Autoleveller Draw Frames Short and Long Term
topic
Short-term autolevellers measure sliver mass entering the main drafting zone using a sensing element between break and main draft, applying immediate correction to the main draft ratio through servo-controlled bottom roller speed changes within 0.1 seconds, while long-term systems measure delivered sliver mass and apply slower corrections maintaining delivery count within plus or minus 0.5 percent coefficient of variation.
Role
Establishes the sliver count accuracy at the drawing stage that directly determines yarn count CV percent in ring spinning, with short-term levelling correcting medium wavelength mass variations from card autoleveller imperfections and long-term levelling maintaining absolute count against production speed changes and raw material density variations throughout multi-hour production runs.