Thermal Fixation Dwell Time Calibration for Micro Polyamide Spandex Knits
Calibrate stenter line speed to effective core dwell time above 190°C rather than total chamber residence to prevent spandex degradation and knit shrinkage.
Overfeed Calibration
Tension Regulation
Adjusting the ratio between the feed-in speed and the take-up speed of a fabric processing machine controls the tension of the moving web. Proper overfeed calibration allows the textile material to be fed into a stenter frame or compactor at a rate faster than it is pulled out. This extra length allows the fabric loops to relax and shrink within the drying chamber.
Without this adjustment, knit fabrics will retain high residual shrinkage, leading to garment distortion after washing.
Dimensional Control
Feeding fabric with a positive speed differential relaxes the internal stresses built up during knitting and dyeing. In circular knit finishing, correct overfeed calibration ensures that the fabric length shrinkage does not exceed five percent in subsequent home launderings. The process involves coordinating the speeds of the entry rollers and the pin chains on the stenter frame.
This mechanical control is the primary tool for adjusting fabric weight and yield.
Process Optimization
Industrial finishing lines must adapt this speed ratio for each fabric construction to achieve the target weight per square meter. A heavy fleece requires a higher percentage of overfeed to allow the fabric to shrink and bulk, whereas a stable woven fabric requires very little. Incorrect calibration can result in either excessive bulkiness and fabric sagging or high tension and narrow fabric widths.
Finishing operators use digital control panels to monitor and adjust these ratios in real time.
Quality Verification
Consistent calibration of the feeding system prevents variance in fabric weight from the beginning to the end of the production batch. This precise tension management ensures that the finished roll matches the commercial fabric specification.