Doffing Process and Automation
topic
Doffing is the simultaneous removal of full cops and replacement with empty bobbins on all spindles of a frame, performed when cops reach full weight (60–120 g). Manual doffing requires 8–12 operators per frame and 15–20 minutes downtime; automatic doffing systems complete the process in 2–4 minutes with 1 operator supervising. The doffing cycle includes: speed reduction, simultaneous gripper extraction of full cops, empty bobbin placement, and restart. Doffing frequency depends on cop weight and production rate.
Role
Doffing efficiency directly determines machine utilisation — a 20-minute manual doff on a 50-minute cycle represents 28% downtime. Automatic doffing raises machine utilisation from 72% to 95%+, dramatically improving capital productivity. Understanding doffing mechanics and automation is essential for economic justification of ring frame investment in high-labour-cost countries.