Thursday, September 3, 2009

ZIPPER AND SLIDER TESTING

I received many calls to write note on Zipper Testing, respecting their will below are some useful information on Zipper testing.

There are various methods to evaluate Zipper & Slider quality. The procedures in various quality
standards worldwide are more or less similar and are documented well under ASTM, ISO, BIS, JIS,
DIN, ISI and other well known International Standards.
Zipper & Slider strengths are checked as a routine inspection, For this the method laid out in
JIS-S3015 is used. The same standard is used by the YKK also, the world's leading Zipper manufacturer.
The basic strength can be determined based on the following inspection methods, from which all round
strength appropriate for respective uses can be judged.

TENSILE TESTING OF CROSSWISE ZIPPER STRENGTH
To determine the Zipper Strength the Zipper Chain in closed position is clamped
in-between specially designed Jaws of 25 mm width and pulled at a fixed speed
at 90 degree angle to the chain interlocked direction.
The resistance is measured in Kgf till failur

TENSILE STRENGTH OF THE SLIDER

Slider tensile strength test

The Body to Puller Strength is measured by this test. The complete slider is mounted on a special jig and load is applied to the Puller while keeping the Body fixed at 90 degrees. The resistance of the slider is measured till failure and is recorded in Kgf.
Tensile Tester velocity used in the above tests varies between 100~300 mm / min and the standard Clamp width used is 25mm.

TOP STOP HOLDING STRENGTH

Top stop holding strength test

The lower part of an interlocked Zipper is clamped and the Slider is pulled
right up to the top stop. Holding strength is measured by pulling the Slider
against the Top Stop in the Tensile Testing machine.

BOTTOM STOP HOLDING STRENGTH


Bottom stop holding strength test
A slider is pulled down till the end so that it touches the bottom stop and then the top single chains are opened to the right and left sides and are clamped in the Tensile tester. Bottom stop holding strength and resistance of the Zipper teeth inside the Slider are measured.

BOX HOLDING STRENGTH


Box holding strength test

The open part is fixed to the tensile tester clamps.
The clamps cover only on the area where the reinforcement tape exists as shown in the figure and the tensile strength is measured till failure.

SLIDER LOCK STRENGTH


A slider is locked around the middle of a zipper chain and top single chains are opened to the right and left sides. Locking strength of the Slider to the Zipper and resistance of the teeth inside the slider are measured.

Crosswise Tensile Strength Test Results for CFC Zippers

Test Procedure as per JIS-S3015, DIN-3416, DIN-3418, DIN-3419 , A.S 2332, B.S 3084
ITEM BEFORE TEST AFTER TEST BREAKING STRENGTH KGF

Details will be given on next page it is under construction

Sunday, July 26, 2009

Tensile Strength Testing of Fiber ASTM C1359-05

Test Method for Monotonic Tensile Strength Testing of Continuous Fiber-Reinforced Advanced Ceramics With Solid Rectangular Cross-Section Test Specimens at Elevated Temperatures

This test method covers the determination of tensile strength including stress-strain behavior under monotonic uniaxial loading of continuous fiber-reinforced advanced ceramics at elevated temperatures. This test method addresses, but is not restricted to, various suggested test specimen geometries as listed in the appendix. In addition, test specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates (force rate, stress rate, displacement rate, or strain rate), allowable bending, temperature control, temperature gradients, and data collection and reporting procedures are addressed. Tensile strength as used in this test method refers to the tensile strength obtained under monotonic uniaxial loading where monotonic refers to a continuous nonstop test rate with no reversals from test initiation to final fracture.

This test method applies primarily to advanced ceramic matrix composites with continuous fiber reinforcement: uni-directional (1-D), bi-directional (2-D), and tri-directional (3-D) or other multi-directional reinforcements. In addition, this test method may also be used with glass (amorphous) matrix composites with 1-D, 2-D, 3-D and other multi-directional continuous fiber reinforcements. This test method does not directly address discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics, although the test methods detailed here may be equally applicable to these composites.

Breaking Strength and Elongation of Cotton Fibers ASTM D1445-05

This test method covers the determination of (1) the tensile strength or breaking tenacity of cotton fibers as a flat bundle using a nominal zero gage length, or ( 2) the tensile strength or breaking tenacity and the elongation at the breaking load of cotton fibers as a flat bundle with 1/8-in. (3.2-mm) clamp spacing. This test method is applicable to loose fibers of untreated cottons whether taken before processing or obtained from a textile product.
This test method is designed primarily for use with special fiber bundle clamps and special strength testing instruments but may be used with other tensile strength and elongation testing machines when equipped with appropriate adapters to accommodate the fiber clamps. Other methods for measuring the breaking tenacity of fiber bundles include Test Method D 1294, Test for Breaking Strength of Wool Fiber Bundles-1 in gage Length; and D 5867, Test Method for Measurement of Physical Properties of Cotton Fibers by High Volume Instruments.
The values stated in either acceptable metric units or in other units shall be regarded separately as standard. The values expressed in each system may not be exact equivalents; therefore, each system must be used independently of each other, without combining values in any way.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


More on: Tensile Strength Testing ASTM C1359-05

Breaking Strength of Yarn in Skein Form

This test method covers the determination of the breaking strength of yarn in skein form. The observed breaking strength is expressed in units of force, and equations are provided to convert breaking strength to skein breaking tenacity and to skein break factor. Note 1 For the determination of the breaking strength and elongation of yarn by the single strand method, refer to Test Method D 2256.

This test method is applicable to spun yarns, either single or plied, composed of any fiber or blend of fibers, but is not suitable for yarns which stretch more than 5 % when the tension is increased from 2.5 to 7.5 mN/tex or 0.03 to 0.08 gf/denier.
This test method provides three options based on the perimeter of the reel, the number of wraps in the skein, and the machine speed or time-to-break.

Option 1 Eighty, forty, or twenty turns on a 1.50-m or 1.5-yd reel, broken at 300 mm/min or 12 in./min.

