Engineering filaments like our composite nylon 12 materials have certain limitations and challenges not as prominent with other, easier to print materials such as PETG.
Plastics are hygroscopic and readily absorb moisture from the air. If spools of filament are left out they can gain upwards of 1% of their mass in water content. When wet filament is passed through a hotend, the water boils off as steam and exits the nozzle orifice, causing uncontrolled extrusion of material. If the filament is very wet, you can hear hissing, popping and crackling noises and even see steam or bubbles in the filament when extruding in the air.
This tends to show up in prints as excessive stringing and poor surface quality.
Nylon parts require high temperatures for the deposited material to bond adequately to form strong prints. When printing many small objects, the low thermal mass combined with long layer times means that the material may cool down too much before the new material is deposited resulting in weak Z layer bonding. It is more ideal to run smaller batches of small objects if strength is critical.
Avoid running a full bed of small parts if you want to maximize strength
The print profiles are designed to handle overhangs of 45° with very high thermal mass (thick walls/infill) without warping and good surface finish. This requires a generous amount of cooling that limits the strength potential of the parts. For models that have few or non demanding overhangs, cooling can be reduced to 10% for both PA-CF and PA-GF to maximize part strength.
For parts with demanding overhangs, the default slicer parameters provide adequate cooling. Here, 20% cooling is necessary to avoid edge curling.
This rocket tailfin was printed with only 10% cooling with good surface finish as the overhangs are much easier to print. The resulting part will be stronger due to reduced part cooling.
Cooling parameters can be modified in the filament settings → cooling → fan speed. Set min and max to be the same value.