Statistical Acceptance Sampling Plans for Cross-Web Chemical Variances
Cross-web chemical variances require three-point variable acceptance sampling to prevent edge-concentration hotspots from triggering border detentions.
Wet Pickup Profile
Liquid Absorption
Continuous wet processing measures chemical bath liquor mass absorbed by fabric relative to dry fabric weight during padding operations. The wet pickup profile records percentage liquor absorption at multiple points across the full width of the fabric web. Maintaining a uniform liquor uptake profile prevents widthwise variations in resin crosslinking, shade depth and functional finish performance.
Padder Mechanics
Foulard padder rolls squeeze liquid dye or finishing liquor into fabric pores under high pneumatic pressure. Deflection across long roller shafts causes uneven nip pressure, creating higher wet pickup in the middle or at the selvages. Technicians adjust crown rolls, roll pressure and liquor trough level to equalize squeeze force across the entire roll face.
Drying Impact
Variations in wet pickup profile force stenter frames to evaporate unequal water volumes across the fabric width. Over-drying low pickup zones while under-drying high pickup zones causes uneven resin curing, shade listing and fabric width distortion. Balanced liquid absorption ensures uniform moisture removal during thermal processing steps.
Quality Control
Beta-ray gauges or microwave moisture sensors measure wet pickup immediately after padder squeezing. Real-time feedback adjusts pneumatic roll pressure automatically to maintain a flat wet pickup profile across continuous dyeing runs.