Evaluation of Textile Materials

Prof Apurba Das

Module No.#01
Lecture No. # 01
Evaluation of Textile Materials – Outline

Hello everyone, today we are going to start a new course which is called Evaluation of
Textile Material. So the Evaluation of Textile Material here will mainly deal with the
physical texting of textile material. Textile material in the form of fibre, yarn, fabric; also
we will discuss the intermediate material like sliver, roving. So in today’s discussion we
will discuss the introduction to the course, overall introduction ok.
(Refer Slide Time: 01:06)

Now basic outline of today's discussion is that first we will try to understand the need for
testing of textile material. Why do want to test textile material? Then we will discuss the
importance of standardization. Standard test method is extremely important and we will
discuss various standards available for testing textile material and also we will discuss
that what are the effects, we will get if we do not follow any standard method.

Next, so different standard for textile testing, after that we will discuss different terms related
to sample related to testing different standard definitions we will discuss. And at last we will
give the total overview of the entire course. So what are we going to discuss in this course
that we will give the overview before we start actual course.
(Refer Slide Time: 02:41)
So, first question is that why do we test textile material. What is the importance? So first is
that we have to check the quality of the material and suitability of the raw material for
particular application. For example suppose we want to produce a particular yarn and for that
we need a raw material like fibre say cotton; so for particular yarn, to achieve a particular
quality of yarn particular strength of yarn we need to know the strength of fibre, diameter of
fibre, length of fibre; so if we want to know, so how do we know? We have to check.

So, that is why we have to test the material. So, whether the raw material is suitable for a
particular application that we have to decide. So we have various raw materials available.
Different quality of raw materials available and particular quality is suitable to have
particular yarn. So, similarly for yarn, we have different types of yarn. So, we need to know
the characteristics of the yarn to have best quality fabric.

Next objective is that to monitor the production process. Like we are trying to manufacture a
particular end product say yarn; okay and the yarn our targeted strength, targeted uniformity
is there and to achieve that strength or uniformity we have to know the intermediate product
also. Like this is yarn so to produce this yarn we have to go through different intermediate
process.

So like, this is the raw fibre, say, raw cotton fibre. So from this fibre, we have to convert this
raw fibre to continuous strand this is called sliver. And from this sliver in next stage we have
to form a finer continuous strand which is known as roving. So to monitor this total entire
production process to achieve particular yarn we have to test the material in between us. If we
do not have better quality sliver or roving, we cannot get the required quality of yarn.

So, to monitor the production process we have to test at each and every stage. Next objective
is that the process development. Suppose a particular process let us say, for example blow
room. A blow room it has been observed that it is breaking the fibre. Large amount of fibre
breaking is taking place. So, what do you do? So, fibre breakage means reduction in length of
fibre.

So, what do you do, we have to test the fibre length before blow room process and if you
know the certain length before blow room and then after blow room process and we can see
the change percentage reduction in fibre length. In that way if it is beyond the acceptable
limit then what do we do we have to change the setting of the blow room or we have to
change the speed of the blow room.

So, not only in the blow room, for many other applications; like we want to impart certain
twist in a yarn and if we do not test the twist then we cannot actually set the material. So for
process development for any process development we need to test the machine. And then
assessment of the final product where the quality is acceptable or not; so whether the quality
is acceptable or not that assessment we have to know.

Suppose our yarn, after production of the yarn; yarn goes to the weaving department; the
weaving, it is a raw material for weaving. So and weaving needs the particular quality. Set
quality. That is the final product of the spinning but the raw material for weaving. So, that
quality checking we have to do. For that we need to test the material.
(Refer Slide Time: 08:27)
Another objective is that investigate the faulty machine. Suppose a particular machine is
generating a fault like thick and thin places in ring frame. So if we do not test the evenness of
the yarn; so we cannot identify the faulty location. So, if we test the material and that is called
root cause analysis. So, analysis of customer complaint, suppose a particular customer has
actually given send us a complaint that the yarn is highly non-uniform. It has got too much
thick and thin places. Or the yarn is poor in quality in terms of strength.