Option 2 Fifty turns on a 1.00-m or 1-yd reel, broken at 300 mm/min or 12 in./min.

Option 3 Fifty turns on a 1-m reel, broken in 20 s. Note 2 Option 1 is in general use in the United States, Option 2 is used for woolen yarns, and Option 3 has been proposed in the International Standards Organization (ISO) for international use.

More on: Test Method for Breaking Strength and Elongation of Cotton Fibers (Flat Bundle Method) ASTM D1445-05

FIBRE STRENGTH:

The different measures available for reporting fiber strength are
1. breaking strength
2. tensile strength and
3. tenacity or intrinsic strength
Coarse cottons generally give higher values for fiber strength than finer ones. In order, to compare strength of two cottons differing in fineness, it is necessary to eliminate the effect of the difference in cross-sectional area by dividing the observed fiber strength by the fiber weight per unit length.

The value so obtained is known as "INTRINSIC STRENGTH or TENACITY". Tenacity is found to be better related to spinning than the breaking strength.
The strength characteristics can be determined either on individual fibers or on bundle of fibers.

SINGLE FIBRE STRENGTH: The tenacity of fiber is dependent upon the following factors
chain length of molecules in the fiber orientation of molecules size of the crystallites distribution of the crystallites gauge length used the rate of loading type of instrument used and atmospheric conditions
The mean single fiber strength determined is expressed in units of "grams/tex". As it is seen the unit for tenacity has the dimension of length only, and hence this property is also expressed as the "BREAKING LENGTH", which can be considered as the length of the specimen equivalent in weight to the breaking load. Since tex is the mass in grams of one kilometer of the specimen, the tenacity values expressed in grams/tex will correspond to the breaking length in kilometers. BUNDLE FIBRE STRENGTH: In practice, fibers are not used individually but in groups, such as in yarns or fabrics. Thus, bundles or groups of fibers come into play during the tensile break of yarns or fabrics. Further, the correlation between spinning performance and bundle strength is at least as high as that between spinning performance and intrinsic strength determined by testing individual fibers. The testing of bundles of fibers takes less time and involves less strain than testing individual fibers. In view of these considerations, determination of breaking strength of fiber bundles has assumed greater importance than single fiber strength tests

More on: Test Method for Breaking Strength of Yarn in Skein Form
ASTM D1578 - 93

FIBRE STRENGTH:

The different measures available for reporting fiber strength are
1. breaking strength
2. tensile strength and
3. tenacity or intrinsic strength
Coarse cottons generally give higher values for fiber strength than finer ones. In order, to compare strength of two cottons differing in fineness, it is necessary to eliminate the effect of the difference in cross-sectional area by dividing the observed fiber strength by the fiber weight per unit length.

The value so obtained is known as "INTRINSIC STRENGTH or TENACITY". Tenacity is found to be better related to spinning than the breaking strength.
The strength characteristics can be determined either on individual fibers or on bundle of fibers.


SINGLE FIBRE STRENGTH: The tenacity of fiber is dependent upon the following factors
chain length of molecules in the fiber orientation of molecules size of the crystallites distribution of the crystallites gauge length used the rate of loading type of instrument used and atmospheric conditions
The mean single fiber strength determined is expressed in units of "grams/tex". As it is seen the unit for tenacity has the dimension of length only, and hence this property is also expressed as the "BREAKING LENGTH", which can be considered as the length of the specimen equivalent in weight to the breaking load. Since tex is the mass in grams of one kilometer of the specimen, the tenacity values expressed in grams/tex will correspond to the breaking length in kilometers. BUNDLE FIBRE STRENGTH: In practice, fibers are not used individually but in groups, such as in yarns or fabrics. Thus, bundles or groups of fibers come into play during the tensile break of yarns or fabrics. Further, the correlation between spinning performance and bundle strength is at least as high as that between spinning performance and intrinsic strength determined by testing individual fibers. The testing of bundles of fibers takes less time and involves less strain than testing individual fibers. In view of these considerations, determination of breaking strength of fiber bundles has assumed greater importance than single fiber strength tests


More on: Test Method for Breaking Strength of Yarn in Skein Form
ASTM D1578 - 93

FIBROGRAPH MEASUREMENT: ASTM D1447-89(1994)e1 Standard Test Method

This test method covers the measurement of the length and length uniformity of cotton fibers by use of the Fibrograph. The test method is applicable to fibers taken from raw or partially processed cotton or some types of cotton waste, but not to fibers from blends of cotton with other fibers or to fibers recovered from cotton yarns or fabrics.
This test method covers procedures for all models of the Digital Fibrograph, hereafter referred to as Fibrograph.
Fibro graph measurements provide a relatively fast method for determining the length uniformity of the fibers in a sample of cotton in a reproducible manner.
Results of fibro graph length test do not necessarily agree with those obtained by other methods for measuring lengths of cotton fibers because of the effect of fiber crimp and other factors.
Fibro graph tests are more objective than commercial staple length classifications and also provide additional information on fiber length uniformity of cotton fibers. The cotton quality information provided by these results is used in research studies and quality surveys, in checking commercial staple length classifications, in assembling bales of cotton into uniform lots, and for other purposes.
Fibro graph measurements are based on the assumptions that a fiber is caught on the comb in proportion to its length as compared to total length of all fibers in the sample and that the point of catch for a fiber is at random along its length.


