While printing with recycled PLA we experienced considerable expansion and shrinkage of material. Since PLA is an amorphous plastic it shown behavior is to form freely, which results in the shrinkage and warping after extrusion. Lowering the extrusion temperature and directly applying cooled airflow improved the results.
Printing settings Temperature: 170 – 180 °C Printspeed: 20 mm/s Printlayer: 5 – 8 mm
In addition the forming of air bubbles amplified the expanding and shrinking process. PLA is known for being hydroscopic and is able to absorb up to 4% of its weight in water. When heating up the water vaporizes, resulting in the forming of air bubbles. Dry storage and being able to dehydrate the material before use is essential for quality production with PLA.