So, for that we have to first test the material. Thorough testing of the material is required to
identify the source of fault. If we cannot identify the source of fault then the total the machine
will keep on generating the fault; keep on producing the faulty material, so that the industry
cannot survive. So for that we need to test the material. Next is the product development and
research.

For any product development, for any research we have to test. So, we must understand the
testing. ok suppose we want to produce the new fabric, new material. So, you must test the
material. And last is that the Specification Testing. Our customer they give some
specification. Suppose spinning mill is trying to sell its product to a particular customer
abroad. So, what the customer gives, customer gives the specification; this is the uniformity
rate; U %; this is the strength; this is the hairiness all these parameter they give.

And you have to match these parameters. How do you match? For that we need to test. So all
these are the very important aspects of textile material and for that we have to test we have to
know the characteristics of the material.
(Refer Slide Time: 11:18)

So, after knowing the requirement of testing then we must know the need for standardization.
Why do we need to standardize the testing? Can we test material, any material at any
environment at any condition? That will result us the wide variation in results. For a
particular material it will give a wide range. So that the lack of reproducibility in the test
result may be due to, first is the variation in the material.

So, particularly textile material it is variable in nature; in terms of diameter, in terms of

So, if we can sample we will discuss in detail the sampling processes. The, may be random
sampling, may be any other types of sampling; that we will discuss in detail. So, proper
sampling if we can do then we can little bit minimize the variation of material. Use of
suitable statistical methods to analyze the test results like t tests, significance test. So we can
actually come to know whether the material is actually variable or not, that these things we
are able to understand this through the statistical methods.
(Refer Slide Time: 13:16)
Next is that variation due to test methods. So during testing, the result can change. For a same
material, if we do not test the material under standardized condition, you will land up with
totally different test results. This variation in test results is due to various factors. First is the
due to the operator. The person who is testing, suppose he is not taking care, proper care in
sample mounting, jaw he is not fixing, there is jaw slippage.

He is not following the test method, test procedure. Okay. He is not able to set the machine
apart a proper speed, proper guage length. So, all these results that due to operator’s
carelessness, we will land up with that different test results. Next is that proper size of the
specimen. See if we do not set the proper size, then we will have different test results for a
same material. We will land up with different test results.

Like one example is that, the guage length of yarn. So, this yarn if we test with a smaller
guage length we will get a particular strength value. But if we test with a longer guage length,
the test result will be totally different. All these results will discuss. But the thing is here the
specimen size actually affects the result widely. The material is same, same yarn but we will
land up with different result. We are using the same testing instrument, same speed; same
environment only by changing the size of the specimen our test results is changed.

Third is the atmospheric condition. In textile material most of the textile materials are
hygroscopic in nature. The characteristics of textile materials affects too much on
atmospheric condition, particularly the relative humidity. So the atmospheric condition has to
be perfect, the specified; it should be standardized. So, standard atmospheric condition must
be there otherwise it will land up with different results.

For cotton, if we increase the relative humidity, the strength of cotton will increase. But on
the other hand for viscose if we increase the relative humidity the strength of viscose will
decrease. So, to counteract this problem we have to set the specific relative humidity and
temperature. That is known as the standard atmospheric condition. Type of test equipments;
suppose if we test a fibre for strength in a single fibre test method or in bundle mode, bundle
fibre test, the test result will change.

So, type of test equipment, there are various types of equipments for a particular parameter.
For strength testing of yarn we will have different types of equipments. Like single yarn test,
single yarn strength we can test using instron or any other instrument. Also we can test at
very high speed which is known as tensorapid or tensojet. So if we see if we compare the
result, these results will be entirely different for a particular type of raw material.

So, for any material like even other parameters like, evenness also if we test the evenness, in
terms of say capacitance method. In capacitance method we will get one particular type of
evenness. But if we test in photo electric method, then the evenness value will be totally
different. So type of test equipment or principle of testing also affects the test results.