Equipments for fiber testing
FIBRE FINENESS: Fineness Maturity Tester Method ASTM D1447-89(1994)e1Fiber fineness is another important quality characteristic which plays a prominent part in determining the spinning value of cottons. If the same count of yarn is spun from two varieties of cotton, the yarn spun from the variety having finer fibers will have a larger number of fibers in its cross-section and hence it will be more even and strong than that spun from the sample with coarser fibers.
Fineness denotes the size of the cross-section dimensions of the fiber. AS the cross-sectional features of cotton fibers are irregular, direct determination of the area of crosection is difficult and laborious. The Index of fineness which is more commonly used is the linear density or weight per unit length of the fiber. The unit in which this quantity is expressed varies in different parts of the world. The common unit used by many countries for cotton is micrograms per inch and the various air-flow instruments developed for measuring fiber fineness are calibrated in this unit.
Following are some methods of determining fiber fineness.
1- gravimetric or dimensional measurements
2- air-flow method
3- vibrating string method
Some of the above methods are applicable to single fibers while the majority of them deal with a mass of fibers. As there is considerable variation in the linear density from fiber to fiber, even amongst fibers of the same seed, single fiber methods are time-consuming and laborious as a large number of fibers have to be tested to get a fairly reliable average value.
It should be pointed out here that most of the fineness determinations are likely to be affected by fiber maturity, which is another important characteristic of cotton fibers.

AIR-FLOW METHOD(MICRONAIRE INSTRUMENT): The resistance offered to the flow of air through a plug of fibers is dependent upon the specific surface area of the fibers. Fineness tester has been evolved on this principle for determining fineness of cotton. The specific surface area which determines the flow of air through a cotton plug is dependent not only upon the linear density of the fibers in the sample but also upon their maturity. Hence the micronaire readings have to be treated with caution particularly when testing samples varying widely in maturity.
In the micronaire instrument, a weighed quantity of 3.24 gms of well opened cotton sample is compressed into a cylindrical container of fixed dimensions. Compressed air is forced through the sample, at a definite pressure and the volume-rate of flow of air is measured by a rotometer type flow meter. The sample for Micronaire test should be well opened cleaned and thoroughly mixed( by hand fluffing and opening method). Out of the various air-flow instruments, the Micronaire is robust in construction, easy to operate and presents little difficulty as regards its maintenance.


Fineness, Maturity and Micronaire
The chart shows the relationship between micronaire, fiber fineness, maturity ratio, and theoretical fiber diameter.
Fiber cross-section is assumed to be circular, which makes the fiber diameter lines on the graph approximate. Curves for micronaire level are empirical and therefore contain experimental error.
Fiber fineness (fiber linear density) is expressed in micrograms/in. or in millitex (µg/m). The practical range of fineness for U.S. Upland cotton is about 125-225 millitex.
Micronaire is expressed in dimensionless micronaire units. The practical micronaire range for U.S. Upland cotton is 2.0 – 6.0.
Maturity ratio is a measure of the relative amount of cellulose in the fiber cross-section. Values are dimensionless numbers in the 0.7 – 1.2 range.

FIBRE MATURITY:

Fiber maturity is another important characteristic of cotton and is an index of the extent of development of the fibers. As is the case with other fiber properties, the maturity of cotton fibers varies not only between fibers of different samples but also between fibers of the same seed. The causes for the differences observed in maturity, is due to variations in the degree of the secondary thickening or deposition of cellulose in a fiber.
A cotton fiber consists of a cuticle, a primary layer and secondary layers of cellulose surrounding the lumen or central canal. In the case of mature fibers, the secondary thickening is very high, and in some cases, the lumen is not visible. In the case of immature fibers, due to some physiological causes, the secondary deposition of cellulose has not taken sufficiently and in extreme cases the secondary thickening is practically absent, leaving a wide lumen throughout the fiber. Hence to a cotton breeder, the presence of excessive immaturefibers in a sample would indicate some defect in the plant growth. To a technologist, the presence of excessive percentage of immature fibers in a sample is undesirable as this causes excessive waste losses in processing lowering of the yarn appearance grade due to formation of neaps, uneven dyeing, etc.
An immature fiber will show a lower weight per unit length than a mature fiber of the same cotton, as the former will have less deposition of cellulose inside the fiber. This analogy can be extended in some cases to fibers belonging to different samples of cotton also. Hence it is essential to measure the maturity of a cotton sample in addition to determining its fineness, to check whether the observed fineness is an inherent characteristic or is a result of the maturity.

DIFFERENT METHODS OF TESTING MATURITY:MATURITY RATIO:The fibers after being swollen with 18% caustic soda are examined under the microscope with suitable magnification. The fibers are classified into different maturity groups depending upon the relative dimensions of wall-thickness and lumen. However the procedures followed in different countries for sampling and classification differ in certain respects. The swollen fibers are classed into three groups as follows
1. Normal : rod like fibers with no convolution and no continuous lumen are classed as "normal"
2. Dead : convoluted fibers with wall thickness one-fifth or less of the maximum ribbon width are classed as "Dead"
3. Thin-walled: The intermediate ones are classed as "thin-walled"
A combined index known as maturity ratio is used to express the results.
Maturity ratio = ((Normal - Dead)/200) + 0.70 where, N - %ge of Normal fibersD - %ge of Dead fibers

MATURITY CO-EFFICIENT: Around 100 fibers from Baer sorter combs are spread across the glass slide (maturity slide) and the overlapping fibers are again separated with the help of a teasing needle. The free ends of the fibers are then held in the clamp on the second strip of the maturity slide which is adjustable to keep the fibers stretched to the desired extent. The fibers are then irrigated with 18% caustic soda solution and covered with a suitable slip. The slide is then placed on the microscope and examined. Fibers are classed into the following three categories
1. Mature : (Lumen width "L")/(wall thickness") is less than 1
2. Half mature : (Lumen width "L")/(wall thickness "W") is less than 2 and more than 1
3. Immature : (Lumen width "L")/(wall thickness "W") is more than 2


About four to eight slides are prepared from each sample and examined. The results are presented as percentage of mature, half-mature and immature fibers in a sample. The results are also expressed in terms of "Maturity Coefficient"
Maturity Coefficient = (M + 0.6H + 0.4 I)/100 Where,
M is percentage of Mature fibersH is percentage of Half mature fibersI is percentage of Immature fibers
If maturity coefficient is
less than 0.7, it is called as immature cotton
between 0.7 to 0.9, it is called as medium mature cotton
above 0.9, it is called as mature cotton
AIR FLOW METHOD FOR MEASURING MATURITY:
There are other techniques for measuring maturity using Micronaire instrument. As the fineness value determined by the Micronaire is dependent both on the intrinsic fineness (perimeter of the fiber) and the maturity, it may be assumed that if the intrinsic fineness is constant then the Micronaire value is a measure of the maturity
DYEING METHODS: Mature and immature fibers differ in their behavior towards various dyes. Certain dyes are preferentially taken up by the mature fibers while some dyes are preferentially absorbed by the immature fibers. Based on this observation, a differential dyeing technique was developed in the United States of America for estimating the maturity of cotton. In this technique, the sample is dyed in a bath containing a mixture of two dyes, namely Diphenyl Fast Red 5 BL and Chlorantine Fast Green BLL. The mature fibers take up the red dye preferentially, while the thin walled immature fibers take up the green dye. An estimate of the average of the sample can be visually assessed by the amount of red and green fibers.


