Comparison of the Cost Performance between Pure Cashmere Siro-spun Yarn and Pure Rabbit Hair Ring-spun Yarn

Yueling Liua,Bukun Sunb

Taiyuan University of Technology, jinzhong, shanxi, 030600, China

aszl_ly@126.com,bsunbukun6310@sina.com

Keywords:Cost performance ratio;Cashmere; Rabbit hair; Analytic hierarchy process (AHP); Siro-spun yarn; Ring-spun yarn; Yarn evenness;Yarn strength; Yarn hairiness; Wearing resistance

Abstract:This paper systematically analysied and measured the main properties of the pure cashmere

siro-spun yarn and pure rabbit hair ring-spun yarn, including the yarn evenness, thin and thick , neps,

raw material nature, yarn strength, yarn hairiness, twist level, wearing resistance and etc. And the

market price of yarn was also investigated. The model of the cost performance ratio was established

to analyse the yarn properties scientifically. The results indicated that the pure rabbit hair yarn is

better than the pure cashmere yarn. It provided the guidance suggestions and scientific basis for the

manufacturers to improve the performance and reduce the cost price of the yarn.

Introduction

With the gradual perfection of the high-grade textile market, 20.8 tex×2 pure cashmere yarn and pure

rabbit hair yarn are more requested in the textile market. Cost performance ratio is an important index

of evaluating the commodities, However , there is few research on the cost performance of the

textiles. This article deals with value engineering theory to build the cost performance model of

textiles. The model provides quantitative measurement and references for consumers and

manufacturers.

Establishment of the cost performance model of yarn

The cost performance model of yarn is based on the value engineering theory. The model can be

described as ARP=A/P. Then the cost performance ratio index (APRI) can be defined as a/p where a

stand for the performance index and p stand for the price index.

1.Definition of performance index

Table1 showed that A1,A2, … ,A8 represented the evaluating indicators including yarn evenness, thin

and thick , neps, raw material nature, yarn strength, yarn hairiness, twist level, wearing resistance. In

accordance with the use of the yarn (knitted yarn), they were analysed and compared pairwise, then

the judging matrix A can be obtained from Table 1.

Table1 The judging matrix A A1 A2 A3 A4 A5 A6 A7 A8

A1 1 2 2 6 3 5 6 4

A2 1/2 1 1 4 2 4 5 3

A3 1/2 1 1 4 2 4 5 3

A4 1/6 1/4 1/4 1 1/3 1/2 2 1/3

A5 1/3 1/2 1/2 3 1 1/3 3 2

A6 1/5 1/4 1/4 2 3 1 2 1/2

A7 1/6 1/5 1/5 1/2 1/3 1/2 1 1/3

A8 1/4 1/3 1/3 3 1/2 2 3 1

(1) Calculating the geometric means of the elements aij in each row of the judging matrix.

nij

n

ji αβ

1=

∏= ( )821= ,,,i …

(2)Normalizing the vector ( )T821 ,,, ββββ …= , then obtain the eigenvector

( )TW,,W,WW 821= …

∑1=

=

n

k

kii ββW ( )8,,2,1 …=i

Advanced Materials Research Vol. 331 (2011) pp 40-43Online available since 2011/Sep/02 at www.scientific.net© (2011) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.331.40

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(3)Calculating the maximum latent root λmax

( )∑

∑

∑1=

1=

1=

max

1=

×1=

n

k i

n

i

jijn

k i

i

W

Wα

nW

WA

nλ ( )8,,2,1 …=i

(4)Consistency check

( ) 411×7

8-=

1-

-==

.

λ

RIn

nλ

RI

CICR

maxmax

The values were substituted into the formula to get the weight coefficient

( ) ( )TT.,.,.,.,.,.,.,.W,,W,WW 10700700099011200760165016502060== 821 …

According to the expert system assistant decision-making comprehensive evaluation,the

performance index (by 100 score system counting ) could be obtained based on Uster Statistics. Then

all the scores given by experts were comprehensive analysed and eight evaluation index scores of the

yarn could be obtained. K1,K2,.....,K8 representrd eight evaluation index scores of the yarn.