And test condition, as I have already mentioned speed, temperature, also pressure affects the
test results. Like you want to test the thickness of fabric, so to test the thickness of fabric we
must specify the pressure otherwise because textile material is compressible in nature. So, for
any standard test method, to test the pressure, thickness; pressure is actually specified. If we
do not follow this specified condition, you will land up with totally different results.
(Refer Slide Time: 18:58)
So, to minimize all these variations, we have discussed all the, variation; all the different
types of variation, all the causes of variation and to minimize these variations standard test
methods are followed. So, worldwide there are various standards, different countries they
have various standards, but they have specific format. Most of the test methods they follow
the specific formats. Like in India we follow BIS standard; Bureau of Indian standard.

So, in India we follow BIS standard, in Britain we follow BS standard British standard,
America ASTM standard, Germany DIN standard. So, different countries they have different
standards. But overall, internationally ISO standard is actually established and it is being
followed across the country. So, international Organization for Standardization, so all these
standards, they have specific formats.

And this format they tell detail about the testing and they are numbered. For a particular tests,
particular characteristics, they have different number. Like ASTM, they have for yarn, they
have different series of numbers; for fabrics they have different series of numbers. So, same
parameter when we refer BIS standard it will have different, number okay. But over all if we
see these standards are very close to each other. Okay.

And they have almost similar format. They, if you see the total format what are the
information what is the information available in the standard?
(Refer Slide Time: 21:14)
If we see, so general format and guidelines of this standards, any standards first it will be
scope of the test. It is given scope. There it is like scope of testing is the tensile testing of
yarn. That is the scope and there total scope of this method, particular method is described.
What type of yarn? What are the characteristics required everything is given their okay. Next
is that reference documents.

What are the documents you have to refer to actually test the material; to how to test the
material? So, there are different reference documents it has given there. Then different
terminologies, so there are different reference documents it has given there. Then different
terminologies, so for testing you must know the terminologies. Different terminologies you
have to know okay? So what is the strength, what is the elongation, different terminologies
related to that particular test?

Then broad overall summary of the test method in short so that if you do not want to read in
detail. So you just go through that summary you can test. Okay. You do not need to go to
detail test method there. Overall summary you can just come to know what are the test
methods has been described here. Next is the significance and use of the test. Okay. So, what
are the significance of the test?

Why do we want to test that particular characteristic? So, that significance and what are the
uses of this it is given there Then Apparatus; apparatus is mentioned. Particular company will
not be mentioned who are the manufactures will not be mentioned but overall apparatus is
mentioned because as we have already explained that the test result varies with the apparatus.
So, the apparatus an overall broad outline of the apparatus will be given. And that all these
apparatus has to actually follow these guidelines. So then only you will get the repeatable
results. So, the standard test methods idea is to that that wherever you test, if the material is
same you must get the same result. And it is not that that the test testing lab all the testing lab
will have the same apparatus.

It cannot happen. They will have to have from different manufacture. But these instruments
they have to follow that particular test method. They will actually the instrument
manufacturer will give will tell that this instrument follows, this standard okay, ASTM this
standard, ISO this standard that they will give. So that particular apparatus you have to
follow. Then only you will get the result.

Then comes how to sample? So for a particular material, particular type of test you have to
follow strict sampling method. So detailed sampling process we will discuss. But there they
will give you the strict sampling method. Because if you do not follow the proper sampling
method or test result will be totally different. Okay. Next is that how to Condition. So we
cannot start testing immediately after getting the material. No.

We have to condition the material. And there is specific conditioning temperature, humidity
or time is there. So that conditioning we have to follow strictly. Then comes, the procedure in
detail. So, earlier we have discussed that it is a summary of the test method. Then it is
procedure, detailed procedure, so person who does not know the test method, who is doing
for the first time.

If he reads the procedure he will just follow one by, step by step, and then he will be able to
test material. Because the different person, they are testing in a different lab. Okay. Same
material ultimately, ultimate goal is that from two labs, two different persons they are testing.
But their test result should be exactly same. That is the idea. So they have to follow this
procedure strictly line by line, word by word.

Then only we can reproduce the results and then how to calculate. We cannot calculate the
results as per our own wish. We have to follow their, own calculation like if you want to
know the mean, how many readings are required? All these details are given. Okay. Then
report. Report should be had a particular format. The, format is given, so that format we have
to fill the report.