More on: FIBRE STRENGTH:

FIBRE TESTING

Yarn Fiber Testers


IMPORTANCE OF RAW MATERIAL IN YARN MANUFACTURING:
Raw material represents about 50 to 70% of the production cost of a short-staple yarn. This fact is sufficient to indicate the significance of the raw material for the yarn producer. It is not possible to use a problem-free raw material always, because cotton is a natural fiber and there are many properties which will affect the performance. If all the properties have to be good for the cotton, the raw material would be too expensive. To produce a good yarn with these difficulties, an intimate knowledge of the raw material and its behavior in processing is a must.
Fiber characteristics must be classified according to a certain sequence of importance with respect to the end product and the spinning process. Moreover, such quantified characteristics must also be assessed with reference to the following

1. what is the ideal value?
2. what amount of variation is acceptable in the bale material?
3. what amount of variation is acceptable in the final blend

Such valuable experience, which allows one to determine the most suitable use for the raw material, can only be obtained by means of a long, intensified and direct association with the raw material, the spinning process and the end product.
Low cost yarn manufacture, fulfilling of all quality requirements and a controlled fiber feed with known fiber properties are necessary in order to compete on the world's textile markets. Yarn production begins with the raw material in bales, whereby success or failure is determined by the fiber quality, its price and availability. Successful yarn producers optimize profits by a process oriented selection and mixing of the raw material, followed by optimization of the machine settings, production rates, operating elements, etc. Simultaneously, quality is ensuredby means of a closed loop control system, which requires the application of supervisory system at spinning and spinning preparation, as well as a means of selecting the most suitable bale mix.

BASIC FIBRE CHARACTERISTICS: A textile fiber is a peculiar object. It has not truly fixed length, width, thickness, shape and cross-section. Growth of natural fibers or production factors of manmade fibers are responsible for this situation. An individual fiber, if examined carefully, will be seen to vary in cross-sectional area along it length. This may be the result of variations in growth rate, caused by dietary, metabolic, nutrient-supply, seasonal, weather, or other factors influencing the rate of cell development in natural fibers. Surface characteristics also play some part in increasing the variability of fiber shape. The scales of wool, the twisted arrangement of cotton, the nodes appearing at intervals along the cellulose natural fibers.

Following are the basic characteristics of cotton fiber

1. fiber length
2. fineness
3. strength
4. maturity
5. Rigidity
6. fiber friction
7. structural features

STANDARD ATMOSPHERE FOR TESTING: The atmosphere in which physical tests on textile materials are performed. It has a relative humidity of 65 + 2 per cent and a temperature of 20 + 2° C. In tropical and sub-tropical countries, an alternative standard atmosphere for testing with a relative humidity of 65 + 2 per cent and a temperature of 27 + 2° C may be used.

FIBRE LENGTH: The "length" of cotton fibers is a property of commercial value as the price is generally based on this character. To some extent it is true, as other factors being equal, longer cottons give better spinning performance than shorter ones. But the length of cotton is an indefinite quantity, as the fibers, even in a small random bunch of cotton, vary enormously in length. Following are the various measures of length in use in different countries
mean length
upper quartile
effective length
Modal length
2.5% span length
50% span length
Mean length: It is the estimated quantity which theoretically signifies the arithmetic mean of the length of all the fibers present in a small but representative sample of the cotton. This quantity can be an average according to either number or weight.
Upper quartile length: It is that value of length for which 75% of all the observed values are lower, and 25% higher.
Effective length: It is difficult to give a clear scientific definition. It may be defined as the upper quartile of a numerical length distribution eliminated by an arbitrary construction. The fibers eliminated are shorter than half the effective length.
Modal length: It is the most frequently occurring length of the fibers in the sample and it is related to mean and median for skew distributions, as exhibited by fiber length, in the following way(Mode-Mean) = 3(Median-Mean)
where, Median is the particular value of length above and below which exactly 50% of the fibers lie.
2.5% Span length: It is defined as the distance spanned by 2.5% of fibers in the specimen being tested when the fibers are parallelized and randomly distributed and where the initial starting point of the scanning in the test is considered 100%. This length is measured using "DIGITAL FIBROGRAPH"
50% Span length: It is defined as the distance spanned by 50% of fibers in the specimen being tested when the fibers are parallelized and randomly distributed and where the initial starting point of the scanning in the test is considered 100%. This length is measured using "DIGITAL FIBROGRAPH".
The South India Textile Research Association (SITRA) gives the following empirical relationships to estimate the Effective Length and Mean Length from the Span Lengths.
Effective length = 1.013 x 2.5% Span length + 4.39 Mean length = 1.242 x 50% Span length + 9.78

FIBRE LENGTH VARIATION: Even though, the long and short fibers both contribute towards the length irregularity of cotton, the short fibers are particularly responsible for increasing the waste losses, and cause unevenness and reduction in strength in the yarn spun. The relative proportions of short fibers are usually different in cottons having different mean lengths; they may even differ in two cottons having nearly the same mean fiber length, rendering cotton more irregular than the other. It is therefore important that in addition to the fiber length of cotton, the degree of irregularity of its length should also be known. Variability is denoted by any one of the following attributes
1. Co-efficient of variation of length (by weight or number)
2. irregularity percentage
3. Dispersion percentage and percentage of short fibers
4. Uniformity ratio
Uniformity ratio is defined as the ratio of 50% span length to 2.5% span length expressed as a percentage. Several instruments and methods are available for determination of length. Following are some
· Shirley comb sorter
· Baer sorter
· A.N. Stapling apparatus
· Fibro graph
uniformity ration = (50% span length / 2.5% span length) x 100uniformity index = (mean length / upper half mean length) x 100

