TheEnds-Down of the Resultant Ring Spun Yarn from Constant True AnimalFibre
Spinningends-down is one of the crucial determinant factors of spinningmill’s cost and quality. Ends-down is a seldom-occurring event witha very slight probability of re-occurring. The ends-down and theefficiency of a spinning mill’s vary proportionally meaning thehigher the ends-down, the lower the efficiency in spinning, winding,weaving and excessive faults in fabric and the opposite is true.Through these factors, the standard ends-down rate in developedcountries is less than 50 per 1000 spindle hours. The typical ringspinning system configuration uses the yarn that issues from theroller nip and passes through the yarn guide that is around freerotate ring wounded onto a bobbin and mounted on a rotating spindle.
Thespindle uses a motor to run and therefore, making the yarn guide bedriven around the ring of the yarn loop. Each rotation produced bythe spindle inserts one twist into the yarn between the nip and thetraveller. The twist makes the yarn wound continuously onto thebobbin at the same rate the yarn is issuing from the roller nip.
Somefactors affect the rate of spinning ends-down. Primary factorsinclude the quality of roving, the draughting system, the twistingand winding system, the yarn count and twist, the piecing duringdrawing and lastly, the machine maintenance and mill conditions. Fora well-maintained mill with optimum machine settings, the causes ofends-down are limited since the mechanism of ends-down solely dependson the relative magnitudes of the strength and spinning tension ofthe yarn. This means that if the spinning tension of the yard exceedsthe power of the yarn end-down occurs. This is because the spinningtension and strength of the yarn vary with the time of ends-down. Theends-down can be predicted in a spinning yard if only one uses a goodyarn strength predictor model that have a clear understanding of themechanisms of spinning tension.
Thestrength of the static yarn strength is measured on the bobbin in themodel after very spin. However, the power of the yarn differs fromeach spin this is because the twist of the yarn is not always fixedin the zone where the fibres and the front rollers emerge. In casethe yarn strength is weaker, it is referred as dynamic strength.Dynamic strength is caused by a lower twist that occurs due to lowstrength of the end-down spin and is primarily determined by thestatic yarn strength. The ratio of dynamic strength, which also referas dynamic strength efficiency depends on three primary factors. Thefactors are the spinning speed, twist and fibre length. The rate ofspinning and twist varies proportional to the dynamic strength,meaning that an increase in velocity and twist of the yarn reducesthe dynamic strength. The pressure on the roller also has an effecton the dynamic strength, a decrease in pressure in the roller leadsto decrease in dynamic strength. In relation to the dynamic strength,the rate of extension may also affect the strength of the wool andthe static strength.
Spinningtension is derived from winding tension force its primary functionis in the winding speed, the traveller mass, ring size, windingangle, and the yarn linear density. The main source of the windingtension is from the friction between the traveller and the ringtension is a necessity for efficient production of a from bobbinpackage. Air drag plays a significant role in ring spinning, althoughthe effect of the traveller ring friction is small. The effect of airdrag is that an increase in air drag allows the traveller ringfriction to reduce and in return to reduce the wear and tear of thering. To determine that the air drag is the maximum balloon radius,equations have been developed to explain this. For instance, thespinning tension varies periodically with time. However, this maychange depending on some factors such as the height of the balloon,the package radius, spindle vibration and the spindle speed.
Twoprimary factors, which are the spinning speed and the yarn Tex.determine tension size. This is because the ends-down happen onlywhen the tension is greater than the yarn strength, this means thatlarger tensional variation will cause higher ends-downs and viceversa are true that smaller tensional variation will cause lowerends-down. This, therefore, shows that the tension variation isnecessary for the rate of ends-down. As mentioned earlier that,ends-down is a seldom-occurring activity with a subtle probability ofreoccurring, the likelihood of reoccurring is 10-5 per yarn segment.This probability of reoccurring is determined by the strength of theyarn, spinning tension and variation, therefore, with thosedeterminers, the probability of ends-down can be determined. Inconnection with the fact that ends-down can be determined bycomparing the relative magnitude yarn of dynamic strength and tensionP, which is probability, can be expressed regarding functions x1 andx2.
Theabove explanation means that the probability of ends-down is a simplematter of calculating the rate of ends-down and as mentioned earliera yarn is a series of fracture zones, the fracture zone can beexpressed regarding f which is frequency. According to the Yarn specformula that states that frequency f is inversely proportional to thefracture zone L and proportional to the yarn delivery speed v and. This can be expressed in equation form of f=v/L. Where L=H.
Theuse of Yarn spec algorithms have now been validated and are nowextensively used in commercial mills. This has abandoned the use ofCSIRO’S algorithms commercial mills. Now with the use of Yarn specalgorithms, the effect of wool fibre properties and spinningparameters in ends-down can be demonstrated. The Yarn spec algorithmsexplain that a decrease in fibre length leads to a quick increase ofends-down, this explains why short fibre have a more significanteffect at the end as compared to a long fibre. For instance, if thefibre length is less than sixty-five mm (65mm) the spinning ends-downwill increase rapidly and if the fibre length is more than 65mm thespinning ends-down will decrease rapidly.
Thesecond effect of fibre length is on yarn twist. If the length of thefibre is small, this will cause high twist and vice versa are rightthat if the length is large, this will cause low twist. In connectionwith this increase in the twist of the yarn and decrease in length ofthe yarn, the ends down are predicted to increase and vice versa istrue. For instance, if the twist (α) of fibre is 90 yarns and thelength decreases from 65mm to 55 mm the ends-down are predicted toincrease by about 52%. However, if the twist is 70 yarns and thefibre is reduced at the same length, there is a possible increase ofestimated 150% of the ends-down. Lastly, bundle tenacity also has asignificant effect on ends-down. A decrease in bundle tenacity leadsto an increase in ends-down and the impact of tenacity is higher atlow tenacities than on shorter hauteur.