The mutual position accuracy of each component, such as coaxiality, parallelism, verticality, etc. ; Relative motion accuracy, such as transmission accuracy, linear motion and rotary motion accuracy; Fit accuracy and contact accuracy, such as fit clearance, interference, contact condition, etc. ; The wall thickness of plastic molded parts is uniform and large. When the new mold is positioned, the wall thickness of the molded part should deviate from the lower limit of the size.