CRABBING AND OBJECT OF CRABBING

Crabbing of wool, object of wool crabbing,method of crabbing, parameter of crabbing,what is wool crabbing,wool crabbing processes,

wool crabbing

OBJECT OF CRABBING

Crabbing is a setting process of wool. It is carried out to bring dimensional Stability. To eliminate the latent strains developed on the fibre during spinning and weaving. To eliminate the distort tins like crocking, crows foot patterns and uneven shrinkage. The degree of stress relaxation during crabbing depends on: t) The fibre quality Yarn twist  Cloth cons traction Subsequent dyeing and finishing operations. It is important for the finishing of fabric containing 1 Mohair or cross bred wool .Light weight open weave fabric. dial twisted vary containing fairies


METHOD


Essentially, crabbing consists of winding the fabric on a roller under tension on to a beam through Hot or Boiling water containing a Wetting agent and then rotating the loaded beam in the hot or boiling bath for about 10 mins The fabric is turn wound on another beam and the operation is repeated By this method, the fabric is set and does not get distorted during the subsequent processing.


PARAMETERS


The effectiveness of crabbing depends on, ) The tension. e) Duration of treatment. 3) Composition of crabbing liquor Temperature. pH of the crabbing liquor. The tension should be uniform. Higher tension leads to the production of a Papery Feel in the fabric The temperature must be constant Too low temperature leads to and seaquake setting The pH of the crabbing liquor should be maintained at 7. Poor setting may take place if the pH becu.nes acidic In the composition of the crabbing 1quor no alkali should be added The addition 1 of alkali will damage the cloth



Prolonged crabbing with alkaline solution discolor the fabric and impart a poor handle. Care should be taken while winding, as bad winding leads to Listing. Crease should not be allowed to form while winding. as these creases too will get set during crabbing.


In the simplest crabbing machine, the fabric wound on a roller is unwound, passed around guide rollers into hot or boiling water and wound back on a roller A weighting roller on the top ensures that the pressure is applied during the winding onto the lower roller.



The roller is allowed to rotate till the water is cooled at room temperature. Crabbing of woo!len fabrics is based on the combined effect of moisture and heat on the fabrics. It is repeated for several times to achieve permanent setting of wool


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