethylene Terephthalate Glycol) combines the ease of PLA with the strength of ABS. It bonds layers extremely well and resists impact better than most other filaments.
Key Benefits:
- Strong layer adhesion prevents splitting
- Chemical-resistant and food safe
- Clear versions available
- Less warping than ABS
Print Settings:
- Nozzle temperature: 230-250°C
- Bed temperature: 70-80°C
- Print speeds: 30-60mm/s
PETG can string between parts during printing. Lower your print temperature by 5-10°C and increase travel speed to reduce stringing.
Use PETG for functional parts, containers, phone cases, and mechanical components. It handles stress and flexing better than PLA while staying easier to print than ABS.
The material works well for parts that need transparency or chemical resistance. PETG also machines and post-processes easily.
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3. ABS(Acrylonitrile Butadiene Styrene)/ASA
ABS and ASA handle high temperatures and outdoor conditions better than PLA or PETG. ASA adds UV resistance for parts used in sunlight.
Key Benefits:
- Heat resistant up to 100°C
- Strong and impact-resistant
- Easy to sand and machine
- ASA resists UV damage
Print Settings:
- Nozzle temperature: 240-260°C
- Bed temperature: 80-110°C
- Enclosure recommended
ABS warps easily without proper temperature control. Use an enclosed printer or build a simple enclosure around your print area.
Warping Control Tips:
- Keep chamber temperature around 40-60°C
- Use ABS slurry or hairspray for bed adhesion
- Print with 0.2mm first layer height
- Avoid drafts and temperature changes
Use ABS for car parts, tool handles, and outdoor equipment. ASA works better for parts exposed to sunlight, like garden tools or automotive trim.
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📌Read More: What is ABS Filament? Uses, Pros, and Cons for 3D Printing
4. TPU (Thermoplastic Polyurethane)
Flexible filaments like TPU stretch and bend without breaking. Shore hardness ratings indicate the flexibility of different TPU types.
Shore Hardness Guide:
- 85A: Very flexible, rubber-like
- 90A: Flexible but firm
- 95A: Semi-flexible, good for beginnings
Print Settings:
- Nozzle temperature: 210-230°C
- Bed temperature: 40-60°C
- Print speeds: 15-30mm/s (slow)
Print TPU slowly to prevent jamming in the extruder. Direct drive extruders work better than Bowden systems for flexible filaments.
Printer Setup Tips:
- Reduce retraction to 1-2mm
- Increase extruder tension slightly
- Use higher layer heights (0.2-0.3mm)
Use TPU for phone cases, gaskets, shoe soles, and grip handles. The material absorbs shock and provides excellent grip surfaces.
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📌Also Read: Siraya Tech Flex TPU Filaments Achieve ISO Biocompatibility Certification
5. Nylon & Blends
Nylon creates some of the strongest printed parts available. It resists wear, chemicals, and high temperatures better than most other filaments.
Key Benefits:
- Extremely strong and durable
- Wear-resistant for moving parts
- Chemical and heat-resistant
- Self-lubricating properties
Print Settings:
- Nozzle temperature: 250-280°C
- Bed temperature: 80-120°C
- Enclosure strongly recommended
Nylon absorbs moisture from the air quickly. Always dry your filament before printing at 60-80°C for 8-12 hours.
Drying and Storage:
- Store in sealed containers with desiccant
- Dry at 80°C for 12 hours if moisture is absorbed
- Wet nylon creates a poor surface finish and weak parts
Bed Adhesion:
- Use PEI sheets or glass with adhesion aids
- Garolite (G10) works well for nylon
- ABS slurry provides good adhesion
Use nylon for gears, bearings, tool parts, and mechanical components. Carbon fiber nylon blends add stiffness for structural applications.
📌Also Read: Decoding High-Temperature Nylon: Why Your FDM Prints Deserve More Than Just "PAHT"
6. Polycarbonate (PC)
Polycarbonate creates the strongest printed parts for extreme conditions. It handles high temperatures and impacts that would break other materials.
Key Benefits:
- Strongest common 3D printing material
- Heat resistant to 140°C
- Excellent impact resistance
- Naturally flame retardant
Print Settings:
- Nozzle temperature: 270-310°C
- Bed temperature: 90-130°C
- Chamber temperature: 60-80°C
PC requires high temperatures that standard hotends cannot reach. Install a hardened steel or hardened nozzle rated for 300°C+.
Equipment Requirements:
- All-metal hotend with high-temp thermistor
- Hardened steel nozzle recommended
- Enclosed chamber essential
How to Choose the Right Filament
The right filament depends on what you plan to print, where it will be used, and what your printer can handle. Selecting the right 3D printing filament is simple when you consider these three main factors in order.
