Glossary
Warping
Warping is corners or edges lifting off the bed as plastic cools and shrinks unevenly, common with ABS printed without an enclosure.
Warping happens when the bottom of a print cools and contracts faster than the rest of the part, pulling corners and edges up off the build plate instead of letting them stay flat. It is most common on materials that shrink noticeably as they cool, such as ABS, and on parts with large flat bases or sharp corners that concentrate stress in one spot.
Warping is less about the plastic being defective and more about temperature control across the whole print. A cold draft across one side of the printer, an unheated room, or a bed that loses heat unevenly can all make one corner lift before the rest of the layer has a chance to bond down properly.
Reducing warping usually means keeping the surrounding air warm and still, which is where an enclosed printer helps a lot with ABS and similar materials, along with strong first layer adhesion and sometimes a brim around the base of the model. A common mistake is chasing bed temperature alone while ignoring drafts from an open window or a fan blowing across the printer.