Break Draft Optimisation
topic
Break draft (back zone draft) of 1.1–1.5 opens the twist in the incoming roving to prepare fibres for main drafting. Too high (>1.8) causes fibre rupture in the back zone, generating thick places; too low (<1.05) fails to open roving twist, causing uneven main drafting. Optimum break draft depends on roving twist factor: higher roving TF requires higher break draft. For fine counts (>40 Ne), break draft must be carefully controlled to avoid adding to already-high main draft requirements.
Role
Break draft setting is a frequently misunderstood process variable that accounts for a significant share of drafting-related imperfections. An incorrectly set break draft produces imperfections that are indistinguishable on the Uster Tester from main-zone faults, leading engineers to investigate the wrong zone. Understanding the diagnostic distinction between back-zone and main-zone faults saves hours of troubleshooting time.