Optimizing Dyeing Vessel Liquor Ratios for Fabric Quality
Optimizing liquor ratios requires balancing steam and salt savings against pump turnover rates to prevent severe shade unlevelness and mechanical creasing.
Running Creases
Defect Mechanism
Wet processing in rope-form dyeing machines can generate permanent, linear fold marks along the length of the fabric roll when the material remains folded in the same position for extended periods. These running creases appear as long, irregular lines of lighter or darker color where the fabric rope was compressed and shielded from the dye liquor. This physical defect occurs when the fabric is folded under high pressure and temperature, which locks the crease into the yarn structure.
Machine Parameters
Friction and fabric speed within the machine storage chamber directly influence the severity of the crease formation. If the running creases are caused by the fabric rope sliding too slowly or stalling in the j-box, technicians must increase the pump pressure or adjust the plaiter speed to keep the fabric moving continuously. This speed adjustment ensures that the fabric rope folds in different positions during each circulation, preventing the same fold from being compressed repeatedly in the high-temperature zones, which helps maintain a uniform surface appearance across the entire length of the fabric roll.
Prevention Method
Chemical auxiliaries and mechanical adjustments are used to reduce the risk of fabric folding during the dyeing cycle. Adding lubricating agents to the dye bath helps the fabric rope slide smoothly over itself and the metal surfaces of the machine, which reduces the friction that causes fold compression. These lubricants are essential when processing delicate knitwear and heavyweight fabrics, which are highly susceptible to running creases due to their weight and bulk.
Finishing Solution
Correcting crease defects after they have occurred requires heat-setting or mechanical open-width finishing treatments. If the running creases are not too severe, they can sometimes be removed by re-running the fabric through a stenter frame under high tension and temperature to relax the yarns. This corrective step adds to the production cost and must be avoided by maintaining tight control over the dyeing process parameters.
Influence of Warp Cover Factor on Dye Circulation in Jet Processing
High warp cover factors reduce fabric liquid permeability, requiring wider rectangular nozzles and slower heating ramps to prevent surface shade unlevelness.