abrasion characteristics of ring spun

7/23/2019 Abrasion Characteristics of Ring Spun

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The Abrasion Characteristics of Ring Spunand Open-End Yarns

Eric D. Bryan,Chongwen Yu

&

William Oxenham

Department of Textile and ApparelTechnology and Management

College of TextilesNorth Carolina State University

12thEFS Systems ForumNovember 4-5, 1999, Raleigh, N.C.


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Abstract

There is a general opinion that open end spun cotton yarns are more

abrasive than their ring spun counterparts. The major evidence for the

differences between the two yarn types is the supposed greater attrition suffered

by machinery parts (such as knitting needles) when processing rotor yarns. While

these opinions are founded on the claims from the industry, there is little

published data to support these views.

The paper describes an investigation into the role of spinning technique on

the abrasiveness of yarns. Open-end yarns produced at different production

speeds were compared with the equivalent ring spun yarns using a Lawson-

Hemphill CTT tester. The abrasiveness was assessed by running the yarn over a

wire and determining the length of yarn needed to break the wire.

The role of fiber type, machine type, production speed, and twist level are

assessed and the results from the tests are collated with data obtained from tests

on "commercial" yarns, which were obtained from the industry.


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Introduction:

The Constant Tension Transport (CTT), developed by Lawson-Hemphill,

is a versatile machine that allows a variety of yarn tests to be run just by utilizing

different attachments. With these additions, the CTT is able to run the following

tests:

Yarn-to-yarn friction;

Yarn-to-metal friction;

Yarn on metal abrasion;

Lint generation; and

Breaking strength.

The above list only names a few of the CTTs capabilities. The machine is

also unique because of its ability to keep the input tension constant throughout a

particular test. The input tension can be set to the desired tension, in grams, and

a lever arm adjusts/corrects for any changes in tension as the yarn is removed

from the package. The test speed and the percent elongation imposed on the

yarn are also adjustable.

For this research, the attachment for testing yarn on metal abrasion was

used. This attachment allows the yarn to pass over a copper wire and the

machine measures the meters of yarn needed to break the wire. A weight is

used to keep a preset tension on the copper wire. Figure 1 is a photograph of

the CTT with the yarn abrasion attachment connected. Figure 2 is a close up of

the abrasion attachment.


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Figure 1: CTT with abrasion attachment.

Figure 2: Abrasion attachment

The attachment to the right of the abrasion attachment is a tensiometer,

which can be used to measure the output tension of the yarn. Figure 3 is a

diagram of the abrasion attachment. The yarn comes in under Tension 1which

is held constant by the CTT, then passes over the first frictionless pulley. From


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that point, the yarn runs across the copper wire and then over the second pulley.

The yarn leaves the attachment under Tension 2, which is then measured by the

tensiometer.

Experimental Design:

In order to set up a standard with which to compare ring and rotor yarns,

a series of trials were run with different yarns. Possible variables for the testing

procedure were 1) yarn speed, 2) yarn tension, and 3) weight on the copper wire.

During the preliminary trials one variable was changed while the other two were

kept constant. This was done in order to achieve a standard which takes a

reasonable time but is not too lengthy. The conditions also had to be

acceptable for all yarns.

For the first set of tests, the yarn tension was changed, and the yarn

speed and weight on the copper wire were kept constant. Yarns were tested at

tensions from 40 grams to 70 grams in 10-gram increments. During the second

Rollers

CopperWire

Yarn

Tension 1 Tension2

Figure 3


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set of tests, the weight applied to the copper wire was changed and the speed

and input tension were kept constant. The weight on the wire was changed

between 100 and 300 grams. The final tests kept the input tension and the wire

weight constant and changed the yarn/test speed. The three test speeds used

were 180, 270, and 360 meters/minute.

From considerations of the time required for testing and the ability of all

yarns to be tested under these standard conditions, the following conditions

were adopted for all future comparison trials:

Test Speed 360 m/min Input Tension 60 grams

Weight on Wire 200 grams

Yarn Production:

All the yarns used for testing were produced in the Short Staple Spinning

Lab at the College of Textiles. Only new, 100% cotton was used to produce the

sliver for the rotor yarns, as well as the roving for the ring yarns. For the open-

end yarns, several different rotor speeds were used on both the Rieter and

Schlafhorst spinning frames. The Schlafhorst yarns were spun using five different

rotor speeds. The slowest was 80K and the speeds were increased by 10K up to

the fastest of 120K. The Rieter yarns had rotor speeds of 60K, 72K, 80K, 92K,

102.8K, 110K, and 122K. The same rotor size was used on both machines, and

ring spun yarns of the same count were produced for comparison. All yarns had

an approximate linear density of 20/1 Ne.


