Print warping is probably the most frustrating issue we will encounter in our printing activities. The damage done by warping can ruin the precision of a model. It can be so severe that the print will curl and catch on the hot end's nozzle, lifting the entire print off the bed.
Print warping is caused by a difference in print temperature and shrinkage along the z axis. This is notably apparent when using ABS filament. ABS cools and shrinks quickly in comparison to PLA. Both can develop warping issues, but ABS is the more problematic of the two.
See Appendix C, Filament Options for RepRap Printers, for more information about different filament materials.
The following image demonstrates this by showing two test runs. ...