Stretching Approach

4

StretchingApproach

StretchingApproach

Thedemand for wool in the market can be increased using two keystrategies. First, the stakeholders in the textile industry canincrease the number of fine yarn products that are offered in themarket. Secondly, some modifications (such as the alternation of thedegree of cluster) on the surface appearance may increase the demand.Under traditional methods, manufacturers have been using fine woolswith a diameter of less than 18 microns in order to facilitate theproduction of fine yarn apparels. They have been using additionalchemicals to enhance the surface appearance. The application ofchemicals has been considered as derivative approach and it oftenresults in the loss of substantial material. Although the thinness ofthe material can be achieved using chemicals, it is estimated thatits decrease by one micron accounts for up 10 % loss of fiber.

Stretchingthe material is currently considered as an alternative approach. Amaterial that is stretched can undergo a decrease in its diameterdown to 18 microns. Unfortunately, the stretching approach hasremained a theory since the stakeholders are yet to device practicalmechanisms. Previous attempts have shown that stretching of fiberrequires the application of special machinery, which could beuneconomical. Successful stretching is achieved when the fiber isgripped at the intervals of approximately 50-70 mm or continuously.The process of gripping ensures that the residence time that issufficient to facilitate stretching is achieved.

TheBritish patent number 1,189,994 provided an example of the fiberstretching approach. Under this technique, the untwisted assembly offiber is made to pass through a unique array of grip devices that arealternately oppositely and laterally moving. These grip devices areplaced a distance of between 50 mm and 70 mm. However, a treatmentmachine with a length of 30-40 m is needed in order to ensure that aresidence time that is adequate to facilitate a successful fiberstretching has been achieved. Kim etal.explained another technique in the Textile Research Journal. Thisexplanation was provided at 370 in June 1984 and at 325 in May of thesame year. It focused on the mechanization of the process that couldbe used to stretch the cotton fiber. The apparatus proposed by Kim etal.consisted of a set of drive rollers that were closely spaced. Theyhad a diameter that increased gradually. The apparatus had idlerrollers that were put on its top. The roving was allowed to pass overthe top rollers and under the bottom ones. Although the sameapparatus could be adapted to facilitate the stretching of wool,manufacturers would require a lot of rollers in order to attain therequired residence time for commercial production.

TheBritish patent number 1,196,419 made a proposal indicating that asliver could be stretched by inserting the twist into the staplefiber. Manufacturers can avoid drafting of the sliver and facilitatestretching of the target fiber because the twist raises the level offrictional engagement. The apparatus as well as the approach proposedby the patent required the application of devices that could help theprocessors insert the actual twists in the upstream of the stretcharrangement. This arrangement is comprised of two extending pairs ofrollers that are extended in the longitudinal manner. The twistedsliver is then twisted around the roller and passed through anuntwisting device that is located on the downstream side of thearrangement. A complex arrangement of machines is required in orderto achieve the correlation between the twist insertion and removalrates. The twist insertion and removal rates are always differentunder the arrangements proposed in the patent.

Difficultiesmay be experienced during the subsequent processing steps, especiallywhen the twist is not accurate. Inaccurate twisting results inresidual errors that cause the difficulties experienced in thesubsequent phases of the fiber processing. Processors may also limitthe apparatus to the batch mode during the insertion of real twist.This occurrence is attributed to the fact that the wound assembly andthe supply of ball of the fiber at the input point should be rotatedin order to facilitate the insertion of the twist. The need toprovide a fresh wound assembly or the supply ball limits the level ofproductivity for the subsequent round once the current sliver hasbeen unwound. The automation of this type of batch processing isquite conceivable, but it would require the application of morecomplex machinery, especially at the input point. This heavyinvestment would limit the commercial viability of the overallprocess.

TheU.S. patent number 5,477,669 indicated that the natural fiber couldbe stretched in order to achieve the desired level of reduction inthe size of the diameter. This stretching is achieved through aseries of steps. Untwisted natural fiber is treated in order toplasticize it. The treated fiber is then twisted in a manner thatreduces the chances for drafting during the subsequent process ofstretching. The untwisted fiber is then warped successfully. Some ofthe key achievements made include an increase in the length, adecline in size of the diameter, and the modification of luster.However, this arrangement was not complex, which resulted in thedamaging of the surface of the fiber, wetting of modulus, and theloss of wool.

Breeding

Improvementof the superfine fiber (including the wool and cashmere) can beachieved through genetic approaches (Li etal.,2010). Studies conducted by Zhou etal.(2002, 2003) focused on genetic parameters and non-genetic effectsthat occur during the production of different traits of IMC. Anothergroup of researchers, Bai etal.(2004, 2006) provided a model that is considered to be appropriatefor the growth of traits at an early stage. The model compared thelevels of accuracy of various frameworks and analyzed genetic trends(such as the body weight and cashmere production) that were linked toIMC. A study conducted on the Australian cashmere goats indicatedthat the length of the fiber could be affected by the age of theanimal (McGregor and Butler, 2008). The IMCGs have a higher FL (10.51cm) compared to Australian cashmere goats that have a value of 8.7cm. The differences could be attributed to variations in terms ofclimate, breed, feeding, and firm management practices. A combinationof IMCGs body weight and fiber yield enhanced genetic as well as thephenotype of the fiber, but it became coarser.

Astudy conducted by Wang etal.(2012) indicated that the heritability of the qualities of the fibershould be considered as moderate. Huisman and Brown (2009) and Brashetal.(1997) managed to show that estimates of different genetic parametersfor sheep’s wool were different at various ages, including adult,hogget, and yearlings. A study conducted by Fozi etal.(2012) indicated that the mean diameter of the fiber could providethe fine wool data that is partitioned into 3 years, 2 years,yearling, and later ages. The medium wool data could be classifiedinto 2 years, hogget, and later ages using the multivariate mode. Theaverage price of coarse cashmere is lower than that of fine fiber.

Cashmerecan be classified as B diameter following an increase in its diameterto between 14.0 and 16.0 µm. This increase results in a 40 %discount compared to cashmere in the A diameter class. The length ofthe fiber is expected to be at least 5 cm in order to facilitate theconversion of cashmere to the final yarn (Maet al.,2008). The length influences the processing of cashmere while thefiber’s diameter affects the aspect of softness. Softness improvesthe comfort of the wearers of the final apparel. Herdsmen benefitfrom genetic improvement that is achieved in terms of diameter andthe length of the fiber. A positive correlation that exists betweenFD and FL has been found to be unfavorable during the selection ofhigh superfine fibers. The positive correlations of the breedingvalues for FD and FL between two age groups were positive. However,the process of enhancing the quality of fiber through genetic meansis expensive and consumes a lot of time.