Latch Needle Design and Function
topic
Latch needles use a pivoting latch that swings open during yarn feeding to allow the new loop to form over the hook and closed by the old loop riding up the needle stem during casting off, with latch geometry including latch length, hook curvature, and stem taper determining loop size consistency and needle reliability at defined yarn counts and machine speeds in circular and flat weft knitting applications.
Role
Performs the fundamental loop formation operation in weft knitting through the self-acting latch mechanism that requires no external control element to open and close during the knitting cycle, with latch needle simplicity enabling the very high machine speeds and high needle counts of modern circular knitting machines while latch condition being the primary needle failure mode requiring replacement when latch becomes stiff or damaged.