Air-Jet Loom

Overview

An air-jet loom is the fastest weft-insertion weaving machine in volume production. Instead of carrying the weft through the shed on a shuttle or a mechanical arm, it blows the yarn across on jets of compressed air. With nothing solid crossing the warp, the insertion can run far faster than a rapier or projectile loom, which makes air-jet looms the standard choice for high-volume plain and dobby fabrics: shirtings, sheetings, denim and technical cloth.

The trade-off is that air is hard to control over a wide loom. A single jet would lose its grip on the yarn within a few hundred millimetres, so the machine uses a relay of nozzles set in a channel formed by the reed, each firing in turn to keep the weft tip moving and straight across the full width. The whole sequence happens in a few milliseconds and repeats up to twenty-five times a second.

How it works

For each pick the Heald Frames & Shedding motion lifts the heald frames, carried by a cam or dobby and driven by servo motors, to open a clean shed. Then the Air Weft Insertion takes over: a main nozzle grips the weft tip from a measured length held by an accumulator and launches it into the shed, while the relay nozzles set along the reed channel fire one after another to relay the yarn to the far selvedge. Air tanks store the pressure for a sharp blast and fast solenoid valves, switched by relays, open each nozzle only for the microseconds the weft passes it.

A weft sensor at the far edge confirms arrival and stops the loom if the pick failed. The Reed & Sley then swings its crank-driven sley so the profile reed, whose dents both guide the jet and pack the cloth, beats the new pick up to the fell. Warp is fed by the servo Warp Beam & Let-Off at controlled tension and finished cloth is drawn off and wound by the Cloth Take-Up. The Loom Control times every nozzle valve, shed and beat-up to the main-shaft encoder so the air, the warp and the reed all meet at the right instant.