SHORT FIBRES: The negative effect of the presence of a high proportion of short fibres is well known. A high percentage of short fibers are usually associated with, - Increased yarn irregularity and ends drown which reduce quality and increase processing costs - Increased number of naps and slubs witch is detrimental to the yarn appearance - Higher fly liberation and machine contamination in spinning, weaving and knitting operations. - Higher wastage in combing and other operations. While the detrimental effects of short fibers have been well established, there is still considerable debate on what constitutes a 'short fiber'. In the simplest way, short fibers are defined as those fibers which are less than 12 mm long. Initially, an estimate of the short fibers was made from the staple diagram obtained in the Baer Sorter method
Short fiber content = (UB/OB) x 100
While such a simple definition of short fibers is perhaps adequate for characterizing raw cotton samples, it is too simple a definition to use with regard to the spinning process. The setting of all spinning machines is based on either the staple length of fibers or its equivalent which does not take into account the effect of short fibers. In this regard, the concept of 'Floating Fiber Index' defined by Hertel (1962) can be considered to be a better parameter to consider the effect of short fibers on spinning performance. Floating fibers are defined as those fibers which are not clamped by either pair of rollers in a drafting zone.
Floating Fiber Index (FFI) was defined as
FFI = ((2.5% span length/mean length)-1)x(100)
The proportion of short fibers has an extremely great impact on yarn quality and production. The proportion of short fibers has increased substantially in recent years due to mechanical picking and hard ginning. In most of the cases the absolute short fiber proportion is specified today as the percentage of fibers shorter than 12mm. Fibro graph is the most widely used instrument in the textile industry

More on: FIBROGRAPH MEASUREMENT: ASTM D1447-89(1994)e1 Standard Test Method

FIBROGRAPH MEASUREMENT: ASTM D1447-89(1994)e1 Standard Test Method

This test method covers the measurement of the length and length uniformity of cotton fibers by use of the Fibrograph. The test method is applicable to fibers taken from raw or partially processed cotton or some types of cotton waste, but not to fibers from blends of cotton with other fibers or to fibers recovered from cotton yarns or fabrics.
This test method covers procedures for all models of the Digital Fibrograph, hereafter referred to as Fibrograph.
Fibro graph measurements provide a relatively fast method for determining the length uniformity of the fibers in a sample of cotton in a reproducible manner.
Results of fibro graph length test do not necessarily agree with those obtained by other methods for measuring lengths of cotton fibers because of the effect of fiber crimp and other factors.
Fibro graph tests are more objective than commercial staple length classifications and also provide additional information on fiber length uniformity of cotton fibers. The cotton quality information provided by these results is used in research studies and quality surveys, in checking commercial staple length classifications, in assembling bales of cotton into uniform lots, and for other purposes. Fibro graph measurements are based on the assumptions that a fiber is caught on the comb in proportion to its length as compared to total length of all fibers in the sample and that the point of catch for a fiber is at random along its length.

More On: FIBRE FINENESS

BASIC FIBRE CHARACTERISTICS

STANDARD ATMOSPHERE FOR TESTING:

A textile fiber is a peculiar object. It has not truly fixed length, width, thickness, shape and cross-section. Growth of natural fibers or production factors of manmade fibers are responsible for this situation. An individual fiber, if examined carefully, will be seen to vary in cross-sectional area along it length. This may be the result of variations in growth rate, caused by dietary, metabolic, nutrient-supply, seasonal, weather, or other factors influencing the rate of cell development in natural fibers. Surface characteristics also play some part in increasing the variability of fiber shape. The scales of wool, the twisted arrangement of cotton, the nodes appearing at intervals along the cellulose natural fibers.

Following are the basic characteristics of cotton fiber

1. fiber length
2. fineness
3. strength
4. maturity
5. Rigidity
6. fiber friction
7. structural features

STANDARD ATMOSPHERE FOR TESTING: The atmosphere in which physical tests on textile materials are performed. It has a relative humidity of 65 + 2 per cent and a temperature of 20 + 2° C. In tropical and sub-tropical countries, an alternative standard atmosphere for testing with a relative humidity of 65 + 2 per cent and a temperature of 27 + 2° C may be used.

FIBRE LENGTH: The "length" of cotton fibers is a property of commercial value as the price is generally based on this character. To some extent it is true, as other factors being equal, longer cottons give better spinning performance than shorter ones. But the length of cotton is an indefinite quantity, as the fibers, even in a small random bunch of cotton, vary enormously in length. Following are the various measures of length in use in different countries
mean length, upper quartile , effective length, Modal length,2.5% span length,
50% span length


Mean length: It is the estimated quantity which theoretically signifies the arithmetic mean of the length of all the fibers present in a small but representative sample of the cotton. This quantity can be an average according to either number or weight.
Upper quartile length: It is that value of length for which 75% of all the observed values are lower, and 25% higher.
Effective length: It is difficult to give a clear scientific definition. It may be defined as the upper quartile of a numerical length distribution eliminated by an arbitrary construction. The fibers eliminated are shorter than half the effective length.
Modal length: It is the most frequently occurring length of the fibers in the sample and it is related to mean and median for skew distributions, as exhibited by fiber length, in the following way(Mode-Mean) = 3(Median-Mean)
where, Median is the particular value of length above and below which exactly 50% of the fibers lie.
2.5% Span length: It is defined as the distance spanned by 2.5% of fibers in the specimen being tested when the fibers are parallelized and randomly distributed and where the initial starting point of the scanning in the test is considered 100%. This length is measured using "DIGITAL FIBROGRAPH"
50% Span length: It is defined as the distance spanned by 50% of fibers in the specimen being tested when the fibers are parallelized and randomly distributed and where the initial starting point of the scanning in the test is considered 100%. This length is measured using "DIGITAL FIBROGRAPH".
More on: FIBRE LENGTH VARIATION

