Material:Nylon

MaterialInfoBox Nylon

Synonyms:	PA, Polyamide
Suggested Tools:	3D printer
Contains:	glass fiber (GF), carbon fiber (CF)

Nylon is the common name for a family of synthetic polymers known as polyamides which were first developed by Wallace Carothers at DuPont in the 1930s as a "synthetic silk". Because of the following characteristics the polymer is still used in various fields and applications:

High Strength and Durability: Nylon possesses an excellent strength-to-weight ratio and is incredibly resistant to abrasion.
Elasticity: It can be stretched significantly and will return to its original shape, making it ideal for durable fibers.
Thermal Resistance: It has a relatively high melting point and glass transition temperature for a plastic, allowing it to function in high-heat environments like engine compartments.
Chemical Resistance: It stands up well against oils, greases, and many solvents, though it is notably hygroscopic, meaning it absorbs moisture from the air, which can alter its dimensions and flexibility over time.

3D printing

In additive manufacturing, nylon (often referred to as PA for Polyamide) is considered a "prosumer" or industrial-grade material. While it is more difficult to print than standard materials such as PLA or PETG due to warping and moisture sensitivity, it offers functional capabilities that cheaper plastics cannot match. Based on it's different properties there are various variants enabling easier printing:

PA6 vs. Pa12

The numbers refer to the number of carbon atoms in the polymer’s molecular chains. PA6 is generally considered the "standard" industrial nylon. It has higher impact resistance and better mechanical strength at lower temperatures compared to PA12 and also has a higher melting point (220°C). However, PA6 is highly hygroscopic and absorbs water more aggressively and accommodates about twice as much as PA12. PA6 is used when you need the highest possible strength and stiffness at a lower cost, and where the part will not be exposed to high-humidity environments that could cause it to swell or lose dimensional accuracy.

PA12 contains less amide groups changing it's performance: While the mechanical and thermal performance is slightly reduced, it is more dimensional stable and less hygroscopic compared to PA6 but also a bit more expensive. PA12 is used for precise engineering because it doesn't warp as easily and is excellent for long-term outdoor use, chemical storage, or complex assemblies where parts must fit together perfectly regardless of the weather/moisture.

-GF / -CF

To further enhance the printability and dimensional accuracy glass (-g) or carbon (-c) fibers (f) are added in various amounts. The mechanical properties (besides stiffness) don't benefit from these additives as they reduce the strength of the bond between the lines.

Glass fiber (-gf) parts don't conduct heat and electricity, are heavier, less rigid but also less brittle and cheaper than carbon fiber (-cf) parts. CF-parts are slightly conductive which helps with dissipating static electricity (ESD safe) and almost as rigid as metal (depending on the carbon content percentage) while being very lightweight.

Annealing

Annealing is a post-processing heat treatment used to "relax" a 3D-printed or machined part. During the printing process, nylon is heated and cooled rapidly, which traps internal stresses and leaves the polymer chains in a disorganized, tangled state. Without annealing, the parts are more prone to warping over time and may fail prematurely under load due to these built-in stresses. Annealing accomplishes three main goals:

Relieves Internal Stress: It allows the plastic to "settle," preventing future deformation.
Increases Crystallinity: By holding the plastic at a high temperature, the polymer chains rearrange into a more organized, crystalline structure. This significantly increases the part's tensile strength and stiffness.
Improves Heat Resistance: An annealed part can often withstand higher operating temperatures than a non-annealed one.
Reduced Effect of Hygroscopy: the reduction in performance due to water absorption can be slightly mitigated through the heat treatment.

The Process

Place the part in a temperature-controlled oven.
Gradually raise the temperature to just below the material’s Glass Transition Temperature or slightly above it, depending on the specific nylon grade (usually between 70°C and 130°C for nylon).
Hold the part at this temperature for a set duration (typically 1 hour per millimeter of wall thickness) to ensure the core of the part reaches the same state as the surface.
The oven is turned off and allowed to cool down very slowly with the part still inside. If the part cools too fast, new stresses will form, defeating the purpose of the process.

A Note on Shrinkage: Because annealing reorganizes the molecules into a tighter structure, the part will usually shrink slightly