Evaluating Linear Density Uniformity in Wet Spun Flax Sliver Lots
Evaluating wet-spun flax sliver linear density requires combining ten-metre cut-and-weigh gravimetric tests with conditioned capacitance spectrogram analysis.
Autoleveler Response Lag
Delay Metric
Closed-loop mechanical delay during sliver attenuation represents the temporal interval between thickness detection at the measuring rollers and physical draft adjustment at the drafting zone. This delay, defined as autoleveler response lag, determines how quickly an open-end or draw frame drafting system corrects mass variations in flax sliver. The boundary of this measurement covers active mechanical draw frames operating in wet spinning preparation and excludes manual draft gear adjustments.
Control Mechanism
Detection wheels monitor sliver volume in real time and transfer signal voltage to a central processing unit that calculates required servo motor speed changes. Physical inertia in the drafting motor and drive belts delays the actual speed adjustment, creating a transient period where uncorrected sliver passes through the roller nip. When delivery speed increases, the physical length of uncorrected material expands proportionately.
Signal filtration algorithms reduce false triggers from surface fiber hairs while maintaining response times under fifteen milliseconds.
Quality Consequence
Excessive delay during drafting creates periodic thick and thin places that persist through roving and wet spinning stages. These periodic variations generate periodic mass spikes visible on spectrograms at wavelengths matching the distance between the measuring point and the drafting zone. Mill quality standards mandate response thresholds below ten milliseconds for high-count yarn production.
Uncorrected mass variations increase yarn breakage rates during wet spinning on ring frames and cause irregular dye absorption during fabric finishing.