FIBRE TESTING

IMPORTANCE OF RAW MATERIAL IN YARN MANUFACTURING:
Raw material represents about 50 to 70% of the production cost of a short-staple yarn. This fact is sufficient to indicate the significance of the raw material for the yarn producer. It is not possible to use a problem-free raw material always, because cotton is a natural fiber and there are many properties which will affect the performance. If all the properties have to be good for the cotton, the raw material would be too expensive. To produce a good yarn with these difficulties, an intimate knowledge of the raw material and its behavior in processing is a must.
Fiber characteristics must be classified according to a certain sequence of importance with respect to the end product and the spinning process. Moreover, such quantified characteristics must also be assessed with reference to the following

1. what is the ideal value?
2. what amount of variation is acceptable in the bale material?
3. what amount of variation is acceptable in the final blend

Such valuable experience, which allows one to determine the most suitable use for the raw material, can only be obtained by means of a long, intensified and direct association with the raw material, the spinning process and the end product.
Low cost yarn manufacture, fulfilling of all quality requirements and a controlled fiber feed with known fiber properties are necessary in order to compete on the world's textile markets. Yarn production begins with the raw material in bales, whereby success or failure is determined by the fiber quality, its price and availability. Successful yarn producers optimize profits by a process oriented selection and mixing of the raw material, followed by optimization of the machine settings, production rates, operating elements, etc. Simultaneously, quality is ensuredby means of a closed loop control system, which requires the application of supervisory system at spinning and spinning preparation, as well as a means of selecting the most suitable bale mix.

More on BASIC FIBRE CHARACTERISTICS

Saturday, July 18, 2009

M & S Pilling test method – II, I.C.I. pill box

Pilling test method – II (Marks & Spencer)
PURPOSE: To evaluate the potential of fabric to pill.
APPARATUS:
1. I.C.I. pill box (speed 60 rpm +/- 2 rpm) with standard cork as specified in BS5811: 1986.
2. Molded Polyurethane pilling tubes.
3. Specimen mounting jig (see Equipment List Ref 13O and note 2).
4. Photographic standards, woven or knitted as applicable.
5. Marks & Spencer template for specimen preparation.
6. Lock or chain stitch sewing machine.
7. White PVC tape 19mm wide.
8. Pilliscope.
9. Soft brush.
10. Standard maintenance fabric.

Test Specimen:
Fabrics for washable garments should be washed as described in Method of Test P16 “ Washing Prior to Pilling Methods I and II”. If applicable record any changes that may occur during washing, e g. fuzzing, matting, surface disturbance.
Using the template mark and cut four squares 125 mm x 125 mm. A sample approximately 190 mm x 60 mm should be kept fpr use during assessment. Avoid fabric within 50 mm of the selvedge.
Mark the length direction of the fabric on the back of each square to ensure accurate preparation and mounting of the specimens.
Where a fabric has no discernable face, test both side.
METHOD:
1. Prepare two length and two width specimens by folding in half, ensuring the face is on the inside.
2. Sew a seam parallel to tie fold (12 mm from the dut edge) to form a tube with an open seam.
3. Cut 10 mm from one end to make the samples 115mm long.
4. Turn the four specimens face outwards.
5. Mount the four specimens on to the polyurethane tubes. To avoid unnecessary handling of the specimens always:
a) Collapse the tube onto the two pronged jig.
b) Push the metal sleeve over the tube.
c) Slide a specimen with the seam opened out and fixed onto the sleeve.
d) Hold the specimen gently and remove the sleeve leaving the specimen firmly mounted (not loose or tight) on the tube with an equal amount of polyurethane protruding at each end.
e) Remove the tube from the jig.
6. To secure the specimen to the tube apply to each end a PVC tape of sufficient length to wrap around one and a half times so that 6 mm of polyurethane tube is visible at each end.
7. Clean out the pill box with a soft brush.
8. Place the set of four tubes on one pilling box.
9. Run the box for the required revolutions as specified un the appropriate performance standard.
10. After testing, remove the specimens. Examine the inside of the box and record the presence of any loose pills and fabric debris.
11. Carefully remove the PVC tape.
12. Cut along the seam to remove the specimen from the tubes.
13. Trim the untested areas covered by the tape.
ASSESSMENT:
1. Grading should be carried out in the dark room or curtained of area.
2. Select the appropriate woven or knitted photographic standards for use in the pilliscope.
3. Grade each specimen in turn by placing in the pilliscope and compare the degree of pilling against the standard photographs. Record the grade.
4. Mount the graded specimens by stapling on to size A4 card. Mount the strip of untested fabric across the card between the two pairs of specimens.

Marks & Spencer Pilling test method -1

Pilling test method – I (Marks & Spencer)
PURPOSE: To assure the assistance of woven shirting and sheeting fabrics to pilling.
APPARATUS: 1.Martindale Abrasion machine
2.Felt (See note 1 and 2 and equipment ../default Ref 13D)
3.Polyester foam (See note 2 and equipment ../default 13E)
4.Pilliscope
5.Photographic standards.