So ultimately if we follow all these steps, so we must reach, we must get the same result. So
the standard method, standard test methods, the idea is to have that the same material should
give the same result. Okay. Otherwise if we do not follow, if we actually deviate little bit,
then we will have totally we will land up with total different results. And then we cannot
compare. And that is why for any test the requirement is that we must write this is as per this
test. Okay? Now we will see different
(Refer Slide Time: 27:36)

Standard terms related to testing. We must know these terms for actually after testing, we
actually we should correlate with these terms. So before we start testing we must know the
terms. First term is the quality. If you ask that what is quality. So normally, at the back of the
mind we know that quality means it should be best in behaviour, best in characteristics.
Actually that is not the quality.

Quality as per ISO it is stated that, Ensemble of properties and characteristics of a product or
a service quality of product can be also a quality of a service, which confer on it the capacity
to satisfy the expressed or implicit requirements. That means the expressed requirements;
means I need one yarn say I am giving example of yarn of strength say 10 gram per Tex. This
is the strength required. Now if I am producing, yarn, my requirement is ten.
Or customer they are paying for 10 gram per Tex. Suppose I am producing a yarn of 20
grams per tex double that; so should I be happy? It is not that. It is actually I am not actually
producing the quality. Quality does not mean that you have to produce the best one. It is a
requirement. So our requirement is that expressed requirement is that it is the 10 gram per
Tex. If I am producing say 9 gram per tex I am not producing the quality.

But if I am producing just 10 or just little bit above 10 then I am producing the quality
because I am meeting the expressed or implicit requirement that is the requirement. So that
characteristics of the product that is the requirement. Okay? And the capacity to satisfy the
requirement that means if I am producing 10 that means it is satisfying the requirements. If I
am producing the strength as of 20 it is also satisfying the quality.

But quality at certain cost, extra cost, my bag is not going to give me extra money for extra
strength. Okay? That 20 grams per Tex is actually it is for those customers who needs that.
So that is called suitable for use or fitness for use. That is the quality. So, in one word if you
trying to say the quality it is suitable for use it is not more than that or less than that.
(Refer Slide Time: 31:30)

Next is that testing we are going to discuss all about testing of textile material, evaluation of
textile material. But we must know what is testing? What is the term testing called? So it is a
means of determining the capability of an item to meet the specified requirement, just try to
understand that the capability of an item to meet the specified requirement. So to determine,
so I want to determine, whether this yarn will be able to achieve 10 gram per tex strength.
Okay? That is our requirement.
So I want to determine the capability of this yarn. So, how to determine the capability the
yarn? That determination is known as Testing. So, how to determine? By a set of physical,
chemical, environmental or operating actions and conditions; means if I want to know the
capability this yarn whether it is a 10 gram per Tex or not, I have to give the, some physical
action on this; I have to pull the yarn. Okay?

I Have to extend the yarn. I have to apply force to the yarn. These are the physical
characteristics. What is chemical? Suppose I want to know the blend percent. For blend
percent I want to calculate the blend percent by dissolving. So for that chemical activity is
required. Sometimes we need to know the environmental activity. Suppose I want to test the
change in colour, with the sun light fastness particular environmental condition I have to
expose the material.

So if we see the operating action; so you want to change the speed or any other things. So
testing is that basically to determine the capability of the material. Whether that material is
actually satisfying the required characteristics? By subjecting certain physical, chemical or
environmental condition so that is the overall testing. Okay? Next term is that Inspection.
(Refer Slide Time: 34:25)

Testing is that it is a very, very specific. I am testing the yarn for strength. But inspection is
overall. It is an area; It is volume is much bigger. Okay? It is much bigger; like it is a activity
such as measuring, examining, testing; testing is one of that. Okay. But I am trying to
examining, so 10 different lot. Okay. I am inspecting. So Inspection is I am testing the okay, I
am telling the okay. You would get the strength of this yarn okay.