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Results of Typical Yarn Testing:

The ring and rotor yarns were all tested on the USTER 3, Tensojet, and

the Tensorapid. The yarns were then compared to each other according to

evenness and strength. From the following two graphs it can be seen that the

yarns from the Rieter and Schlafhorst machines are very close in both evenness

and strength.

Evenness (%CV) of Schlafhorst & RieterYarns

12.5

13

13.5

14

14.5

15

50 60 70 80 90 100 110 120 130

Rotor Speed (*1000)

Evenness(%C

V)

Rieter (dashed)

Schlafhorst

Comparison of Tenacity Values

77.5

88.5

99.510

10.511

11.512

12.513

13.514

60 70 80 90 100 110 120Rotor Speed (*1000)

Ten

acityMean(cN/tex)

Rieter Tensojet Schlafhorst TensojetRieter Tensorapid Schlaforst Tensorapid

Figure 4

Figure 5


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frames. The single point in the bottom left corner is an average of all the ring

Schlafhorst Yarn vs. Rieter Yarn

R2= 0.9473

R2= 0.089

4300

4500

4700

4900

5100

5300

5500

5700

60K

72K

80K

90K

92K

100K

102.8K

110K

120K

122K

Rotor Speed

AbrasionLength(meters)

Schlafhorst Yarn, 360 m/min, 60 grams

Rieter Yarn, 360 m/min, 60 gramsRing Spun, 360 m/min, 60 grams

spun yarns tested. It can be seen that rotor speed does have an effect on

abrasiveness. It is a little more noticeable with the Rieter yarns than with the

Schlafhorst yarns but they both show an increase in abrasiveness as the rotor

speed increases. It can also be seen that the Schlafhorst yarns were the least

abrasive, but both sets of rotor yarns (with the exception of the Rieter yarns

above 102K), were better than the comparable ring spun yarns.

The graph labeled as Figure 8 shows the relationship between belts and

rotor speed. There is a noticeable trend in the Rieter yarns that shows an

increase in the extent of belts as the rotor speed increases. This trend cannot be

generalized, however, since the same trend is not seen in the Schlafhorst yarns.

Figure 7


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Figure 8: Belts vs. Rotor Speed

2

3

4

5

6

7

8

50 60 70 80 90 100 110 120 130

Rotor Speed (*1000)

Belts(mm/c

m)

Schlafhorst

Rieter (triangle)

Figure 9 relates abrading length and belts. The abrading lengths of the

yarns from the two spinning systems are fairly close but the Rieter yarns again

seem to show a trend that is not evident in the Schlafhorst yarns. As the extent

of the belts increases, the Rieter yarns became more abrasive, i.e. the abrading

length decreased. The Schlafhorst yarns did not show a definite trend; therefore

this phenomenon cannot be generalized for all yarns.

Figure 9: ABRADING LENGTH vs. BELTS

4400

4600

4800

5000

5200

5400

5600

2 3 4 5 6 7 8

BELTS (mm/cm)

ABRADINGLENGTH

SCHLAFHORST (square)

RIETER


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Figure 10, shows the effect twist has on the abrasiveness of ring spun

yarns. Yarns were spun with various amounts of twist ranging from 15.5 tpi to 22

tpi.

Figure 10: Effect of Twist

4000

5000

6000

7000

8000

9000

14 16 18 20 22 24Twist (tpi)

AbrasionLength(m)

The graph shows that for the range of twists utilized, there appears to be a

general trend that as the twist increases the abrasion length increases. In other

words, the yarns become less abrasive as the twist per inch increases.

Conclusions:

It is apparent from the data presented that the two rotor spinning

machines produce yarns with different properties and while one may exhibit a

trend, this cannot be generally accepted as being true for all rotor yarns. The

different trends exhibited by the different spinning machines are not totally

unexpected but at this stage no satisfactory explanation can be proposed.

Perhaps the most challenging result to explain, particularly in the light of

supposed claims from the industry, is that for the cotton fiber used in the


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present trial there is no evidence of any significant difference in the

abrasiveness of rotor and ring spun yarns, and any difference which exists

tends to indicate that rotor yarns are superior (should give less abrasion of

machine components).

It has been claimed that a possible reason for differences between ring

and rotor yarns could be associated with silica content in the yarn. Samples of

each type of yarn were evaluated by ITC (Texas) and no evidence of silica was

found in any of the samples.

It is obvious that the results reported, seem to be contrary to expected

trends. While the role of twist seems strange (since it is assumed that higher

twist is associated with hard or harsh hand) the evidence is clearly showing the

opposite trend.

abrasion characteristics of ring spun

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