Sunday, September 29, 2019

LET - OFF MOTION ( SECONDARY LOOM MOTION)

LET - OFF MOTION:


Let - off motion is a secondary loom motion. The main objectives of let - off motion are to release the warp after beating of every inserted pick and to regulate the warp tension. When the fabric weaving remains continue, the take- up motion pulls the woven fabric continuously to maintain the fell of the cloth position. The warp tension gets increased due to continuous fabric pulling in the absence of let - off motion. The ends get broken after few loom revolutions. The continuous weaving process dose not get possible without let - off motion. Thus we can say that " A suitable mechanism which releases the warp after beating of every inserted pick and regulates warp tension during fabric weaving is called let - off motion". Various kinds of let - off mechanism are used in different looms. Today's loom is equipped with electronic let off motion. A load cell is mounted on  one  back rest roll. The warp sheet passes over this roll. When the tension increases or decreases, the load cell reads the actual warp tension. A servo motor and a train of wheels is also attached to warp beam. The load cell sends warp tension readings continuously to the loom control system. This control system process the data and releases the command to let - off motor simultaneously. The servo motor releases the warp sheet according to tension setting in loom control system. 

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