What Is 3D Printing Filament?

3D printing filament is thermoplastic material wound on a spool that gets melted and extruded through a nozzle to create 3D printed objects layer by layer.

The Basics

Filament is the "ink" of FDM (Fused Deposition Modeling) 3D printing. It's a long strand of plastic material, typically 1.75mm or 2.85mm in diameter, wound onto a spool. During printing, the filament is fed into a heated nozzle where it melts and is deposited precisely to build up your 3D object one thin layer at a time.

Think of it like a hot glue gun, but with much more precision and control. The printer heats the plastic just enough to make it flow, deposits it exactly where needed, and it quickly solidifies as it cools.

Common Filament Diameters

1.75mm

Most Common

Used by most modern printers including Bambu Lab, Prusa, Creality, and Ender series. Requires less force to push through the extruder.

2.85mm (3mm)

Less Common

Used by some Ultimaker and older printers. Marketed as 3mm but actually 2.85mm. More material per mm but requires more force to extrude.

Main Types of Filament

Material Difficulty Best For
PLA Easy Beginners, decorative prints, prototypes
PETG Moderate Functional parts, durability, outdoor use
ABS Hard Heat resistance, automotive parts
TPU Moderate Flexible parts, gaskets, phone cases

How Filament Works

  1. Loading: Filament spool is mounted on the printer and threaded through the extruder
  2. Feeding: The extruder gear grips and pushes filament forward
  3. Heating: Filament enters the hot end where it's heated to melting temperature (typically 180-260°C depending on material)
  4. Extrusion: Molten plastic is pushed through a small nozzle opening (typically 0.4mm)
  5. Deposition: Material is precisely placed on the build plate or previous layer
  6. Cooling: Plastic quickly solidifies as it cools, forming a solid layer
  7. Layer Building: Process repeats thousands of times, building up the object layer by layer

Spool Sizes

Filament typically comes in these weights:

Calculate remaining filament

Key Properties to Consider

Printing Temperature

Different materials require different nozzle temperatures. PLA prints at 190-220°C while ABS needs 230-260°C.

Strength

Some filaments like PETG are strong and impact-resistant, while PLA is more brittle.

Flexibility

Most filaments are rigid, but TPU is rubber-like and flexible.

Heat Resistance

PLA softens around 60°C, while ABS and PETG can withstand higher temperatures.

Storage and Care

Filament absorbs moisture from air, which can cause print quality issues:

Learn about drying filament

Specialty Filaments

Beyond basic materials, specialty filaments offer unique properties:

Getting Started

If you're new to 3D printing:

  1. Start with PLA filament - it's the easiest to print
  2. Buy from reputable brands for consistent quality
  3. Check your printer's filament diameter (usually 1.75mm)
  4. Follow the temperature guidelines on the spool
  5. Store properly to keep it dry

Next Steps