Drying filaments before processing
Drying is important for the stabilization of the quality of every printed object (without the influence of storage conditions). The material may absorb moisture due to storage out of sachet or after a long time of printing when the spool is in the room. Some polymers absorb moisture only on its surface, but hygroscopic materials absorb it into the whole structure. Therefore, the materials were divided into scale 1–5 (1 – not necessary to dry, 5 – always needed). See column “The need to dry” in the table.
Processing of moist hygroscopic materials at melting temperature causes that the water molecules attack polymer chains, which are irreversibly shortened.
The filament must be dried in the device with exact thermoregulation (ideally laboratory dryer) – before drying of the whole spool, put a little piece of filament into the device for the test of functionality. In the case that the material becomes softer or looses its original shape, lower the temperature of drying. In the case of loss of transparency, use a different device.
The spool can’t be put into the environment without a controlled value of relative humidity after drying. The cooling process must be taken in the desiccator (or in the sealing box with the content of silica gel). If the hot spool is placed into the environment with higher humidity, the moisture may be absorbed back in about 10 minutes. And possibly on a higher level of moisture than it was before drying!
The moisture content in the material influences final properties, the polymer chains are cut and therefore:
- Especially mechanical properties get worst (= MP), the material becomes more brittle, eventually more flexible
- Stringing occurs a lot (fine hair when moving the nozzle)
- Temperature and chemical resistance decrease
- Layer adhesion gets worst, the entirety of the printed object is violated
- Oozing occurs (accumulation of material on the side of the nozzle, which may lead to release and contamination of object), · the nozzle can be clogged because of the accumulation of degraded material
|MATERIAL||MIN. TIME OF DRYING||TEMPERATURE OF DRYING||THE NEED TO DRY||THE CONTENT OF MOISTURE CAUSES|
|ABS EXTRAFILL||2 h||80 °C||2||Process stability|
Process stability, low layer adhesion in case of colour Metallic Grey
|CPE CF112 CARBON||5 h||75 °C||5||Stringing, MP, oozing|
|CPE HG100||5 h||75 °C||5||Stringing, MP, temperature and chemical resistance, bubbles, „foamy“ appearance of printed object|
|FLEXFILL TPE 90A||2 h||80 °C||2||/|
|FLEXFILL TPE 96A||2 h||80 °C||2||/|
|FLEXFILL TPU 92A||3 h||80 °C||5||Stringing, low layer adhesion, clogged nozzle|
|FLEXFILL TPU 98A||3 h||100 °C||5||Stringing, low layer adhesion, clogged nozzle|
|HIPS EXTRAFILL||3 h||70 °C||1||/|
|NYLON AF80 ARAMID||4 h||80 °C||5||MP, colour change|
|NYLON CF15 CARBON||4 h||80 °C||5||Stringing, MP|
|NYLON FX256||3 h||80 °C||5||Stringing, MP, bubbles|
|PC/ABS||4 h||80 °C||5||Stringing, MP, appearance of surface|
*for now only in USA eshop
|4 h||65 °C||5||
Stringing, MP, bubbles, sputtering, “foamy appearance”, under-extrusion
|PLA CRYSTAL CLEAR||4 h||50 °C||5||Stringing, MP, clogged nozzle, optical clarity|
|PLA EXTRAFILL||3 h||50 °C||5||Stringing, MP|
|PP 2320||2 h||80 °C||1||/|
|TIMBERFILL||2 h||50 °C||5||Stringing, MP|
|VINYL 303||2 h||70 °C||1||/|