HAIRINESS IN YARN

I am very happy to add this article written by Mr.Kamatchi Sundaram , All india Service Manager of VOLTAS LTD. INDIA, in my site. He is one among the good technologists who has indepth knowledge about textile technology and spinning machines. I hope this information is of use to the technical people who browse through this site.

Hairiness is a measure of the amount of fibres protruding from the structure of the yarn. In the past, hairiness was not considered so important. But with the advent of high-speed looms and knitting machines, the hairiness has become a very important parameter.

In general, yarn spun with Indian cotton show high level of hairiness due to the following reasons.

1. High short fibre content in mixing.

2. Low uniformity ratio.

3. High spindle speeds.

Hence most of the Indian yarns have a hairiness index above 50% Uster standards. However, as this parameter is becoming more and more important, Indian spinners are concentrating more on this aspect and try to reach at least 25% standards by conducting lot of trials. He has conducted a lot of such studies on hairiness and he is pleased to share his learning’s with you.

Hairiness is measured in two different methods.

1. USTER HAIRINESS INDEX:

This is the common method followed in India. The hairiness index H corresponds to the total length of protruding fibres within the measurement field of 1cm length of the yarn.

2. ZWEIGLE HAIRINESS INDEX:

This zweigle hairiness measurement (S3) gives the number of protruding fibres more than 3 mm in length in a measurement length of one meter of the yarn.

From the above you can infer that Uster hairiness index give the total length of hairs whereas zweigle hairiness testers give the absolute number of fibres. Though the later measurement is more accurate, most of the Indian spinners are still following Uster hairiness index only.

The factors effecting hairiness can be sub divided into 3 major components.

a) The fibre properties.

b) Yarn parameters.

c) Process parameters.

a)THE FIBRE PROPERTIES:

Fibre length, Uniformity ratio, Micronaire and short fibre content are the properties exerting high influence on hairiness. Among the above the length and short fibre content exerting major influence. For a particular count, higher length of fibre leads to lesser hairiness and high short fibre content leads to high hairiness.

b)YARN PARAMETER:

Hairiness is dependent on the number of fibres present in the cross section of the yarn. Hence coarser yanrs have more hairiness compared to finer yarns.

The yarn twist is another major factor and higher twists lead to less hairiness up to a certain extent. This is the main reason while hosiery yarns normally have high hairiness compared to warp yarns.

However in a mill condition, the fibre parameters and yarn parameters cannot be adjusted. Hence the next topic, process parameters, assumes very high significance, as this is the only available option at the mill level to reduce the hairiness.

C) PROCESS PARAMETER:

The preparatory machines do not have a big influence on hairiness. The Speed frame, Ring frame and the Cone winder are the only machines to be attended for reduction in hairiness. I give below the various process parameters that can be attended for reducing the hairiness.

a)SPEED FRAME:

1. Roving hank: It plays a major role in the reduction of hairiness. For a particular count, the hairiness of the yarn goes down, as the roving hank is made finer and finer.

For example: If 30s yarn is spun with 0.8 and 1.0 hank, yarn made with 1.0 hank will give lesser hairiness than the yarn made with the 0.8 hank. Hence please conduct a trial with finer roving hank to reduce the hairiness.

The results of the study conducted recently at a leading mill are given below for your reference on this point.

TRIALS ON HAIRINESS

EFFECT OF ROVING HANK ON HAIRINESS

	Ring rail bottom po			Ring rail top postion
COUNT	24 ch	24 ch	24 ch	24 ch	24 ch	24 ch
ROVING HK	1.0	0.9	0.8	1.0	0.9	0.8
SPACER	3.0	3.0	3.0	3.0	3.0	3.0
U%	8.75	8.8	8.72	8.61	8.54	8.68
thin (-50%)	0	0	0	0	0	0
thick (+50%)	10	15	15	9	11	14
Neps (+200%)	12	18	21	12	14	18
Total IPI	22	33	36	21	25	32
Hairiness Index	7.52	7.86	8.45	6.4	6.48	7.09
Sh(-)	1.31	1.3	1.48	1.19	1.27	1.41

You would note from the above that the hairiness as well as imperfections have improved significantly by using finer hank of the roving.

