Shed Opening Timing and Dwell Angle
topic
Shed opening timing defines the crank angle at which the shed reaches full open position relative to weft insertion, with early shedding completing full opening before weft insertion begins for maximum dwell time and insertion reliability, while late shedding delays full opening to reduce simultaneous shedding and beat-up force stress on warp ends, with dwell angle being the crank angle range during which the shed remains fully open for weft insertion, typically 120 to 180 degrees for standard looms.
Role
Controls the time available for weft insertion within the open shed and the mechanical stress on warp ends from the simultaneous action of shedding and beat-up forces, with shed timing optimisation being a critical setup parameter particularly at high weaving speeds where the available time for each event decreases and where the timing relationship between shedding and insertion must be precisely maintained to prevent the timing-related insertion failures and warp breaks that occur when events overlap incorrectly.