faults & remedies/preventive measures in knitted fabric dyeing
TRANSCRIPT
SOUTHEAST UNIVERSITYDEPARTMENT OF TEXTILE ENGINEERING
KNIT DYEING FAULTS & REMEDIES
EXAMPLE OF DYEING FAULTS
Uneven dyeing.
Running shade.
Batch to batch shade variation.
Patchy dyeing effect.
Roll to roll variation or Meter to meter variation.
Crease / Wrinkle mark.
Dye spot.
Softener mark.
Fabric hole.
UNEVEN DYEING.
Causes:
• Uneven pretreatment (uneven scouring & bleaching).
• Improper color dosing.
Remedy:
• By ensuring even pretreatment.
• Proper dosing of dyes and chemicals.
Patchy dyeing effect.Causes:
• Faulty injection of alkali.
• Due to improper salt addition.
Remedy:
• Proper dosing of dyes and chemicals.
• Heat should be same throughout the dye liquor.
Roll to roll variation or Meter to Meter variation:Causes:
• Poor migration property of dyes.
• Improper dyes solubility
Remedies:
• Use standard dyes and chemicals.
• Proper m/c speed.
PATCHY DYEING EFFECT.
Causes:
• Faulty injection of alkali.
• Due to improper salt addition.
Remedy:
• Proper dosing of dyes and chemicals.
• Heat should be same throughout the dye liquor.
ROLL TO ROLL VARIATION OR METER TO METER
VARIATION:
Causes:
• Poor migration
property of dyes.
• Improper dyes
solubility
Remedies:
• Use standard dyes
and chemicals.
• Proper m/c speed.
BATCH TO BATCH SHADE VARIATION
Causes:
Shade variation can be as a result of mixing of the fabrics of two different lots.
Shade variation is also caused by the variation in the process parameters i.e. Time, Temperature & Speed etc. from one fabric roll, to the other.
CONT...
Remedies:
Ensure that the grey fabric used for one shade is
knitted from the same lot of the yarn.
Ensure that the same process parameters (Width,
Overfeed, Temperature & Machine Speed etc.)
are used, for each roll of a dye lot.
SOFTENER MARK:
Causes:
• Improper mixing of the Softener.
• Improper running time of the fabric during
application of softener.
Remedies:
• Maintaining proper reel sped & pump speed.
• Proper Mixing of the softener before addition.
FABRIC HOLE.
causes:
• More acid of knit
fabric in the dyeing
section.
• Temperature highly.
Remedy:
• Use standard Acid.
• Proper dosing of
Acid.
PIN HOLE DAMAGE:
Causes: Oxidation of the knitting
oil/lubricant on the fabric stored for a long duration.
Presence of sharp metallic part in some parts of machine
Presence of heavy metal ions in peroxide bath.
Remedies: Check presence of any
sharp object in machine Provide magnetic filters in
water/ steam line
CREASE MARK:
Causes: More cycle time. Faulty plaiting device. Slack on tight selvedge causes
creases at an angle to each selvedge.
Incorrectly set bowed-expander. Variation of heating and cooling
rate. Improper fabric movement.
Remedy: Anti- creasing agents are used to
avoid crease mark problem.
DYE SPOTS
Causes:
These are most often caused by operators not correctly mixing and thoroughly dissolving the dyestuff, in the right amount of water.
Dye bath hardness.
Not agitation of dyestuff.
Remedies:
Use adequate amount sequestrate to lower bath hardness.
Proper agitation.