Test Specimens:
Avoid fabric within 50 mm of the selvedge. Take a specimen of sufficient size to cut four150mm squares and four circles 38mm diameter. Wash as described in Method of Test P16 “Washing prior to Pilling Methods I & II)

Method:
1.Place one test specimen circle face down in the base of each sample holder. Cover each specimen with a circle of polyester foam 38mm in diameter (see note 2). Place on top of the foam the interior metal specimen support and assemble the top and base of the specimen.
2. Place a 150 mm circle/square of felt on each of the base plates ( see note 1).
3. Place one 150 mm square of the washed fabric over each of the squares of felt. Ensure the fabric has an even tension by using the tensioning weight ( provided with the machine). Secure the fabric in position with the retaining frame and remove the tensioning weight.
4. Secure four specimen holders on the top plate using the metal spindles so that the fabric face of each of the specimen is in contact with the fabric on its respective base plate. DO NOT USE ADDITIONAL WEIGHTS.
5. Run the machine for
a. Men's and boys shirting's 100 Revolutions
b. Sheeting 400 Revolutions

Results:
Mount the four test samples on card against unwashed fabric and view on the Pilliscope comparing against Marks & Spencer Photographs standard copy.
Report the average of the four results to the nearest ½ grade.
Notes:
1. Felt used in the test should be of mass per unit area 576+/- 50 grams/metre2 and 3 +/- 0.5m.m thick. The felt should be renewed after every 100 hours of test or if it’s found to be too much soiled. The felt should be retensioned for every 5000 revolutions during the running period.
2. Use white polyester foam complying with the following specification as determined by BS4443 for flexible Cellular foams:-
density 29.31 kg/m2
indentation hardness 170-120N
thickness 3+/- 1 mm
The foam should be stored in the dark. A new foam piece should be used for each test.

Light Fastness Test

Test for Light Fastness:
Nowadays the criterion of light fastness is a major concern amongst the dyers.
The stringent requirement of light fastness is getting more and more importance in the European as well as in the American market. It is very much essential to understand the different test methods, grading and factors affecting light fastness.
Generally it is difficult to achieve good grade of light fastness in light, medium, tricky shades viz., khaki, olive, grey, browns etc. A proper combination always helps to arrive at the customer requirement.




Generally two methods of testing are widely accepted by most of the customers. They are:
American Test Method (AATCC 16E) or Option 3
British Test Method (ISO 105/BO2)


Some more points that affect the fastness of a printed fabric:
The fastness to light of a print is not governed solely by the colorant. It is also very dependent on the colorant concentration, the thickness of the layer and the binder; other factors such as the spectral composition of the incident light and the atmospheric humidity also play a role. Consequently, it is very difficult to exactly quantify fastness to light. The values are merely given as a guide to formulators in carrying out their own tests.
AMERICAN TEST METHOD (AATCC 16E) or Option 3
This is an accelerated test method for testing of light fastness. There are different options in this method which are A, B, C, D, E, F, G, H, I, J. These options differ from each other on the basis of light source, panel temperature and humidity. Generally AATCC 16E method is widely used for testing purpose. In this method a test specimen is exposed under the condition specified in various test methods for 20hours, 40 hours or 60 hours and the factors affecting light fastness.
Generally for garment sector the assessment of light fastness is done after 20AFU where as in the case of furnishing fabrics, car upholstery the grading is assessed after 40-60 AFU.


Grading:
Grading of light fastness in this method is given on the basis of grey scale with rating of 1-5. One being poor and the five being the best.
Rating 3 is normally acceptable for most of the requirements.


BRITISH TEST METHOD (ISO 105/BO2)
The light fastness of dyed fabric is evaluated by exposing the fabric samples to xenon ARC. Even though the light sources are same, other conditions are different.


Grading:
The fastness to light is tested in accordance with DIN 16525. The degree of fading is assessed by comparison with the blue scale for wool (DIN EN ISO 105-B01). The fastnesses to light ratings are as follows:


Rating Property 1 very poor 2 poor 3 moderate 4 fairly good 5 good 6 very good 7 excellent 8 outstanding
There is no direct relation between the ratings of both the above methods. AATCC 16E (option 3) method (20AFU) is a quick method, while ISO 105/BO2 method takes much longer time where light fastness ratings are high.

What is lightfastness?

What is lightfastness?
Lightfastness is the degree to which a dye resists fading due to light exposure. Different dyes have different degrees of resistance to fading by light. All dyes have some susceptibility to light damage, simply because their strong colors are indications that they absorb the wavelengths that they don't reflect back. Light is energy, and the energy that is absorbed by pigmented compounds may serve to degrade them or nearby molecules. certain Basic type dyes can cause damage when exposed to light.


Unfortunately, ultraviolet is not the only kind of light that causes damage. Visible light is quite sufficient to fade colored materials. In tests using a UV protectant, DyersLIST members Jerry Trapp and Sally Holmes found that the beautiful but poorly lightfast blue-violet, Procion type blue MX-7RX, actually showed an increased amount of damage. This was presumably caused by an interaction between the protectant and the dye; UV protectants in glass windows will surely do no harm, whether or not they are helpful. Most likely, UV protection will help protect some dyes, but not others.

Woven and knit fabrics Shrinkage Tests




WOVEN FABRIC SHRINKAGE AATCC-135 Method (ISO 3759)
Whirlpool Top Loading model number:3XGSC9455 Washing Machine is recommended by AATCC for AATCC test methods requiring repeated home laundering






1. Sample size 50 cms X 50 cms
2. Marking area 35 cms X 35 cms
3. Samples weight should be 1.8kg +/- 0.1 kg
(If the sample weight is less than 1.8kg put the dummy cloth and maintain the weight of 1.8 kgs).
4.Liquour Ratio : 1:50
5.Suitable detergent (0.5%) on the weight of sample i.e 1.8kgs
6.At 400C for 60 minutes in Wash-cator.
7.Dry the sample at 600C to 650C using tumble dryer.
8.Press the sample in flat bed hot press at 1500 +/- 15°C with 30 gms/cm2 pressure.
9.Cool the sample and measure.
Shrinkage for Cotton Hosiery IS-3326
1.Liquor Ratio 1:50
2.Temperature : 30 to 35°C
3.Suitable Wetting agents (detergent) 0.5% on the weight of the hosiery sample.
4.Sample size 20 x 20 cms.
5.Marking area 14 x 15 cms (mark with marking scale).
6. Time 2 hours at 30 to 35°C
7.After that dry at room temperature.
8.Measure.
9.Shrinkage % = [100 x (a-b)]/a
where a = Distance between two ends after treatment.