Performance index of the yarn could be expressed as:

A=∑8

1=i

iiWK /∑8

1=i

iW

2.Definition of price index

The price index is a dimensionless number, hypothesize the yarn price is P0 when its performance

reach to the perfect score (perfect yarn), the price index P0 can be 0100 PPK × . P0 was obtained by the

expert system assistant decision-making comprehensive evaluation as well. [1]

3.Explanation of cost performance ratio index

The two-dimensional evaluation map (see as Fig.1) was illustrated according to the performance

index as abscissa and the price index as coordinate. Point A on the abscissa located the level of 75%

of the Uster Statistics. [2]

When the point that represented the performance index and the price index fell in zone A (see as

Fig.1), the cost performance index ratio is greater than 1 and it illustrated that the performance value

was greater than the sale price while the performance of the yarn was not ideal. When it fell in zone B,

the cost performance index ratio was greater than 1 and it indicated that the performance value was

greater than the sale price. The cost performance index ratio was less than 1 and the performance was

fine when it was in zone C. The cost performance index ratio was less than 1 and the sale price was

greater than the performance value when it was in zone D.

Comparison with the factors and analysis

Performance index analysis

1.1Raw material nature

The quality of the rabbit hair can be evaluated by the level of length, looseness, whiteness and

cleanliness. The average length of the top grade rabbit hair is 55.1mm or above, the one of the first

grade is 45.1mm or above, the one of the second grade is 35.1mm or above and the one of the third

grade is 25.1mm or above. In this experiment the length of the pure rabbit hair for ring-spun yarn was

42mm.

Advanced Materials Research Vol. 331 41

Cashmere is a kind of high-grade textile material which has a lot of advantages such as fineness,

evenness, softness, good elasticity, subdued luster and high strength. In this experiment the fineness

of the pure cashmere for siro-spun yarn is 15.20µm and the length is 28mm. [3]

The raw material nature indices are: pure cashmere: 70; pure rabbit hair: 90

1.2 Hairiness Table 2 Hairiness test results

Yarn species[unit of hairness] 3mm 4mm 5mm 6mm 7mm 8mm 9mm

Pure cashmere siro-spun yarn[Number / 10m] 109.66 29.00 3.66 2.00 0.66 0.00 0.00

Pure rabbit hair ring-spun yarn[Number / 10m] 207.66 103.33 33.00 20.33 7.33 4.00 2.33

The hairiness of the pure cashmere siro-spun yarn was obviously less than that of the pure rabbit hair

ring-spun yarn according to the result in Table 2. The two reasons of raw material and spinning

technology could explain the result. On one hand, the rabbit hair fibers had surface smooth and fiber

friction was small, so yarn hairiness was more. On the other hand, two roving that kept certain

interval were parallelly fed in the siro-spinning, after drawing, the front set of rollers output the two

single yarn, and because the twist can be transferred to each single yarn with small amounts of twist,

to combine two single yarn with twist into similar plied yarn, so hairiness are less in yarn.

The hairiness indices are: pure cashmere siro-spun yarn: 100, pure rabbit hair ring-spun yarn: 80.

1.3 Yarn strength Table3 Strength test results

Yarn species

Breaking

strength

[cN]

Stretchin

g

quantity

[mm]

Elongatio

n

[%]

Breaking

time

[s]

Breakin

g work

[N.m]

Breaking

tenacity

[cN/dtex]

Pure cashmere siro-spun yarn 250.9 42.49 8.46 18.24 0.080 0.601

Pure rabbit hair ring-spun yarn 340.7 96.58 19.28 21.09 0.243 0.816

The strength of the pure cashmere siro-spun yarn was obviously less than the pure rabbit hair

ring-spun yarn according to Table 3. First, in view of the fiber surface, the rabbit hair fibers were

smoother and fiber friction was smaller than those of cashmere. Second, in view of the fiber fineness,

the rabbit hair was finer considerably than that of cashmere. So the number of fibers in cross-section

of rabbit hair yarns was larger than that of cashmere yarn. Third, in view of the fiber length which

decided the cohesiveness, the rabbit hair fibers were longer than that of cashmere. At last,

siro-spinning technical increased the yam strength. By comprehensive analysis, it was known that

influence of the previous three factors is greater than the effect of technical aspects. So the strength of

the pure cashmere siro-spun yarn was obviously less than that of the pure rabbit hair ring-spun yarn. The yarn strength indices are: pure cashmere siro-spun yarn: 70,pure rabbit hair ring-spun yarn: 90.

