In balanced force technique used for canal preparation:

Balanced force concept uses Flex-R file and is described as "Positioning and pre-loading an instrument through a clockwise rotation and then shaping the canal with a counterclockwise rotation".  Many authors discovered that greater risk of instrument damage was associated with clockwise movement.  For best results, preparation is completed in a step-down approach.  After mechanical shaping of coronal and middle thirds with Gates-Glidden drill, insertion of the instrument is done with a quarter turn clockwise rotation while slight apical pressure is applied.  Cutting is accomplished by making a "Counterclockwise rotation".  The counter-clockwise rotation and apical pressure act together to enlarge and shape the canal to the diameter of the instrument.  The clockwise rotation should not exceed 90° while the counterclockwise motion must be 120° degrees or greater.