Tensile Tests



Tensile (breaking) strength
Fabric samples are clamped in the jaws of a tensile tester and pulled apart until they break. Three samples are tested across the warp and three across the weft and the average breaking strength established is expressed in Newtons. BS 2543 states that tensile strength should be as follows for the different grades of intended duty

Breaking Strength and Elongation of
Textile Fabrics (Grab Test) ASTM D5034


The grab and modified grab tests determine breaking
strength and elongation of wet or dry textile fabrics. A grab
test is a tensile test where the center of the specimen width
is gripped in the clamps. The modified grab test is similar -
lateral slits are made mid-length of the specimen severing
all yarns bordering that portion of the specimen held
between the two clamps.
The grab test applies to woven, non-woven, and felted
fabrics, while the modified grab test is used for woven
fabrics. The method is not used for glass fabrics, knitted
fabrics or high stretch fabrics.
The grab test determines the effective strength of the
fabric: the strength of the yarns in a specified width with
fabric assistance from the adjacent yarns. It doesn’t reflect
yarn strength actually gripped between clamps. The
modified grab test determines the breaking force of fabrics
with constructions in which the application of tensile stress
on ravel strip specimens produces further unraveling. It
applies to high-strength fabrics.
Grab test: front grip face measures 1 inch by 1 or 2 inches,
the longer dimension along the vertical.
Modified grab test: front grip face measures 1 inch by 2
inches, with the longer dimension along the vertical.

Overall Test System Requirements
• Size System to generate highest expected load
• Select load cells for sample breaks at 10 to 90% of
load cell range
• Define Jaws - Grab Test or Modified Grab Test
with either rubber coated or smooth surfaces

Friday, July 17, 2009

Crocking or Rubbing fastness

Crocking or Rubbing fastness
Reactive dyes being water soluble it is difficult to achieve the same level of wet rubbing ratings as compared to insoluble dyestuff and also dry rubbing. With water soluble dyes, apart from the bleeding of the dyestuff from the rubbed area, finely distributed substrate particles also rub off on the surface of crockmeter cloth.
The problem is increasing with higher depths and fabrics like towels, corduroy etc. with rough surface. While evaluating the rating it is necessary to 9gnore such rub-off particles appearing on the crockmeter cloth and consider only the staining of the dye on the rubbed cloth.
Instrument used for checking is the standard crockmeter. However, test is quite sensitive and for getting consistent result, it is necessary to use standard crockmeter cloth, maintain uniform pressure for applying rubbing strokes and number of strokes. Besides, for wet rubbing, % moisture on the crock-cloth has to be kept to uniform level. For ISO-105 x 12 test method, rubbing cloth that has been wetted with water, has to be squeezed to contain its own weight of water. For AATCC 116-1995 methods, wet pick up is to be maintained between 65 ± 5% by squeezing the wet crockmeter cloth using a AATCC blotting paper. Any variation in the moisture content can lead to deviation in the rating. With high amount of moisture i.e.., wet pick up, ratings will be lower. Degree of staining is visually assessed using Grey scale for change of colour with grade of 1-5 where rating of 5 signify negligible change and 1 maximum change.
In order to get maximum achievable wet rubbing rating, with reactive dyes, it is absolutely necessary to remove all unfixed hydrolyzed dyes by proper soaping/washing of the sample before evaluating the ratings. Extraction with pyridine can be done to check the removal of hydrolyzed dyestuff.

Effect of depth of shade/selection of Dyes:
For reactive dyes with high solubility and good washing fastness properties, rating will be relatively higher. However, in deep shades, even with dyes with good washing fastness, a fastness rating of 2-3 on the grey scale is achievable and is considered satisfactory and acceptable. The liquid introduced with the wet crocking cloth results in all cases in a deterioration in rub fastness of up to 2 points in comparison to dry rubbing.

Effect of Mercerising
The colour transfer is relatively less, for the mercerised cotton and the rubbing fastness grade is higher. Due to change in the fiber structure on mercerising, there is a 30% less extent of removal of fiber particles, during wet rubbing and lesser amount of colour on the fibre for the same visual depth of shade.

Effect of finishing treatments
Different types of finishing treatment viz. softness, polysiloxanes, Zr-compounds, fluorocarbon, chitosan and cellulase enzymes etc. applied to dyes, fabrics do not show improvements in wet rubbing ratings. With some of the cross linking agents, rubbing fastness grade is lowered by 1/2 to 1 unit. In one of the recent study it is claimed that for reactive dyed blacks and bordeaux materials, with polyacrylate finishes there is some improvement in the wet rubbing fastness rating.

Gray Scales

Grey Scales
Before talking about any textile test or test method it is very necessary to have the knowledge about Gray scales.
Two types of gray scales are used below are the types and usage of them:

Grey Scale for Assessing Change in Shade
EN ISO 105-A03 / IUF 132 / VESLIC C 1211
This Grey Scale is for assessing the degree of change in shade caused to a dyed Textile fabric / yarn in color fastness tests. For example, the change of shade of wool and cotton fabrics in the washing fastness, perspiration fastness, etc.
The scale consists of nine pairs of gray color chips each representing a visual difference and contrast.
The fastness rating goes step-wise from:
Note 5 = no visual change (best rating) to Note 1 = a large visual change (worst rating).
The gray scale has the 9 possible values:
5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, 1.







It is now quite common to measure the Grey Scale change in color instrumentally. This is made using a suitable reflectance spectrophotometer according to the test method procedure,
EN ISO 105-A05.

Grey Scale for Assessing Staining
EN ISO 105-A03 / IUF 132 / VESLIC C 1211
This Grey Scale is for assessing the degree of staining caused by a dyed Textile / yarn in color fastness tests.
For example, the staining of wool and cotton fabrics in the wash fastness, perspiration fastness, etc.
The scale consists of nine pairs of gray color chips each representing a visual difference and contrast.
The fastness rating goes step-wise from:
Note 5 = no visual change (best rating) to Note 1 = a large visual change (worst rating).
The grey scale has the 9 possible values:
5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, 1.