Cotton Ginning

Cotton ginning separates lint fibres from seeds, leaf trash, and stem material in seed cotton harvested at 20–25% moisture and cleaned to 10–12% before ginning. Two gin types dominate: saw gin (upland cotton, 40–50 circular saws at 500–600 rpm cutting fibres from seeds at throughput of 10–15 bales/hour) and roller gin (ELS cotton, leather or synthetic rollers at 300–400 rpm preserving fibre length at throughput of 1–3 bales/hour). Lint turnout (lint percentage) is 38–44% for upland and 32–38% for ELS varieties. Seed cotton passes through pre-cleaner (drum cleaner, 300–500 rpm), stick machine, and extractor-feeder before the gin stand. Post-gin lint cleaner (saw-type, 1–2 passes) removes remaining trash to achieve grade. Over-ginning causes fibre shortening (UHML reduction of 0.5–2 mm per extra gin saw passage) and nep generation (5–15 neps/g increase per pass).