1.4 Yarn evenness Table4 Evenness test results

Yarn species Coefficient of

variation{CV[%]}

-30%Thin

[number/200m]

+35%Thick

[number/200m]

+140%Neps

[number/200m]

Pure cashmere siro-spun yarn 10.54 79 14 47

Pure rabbit hair ring-spun yarn 9.62 14 10 50

Table 4 showed that the evenness coefficient of variability and nips and slubs of the pure cashmere

siro-spun yarn were more than that of the pure rabbit hair ring-spun yarn. This was mainly caused by

longer rabbit hair fibers and the obvious effect of process control. However the neps of the pure rabbit

hair ring-spun yarn were more than the pure cashmere siro-spun yarn, The reason was that rabbit hair

fibers were longer and tended to snarl into neps during the combing process. However, in general, the

both the two kinds of yarn have more neps than other kind..

According to the Uster Statistics and experiences, the yarn evenness indices were:

Pure cashmere siro-spun yarn: 90

Pure rabbit hair ring-spun yarn: 90

The thin and thick indices were:

Pure cashmere siro-spun yarn: 90

Pure rabbit hair ring-spun yarn: 90

42 Advances in Textile Engineering

The neps indices were:

Pure cashmere siro-spun yarn: 50

Pure rabbit hair ring-spun yarn: 50

1.5 Wearing resistance Table5 Wearing resistance test results

Yarn species Average

times[times]

CV[%]

Pure cashmere siro-spun yarn 209.1 11.17

Pure rabbit hair ring-spun yarn 181.7 10.44

The result inTable 5 indicated that the wearing resistance of the pure cashmere siro-spun yarn was

better than that of the pure rabbit hair ring-spun yarn. This was because cashmere fibers were thicker

and heavier and the siro-spun processing enhanced the wearing resistance.

According to the Uster Statistics and experiences, the wearing resistance indices were:

Pure cashmere siro-spun yarn: 80

Pure rabbit hair ring-spun yarn: 80

1.6 Twist level Table6 Twist level test results

Yarn species Average twist

[twist /25cm] CV[%]

Pure cashmere siro-spun yarn 99.6 8.51

Pure rabbit hair ring-spun yarn 102.8 7.42

In view of the fact that the yarn species are both knitted yarn, the twist levels of the yarn are basically

identical (see as Table6). The twist irregularity is mainly caused by the performance variance of the

machines.

According to the Uster Statistics and experiences, the twist level indices are:

Pure cashmere siro-spun yarn: 80

Pure rabbit hair ring-spun yarn: 80

2. Analysis of the price index

According to the expert analysis and market research, the market price of the perfect pure cashmere

siro-spun yarn was 700 yuan per kilogram, while the one of the perfect pure rabbit hair ring-spun yarn

was 300 yuan per kilogram. The market price of the pure cashmere yarn was 650 yuan per kilogram

and the pure rabbit hair yarn was 240 yuan per kilogram in the experiment.

3. Cost performance ratio

cashmere siro-spun yarn: 8495.0==p

aAPRI

rabbit hair ring-spun yarn: 0080.1==p

aAPRI

Conclusions

According to the cost performance ratio of the yarn, the point of the pure cashmere siro-spun yarn fell

in the zone C in Fig.1, while the point of the rabbit hair ring-spun yarn fell in the zone B. It indicated

that the cost performance of cashmere siro-spun yarn is less than that of the rabbit hair ring-spun yarn.

Therefore the rabbit hair ring-spun yarn is more worthy to buy for the consumers. For the

manufacturers, it is necessary to modify their technologies and reduce the cost price of the cashmere

siro-spun yarn to improve its cost performance.

References

[1] Suozhang Cai, Hongbin Zhang, Youwen Li, in The principle and method of mathematical

modeling , published by China ocean press(2000) in chinese

[2] Chongwen Yu, in Spinning process design and quality control, published by China textile

press(2005) in chinese

[3] Mu Yao, in Textile material science, by China textile press(2009) in chinese

Advanced Materials Research Vol. 331 43

Advances in Textile Engineering 10.4028/www.scientific.net/AMR.331 Comparison of the Cost Performance between Pure Cashmere Siro-Spun Yarn and Pure Rabbit Hair

Ring-Spun Yarn 10.4028/www.scientific.net/AMR.331.40