Precision plastic gear errors are classified according to the use of the performance of gear, generally can be divided into three kinds:            1.Kinematic accuracy; cumulative error such as pitch, is used to measure the precision gear in a circle movement, the maximum amplitude of actual precision gear angle, used to accurately evaluate the extent of the gears transmission. Belongs to the long period error.                          2.Dynamic accuracy; such as tooth profile error, is used to measure the precision gear in a gear motor, the maximum amplitude of fluctuation of the actual precision gear angle, fluctuation degree is used to evaluate the precision gear to rotate speed, or the size of acceleration. Belongs to the short period error.
3.The contact accuracy; such as a tooth contact pattern along the tooth height and width in the whole tooth surface position, shape and size. In addition to the above several accuracy, and the gear side clearance and other error.