2. Spacer Size: It is the normal tendency of the technicians to use spacer as thin as possible to reduce the U% and imperfections. But thinner spacers lead to higher hairiness. Hence please conduct a trial with a spacer, which is 1.0 to 1.5 mm thicker than existing spacer.

b)RING FRAME:

1. Ring Traveller: It is generally opined by many technicians that the traveller plays a major role in hairiness. Though selection of the traveller plays a small role in hairiness (specially with reference to the yarn clearance), it’s effect is quite less. This is because the yarn contact point with the traveller is quite far away from the ring and traveller contact point. Hence even if the traveller is run for a long time, the hairiness will not increase. But the breakage rate will increase.

2. Ring: It is the general opinion of some technicians that imported rings give lesser hairiness than Indian rings. It is also believed by technicians that older rings give more hairiness. Recent studies / trials conducted by us recently at a leading mill indicate this not to be true. Please refer the table below.

EFFECT OF RINGS ON HAIRINESS

RING COPS TRAIL (TOP POSITION OF THE RING RAIL)

PARAMETERS	old lmw rings	new lmw rings	bracker rings
NOMINAL COUNT	30s CH	30s CH	30s CH
U%	9.37	9.59	9.59
Thin (-50%)	0	0	0
Thick (+50%)	24	28	24
Neps (+200%)	51	52	58
Total IPI	75	80	82
Hairiness Index	5.4	5.26	5.33
Sh(-)	1.18	1.13	1.17

RING COPS TRAIL (BOTTOM POSITION OF THE RING RAIL)

PARAMETERS	old lmw rings	new lmw rings	bracker rings
NOMINAL COUNT	30s CH	30s CH	30s CH
U%	9.24	9.18	9.24
Thin (-50%)	0	0	0
Thick (+50%)	26	19	27
Neps (+200%)	49	44	46
Total IPI	75	63	73
Hairiness Index	6.11	6.06	6.22
Sh(-)	1.27	1.26	1.29

You would note from the above trials that:

a) There is no significant difference in hairiness between Imported & Indian rings.

b) There is also no significant difference in hairiness between a new and a one-year-old ring. However if the condition of the ring is highly worn out , it will affect the hairiness. In short the ring and traveller do not play a major role on hairiness compared to other process parameters, which are explained below.

3) SPACER SIZE: Size of the spacer plays significant role in reducing the hairiness. Many technicians have a tendency to use the thinnest spacer for reduction in U% and imperfections. However it leads to significant increase in hairiness.

A study conducted recently at a leading mill proves this point. Please refer the table below for the above study.

EFFECT SPACER SIZE ON HAIRINESS

	Ring rail bottom position		Ring rail Top position
COUNT	24s CH	24s CH	24s CH	24s CH
ROVING HK	0.8	0.8	0.8	0.8
SPACER	3.0	4.0	3.0	4.0
U%	8.7	9.06	8.58	8.76
thin (-50%)	0	0	0	0
thick (+50%)	8	15	7	12
Neps (+200%)	14	16	16	19
Total IPI	22	31	23	31
Hairiness Index	7.32	6.72	5.87	5.35
Sh(-)	1.27	1.19	1.07	1.06

You would note from the above that there is a significant reduction in hairiness by using thicker spacer. However the imperfection has also increased. .

The spacer should be selected such that optimum results are achieved with respect to imperfections as well as hairiness. We request you to conduct a trial with a spacer, which is 0.5 to 1mm thicker than the existing spacer. It is needless to mention that using thicker spacer will increase the imperfections. However if the reduction in hairiness is more significant than increase in imperfections it can be allowed.

4) TPI IN THE YARN: Increasing the TPI leads to reduction in hairiness and this is more significant in the case hosiery yarn. Hence if the hairiness is a bigger problem faced by mill, trials can be conducted by increasing the TPI up to the allowable limit for achieving reduction in hairiness.