Now, after that the whether; that this bobbin shape is okay or not? Whether that there is
damage is there or not? Okay? So all these things are taken together, it is called Inspection
and I am trying to compare whether this yarn is better than this yarn or not. So comparison;
so testing is one small aspect but inspection is overall so, the activities such as measuring,
examining, testing one or more characteristics of a product, at a time.

Suppose I want to know the overall characteristics. I want to inspect. Okay this yarn is okay it
is strong. This yarn is okay, there are very, very it is a dirty. It is not clean. There are foreign
matters. So this, all this overall, one or more characteristics we try to evaluate in one go
through inspection. Okay? And comparing this with the specified requirement to determine
the, the conformity whether this yarn confirms the total requirement, the inspection will tell
us.

Even in breakage study in the ring frame. It is not testing. So it is not necessary all the
component has to be there. Even say examining, I am examining that whether I am counting
the number of end breakages. Okay, per hour in a particular ring frame. And I am comparing
with the other ring frame or I am comparing with the standard. So it is called inspection. Like
we, have seen, we know that the buying house they come to the industry; garment industry,
they inspect.

They try to test; they try to take the sample randomly. They open the packet and try to see
whether and measure the dimension. It is inspection. Okay, so fabric inspection. So there are
different types of inspection. The advantage of inspection is that it is a quicker. It is a easy
quicker method to know overall characteristics.
(Refer Slide Time: 37:38)
Next is the term Quality Control. That is the very commonly used term Quality Control. It is
actually function of inspection; It is a function of inspection testing everything. Okay? The
operational technique and activities used to fulfil the requirement of quality. So we have the
required quality. We know this is the quality we have to achieve. Like let me give, take the
earlier example, our quality is that 10 gram per Tex. This is the quality achieved. So to
achieve this quality, to fulfil this requirement, we have to test the material, we have to inspect
the material it at every stages. And that is called Quality Control.

We must know to have this yarn we have, we need this much waste percentage, this much
trash percentage this is the length; so all this things, this is the function of say inspection,
testing or different aspects to achieve a required quality. Okay? Next term is called it is that
Statistical Quality Control. One is Quality Control and Statistical Quality Control, only
difference is that when we use Statistics in quality control it is called Statistical Quality
Control.

Like to use the application of statistical technique for quality control, like we have to know
mean, measure mean, so that is Statistical Quality Control. We are achieving this. We want to
know variability of the material. How much variation is there? Standard deviation, coefficient
of variation; we want to know whether this difference is significant or not. So we do
significance test. t test, F test. So this all these things are under statistical quality control.
(Refer Slide Time: 39:48)
And next is that Quality Assurance. So Quality Control we know. Then that Quality
Assurance; Quality Assurance is something broader. It is not, it does not talk about the
material only. It talks about the total, it, takes care of human resource, takes care of time
management. Okay? So motion study, time study everything. It is material characteristics is
one of them. It is a total system. And just to assure the quality. Okay.

So, all those planned or systematic actions necessary to provide adequate confidence so the
industry should have sufficient confidence that whatever I am producing, whatever we are
producing. It will give us, lead us to a particular quality. That much confidence has to ever.
So how do we get that confidence and that a product or service will satisfy the given
requirement for quality. So, again I am taking the same example.

This is our requirement 10 gram per Tex. Okay. And Quality Control we have achieved.
Okay. This is by testing we have achieved. But how do ensure how do the management
know? That okay, my industry, this industry, particular industry will always produce that type
of quality. That is the adequate confidence has to be there. For that we need to have
systematic plan. So how do we have systematic plan.

So this planned activity if we do, then we will be able to achieve the quality. So these are the
systematic achievement. Few examples are there. Like control of vendors for supply of raw
materials. This is particular quality I want to achieve. And I cannot go to market and take
randomly from different vendor because I do not have that much confidence. Based on our
previous experience, we have identified few vendors, two, three vendors, okay, who have
already supplied consistent quality, consistent quality of raw material, okay?

That vendor identification is very important. So first thing is we have to control the vendor
who supplies the raw materials, chemicals and all these things. And if we know that this
particular vendor will give me a consistent quality of raw material, consistent quality of
chemical then we are sure that okay I am getting raw material for a particular yarn or
particular end product. Next is that proper setting of the machine.

