In the case of center winding (also known as overhanging winding), it may be because the winding tension is set too high.

If it is surface center winding (also known as press type winding), it may be because the pressure setting is too high.

Of course, it is also possible that you in the unwinding and stretching process of the tension or film threading method is not adjusted properly, resulting in film wrinkles, or may be the unwinding of the film itself has been wrinkled and has formed a dead wrinkle!