5) LAPPET HEIGHT: Reduction in lappet height leads to direct reduction in hairiness. However care should be taken to ensure that the yarn does not touch the tip of the Empties. Please conduct trials with reduced lappet height (Formula: Lappet height = 2D+5mm).

6) SUCTION TUBE SETTING: The suction tube should be set such that the yarn does not touch the tip of the suction tube in running. If the yarn touches the suction tube due to improper setting, it will lead to increase in hairiness.

7) TRAVELLER SIZE: Usage of heavier traveller leads to reduction in hairiness.

For Example: If the breakage rate in 30s carded hosiery count is same with 4/O and 6/O traveller, using 4/O traveller will give lesser hairiness than 6/O traveller.

8) LIFT AND RING DIAMETER: Using lesser lift and lesser ring diameter will lead to direct and significant reduction in hairiness.

For Example: If 30s carded hosiery count is spun with 170/38 and 180/40 combination, spindle speeds remaining the same, the former combination will give much lesser hairiness than the later combination because of a reduction in the height and diameter of the yarn balloon while spinning.

C) CONE WINDER:

There will be a significant difference between the hairiness of the yarn at cop stage and at cone stage. The cone winding process increases the hairiness by 15 to 20%, which is unavoidable. However, if the modern AutoConers are not tuned properly, it will lead to increase in hairiness of much more than 20%. In this case the following points need attention.

1. WINDING SPEED: The speed of winding plays a significant role on increase in hairiness. The increase in winding speed leads to direct increase in the hairiness. The results of the study conducted recently at a leading mill are given below for your reference on this point.

EFFECT OF WINDING SPEED ON HAIRINESS

PARAMETERS	Cop result	winding speed 1200 m/min	winding speed 1400 m/min	winding speed 1600 m/min
NOMINAL COUNT	30 s CH	30 s CH	30 s CH	30 s CH
U%	9.37	9.59	9.6	9.53
Thin (-50%)	0	0	0	0
Thick (+50%)	16	14	15	17
Neps (+200%)	39	41	41	50
Total IPI	55	55	59	50
Hairiness Index	5.04	7.13	7.47	7.5
Sh(-)	1.08	1.59	1.66	1.73

You would note from the above that the hairiness increases more and more with the increase in the winding speed. However it is not economically feasible to run the AutoConer at slow speed just for achieving lesser hairiness. But all the AutoConers have a provision to adjust the speed of winding according to the stage of the cop and this is called variable speed arrangement. By selecting the right speeds at different stage of the cop the increase in hairiness can be controlled to a great extent.

2. YARN TENSION DURING WINDING: By optimizing the yarn tension the increase in hairiness can be controlled. The results of the study conducted recently at a leading mill are given below for your reference on this point.

PARAMETERS	tension 25 grams	tension 32 grams
NOMINAL COUNT	30/1 CH	30/1 CH
U%	9.73	9.68
Thin (-50%)	0	0
Thick (+50%)	23	19
Neps (+200%)	52	48
Total IPI	75	67
Hairiness Index	7.41	7.72
Sh(-)	1.74	1.79

You would note from the above that the hairiness can be reduced by optimizing the winding tension. This trial may be conducted at your mills for controlling the hairiness.

3. WAX PICK UP: It is the normal practice of many mills to apply wax on the hosiery yarn during winding. By controlling the wax pick up, the increase in hairiness can be reduced. The detail of the study recently conducted at a leading mill is given below for your reference.

EFFECT OF WAX PICK UP ON HAIRINESS

PARAMETERS	wax pick up 0.8 gms/kg	wax pick up 1.2 gms/kg
NOMINAL COUNT	30/1 s CH	30/1 s CH
U%	9.84	9.91
Thin (-50%)	0	1
Thick (+50%)	32	30
Neps (+200%)	89	112
Total IPI	121	1459
Hairiness Index	8.13	7.89
Sh(-)	1.84	1.87

We request you to conduct a study of this aspect at your mills for control of hairiness. Thus, there are several process parameters that can be optimized for controlling the hairiness. Unless the ring and traveller are in a worn out condition, the role played by the ring and traveller on hairiness is quite negligible on modern ring frames like LG5/1 and LR/6.