☑️ By Application
Your project's purpose determines which filament properties matter most. Different applications need different strengths and features.
Rapid Prototypes: PLA works best for quick concept models and design testing. It prints fast and easily with good detail. You don't need strength for short-term prototypes.
Jigs and Fixtures: PETG or ABS handle workshop use better than PLA. These need to resist impact and wear from repeated use. Choose materials that won't crack under stress.
Functional End-Use Parts: Consider what forces the part will face. Gears need wear resistance. Brackets need strength. Moving parts need low friction. ASA works for outdoor parts that face the sun and weather.
Aesthetic Models: PLA gives the smoothest surface finish for display pieces. Silk filaments add shine. Wood-filled filaments sand and stain like real wood for decorative items.
☑️ By Environment
The conditions where your print will live determine which materials will last. Think about the end use of your part before picking a filament.
Heat Exposure
- PLA: Good up to 140°F
- PETG: Handles up to 180°F
- ABS: Works to 200°F
- ASA: Best for 200°F+ applications
UV and Weather: ASA resists sun damage better than ABS or PLA. Standard PLA breaks down in direct sunlight within months. ABS turns brittle and yellow outdoors.
Chemical Contact: PETG resists most household chemicals and cleaners. PLA dissolves in some solvents. Check chemical compatibility charts for specific exposures.
Impact and Flexing: TPU handles repeated bending without breaking. PETG absorbs impact better than brittle PLA. ABS is suitable for parts that require some flexibility while remaining rigid.
☑️ By Printer Capability
Your printer limits which filaments you can use successfully. Check these specs before buying new materials.
Temperature Limits
- All-metal hotend: Prints any filament up to 500°F
- PTFE-lined hotend: Limited to 480°F maximum
- Basic hotend: PLA and PETG only (up to 450°F)
Bed Heating: Heated beds help with bed adhesion for ABS, ASA, and PETG. PLA prints fine on cold beds. Most heated beds reach 200°F, which works for common filaments.
Enclosure Requirements: ABS and ASA need enclosed chambers to prevent warping. The enclosure keeps warm air around the print. Open-frame printers struggle with these materials.
Extruder Type: Direct-drive extruders handle flexible filaments like TPU better. Bowden setups work fine for rigid filaments but may jam with soft materials.
Nozzle Material
- Brass: Works for PLA, PETG, ABS, ASA
- Steel: Required for filled filaments with carbon fiber, metal, or wood
- Ruby-tipped: Best for abrasive materials that wear down brass quickly
📌Also Read: Printing Siraya Tech Filaments on Creality K1C ＆ K2 Plus
Conclusion
Filament is the core feedstock that lets FDM printers turn designs into real, useful parts. By understanding what a filament is, how it flows through your machine, and how different materials behave, you can match the right spool to every job.
Compare properties, set the right temps, and keep spools dry for consistent success. Final tip: start with an easy filament for fast wins, then step up to specialty materials as your projects demand.
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FAQs About What Is a Filament
People often ask about the differences between printing materials, storage requirements, and safety concerns. These questions cover material compatibility, lifespan, recycling options, and health considerations.
What is the difference between filament and resin?
Filament is a plastic wire that melts and gets pushed through a heated nozzle to build objects layer by layer. Resin is a liquid plastic that hardens when exposed to UV light.
Filament printers use heat to melt the material. Resin printers use light to cure liquid into solid plastic.
Filament creates objects with visible layer lines. Resin produces smoother surfaces with finer details.
How long does 3D printer filament last?
An unopened filament can last 1-2 years when stored properly. Once opened, most filaments stay good for 6-12 months.
Moisture damages the filament over time. PLA absorbs water from the air and becomes brittle or stringy.
Store your filament in airtight containers with desiccant packets. Keep it away from heat and direct sunlight.
Can you reuse old 3D prints or filament?
You can recycle some 3D prints by shredding them and melting them into new filament. This requires special equipment that most people don't have at home.
Most recycled filament has lower quality than new material. The plastic degrades each time you melt it.
Support material and failed prints can be recycled through some specialized services. Check if your local area has plastic recycling programs that accept 3D printing waste.
Is 3D printer filament toxic to breathe?
Most common filaments like PLA are plant-based and considered very safe, emitting little to no harmful fumes. However, other materials like ABS can release styrene, which can be irritating. It's always best practice to use your 3D printer in a well-ventilated area, regardless of the filament type.
Can I mix brands of filament?
You can use different brands of the same material type on one printer. PLA from various companies will work together.
Each brand may have slightly different melting temperatures. Adjust your printer settings when switching brands.
Avoid mixing different material types, such as PLA and ABS, in the same print job. They have different properties and printing requirements.