For that proper setting, proper maintenance schedule has to be there. So this, it is actually for
ISO 9000 or different types of Quality Assurance. There it is a written that it is the machine
setting for this particular yarn, this particular fibre. This is the roller pressure has to be there.
It is written and that the lab, that supervisor, that floor level supervisor, they have to follow
these things.

They do not have to do any other thing, only has to they have to follow these particular
setting, okay. We have to follow particular environmental condition. So it is specified for say
spinning shed, we need to for a cotton, we need particular environment, particular relative
humidity. For cotton we need different relative humidity, for polyester we need a different
relative humidity. Otherwise the machine running will be getting affected. Next is the Man
power training? Continuous Man power training has to be there. Human resource
development has to be there. Otherwise they will not be able to produce the required quality
of the product. That confidence will not be there. Okay and proper time management.

So, Time Management is very important. Suppose my buyer, he wants the material after one
month particular time okay? And if I am not able to supply that material within that specified
time, that means, the non conformity will be there and that, I am not actually supplying the
quality product. Quality here quality assurance does not mean the quality of material. Quality
of service will also be there. Okay?
(Refer Slide Time: 45:24)
Next is the Quality Management. Quality Management is that you understand your quality
okay you planned your quality. Then you have to manage that quality, you have to maintain
that quality. And after that you have to go for the improvement of the quality. You cannot
stick to that quality. Today you are producing quality grade D. Tomorrow you have to
produce grade C. Then grade B. Continuous improvement has to be there.

That is, so Quality Management does not aim to assure best quality always. So if I am
producing D grade yarn, I will tell this industry produces D grade yarn. Because for D grade
yarn D grade quality you will have different product, different buyers will be there for that, it
is not always target for the best quality by the more general definition, but rather to ensure
that an organization or product is consistent.

If I am producing B grade yarn, B grade quality it is consistent. So that, I am known for that.
And I will have that type of buyer. Okay. So it has got four components as I have mentioned.
First is, you have to plan your quality then Quality control, quality assurance and last is that
quality improvement. So today I am producing B grade quality. So tomorrow I will have
target, I will target to achieve the A grade target.

But till then till that time I have to be satisfied with that. I will tell this is my quality. I am not
targeting the best quality because for different quality you have different buyers. Okay?
Different users are there.
(Refer Slide Time: 47:27)
Now we have mentioned that for standard testing, for to get the standard test results, we need
to have standard testing atmosphere. So standard atmosphere is that in which the physical
tests of textile materials is performed so as textile materials are, most of the materials as I
have mentioned that hygroscopic in nature, and they are directly affected by the humidity and
temperature of environment.

So we must know and we must maintain the relative humidity and the temperature. So in cold
country, the standard, there are 2 different standards we follow. In cold country, the standard
is the relative humidity 65 +- 2 % and standard temperature is 20 +-2 degrees Celsius. This is
the cold country. And in tropical country or sub-tropical country it is a relative humidity is
same but temperature is 27 +- 2 degree Celsius.

So, that you do not have to go for too much air condition. Okay. So that is the reason. And we
must actually mention in any test result we must mention that this is tested under this
condition. Okay? Because if we test a cotton say under say 100% relative humidity and we
are telling okay this yarn is giving very good results. Then we are misleading so we because
the particular yarn and you have shipped the material.

You have actually, sold the material. Okay. But when your customer will test in under
standard condition, then you will land up with lower value. So we have to follow standard
test method. And we must mention that this is the standard.
(Refer Slide Time: 49:50)
Now we will see the overview of the course. The course overview that is what we are going
to discuss in the total entire course. Okay. First we will start with the sampling. So sampling
methods and sample size, we will start with the different sampling method and different
sample size to achieve certain confidence level. Okay? So in that, we will discuss the
meaning of sampling. What is sampling.

So all these things we will discuss here. Next is that we will discuss the aim of sampling.
Why do need to sample the material. Why do not you test the total material? So sampling,
aim of sampling we will discuss there. After that the different factors which governed the
sampling method so, we do not follow the same sampling method for say the fibre or if you
want to sample the fabric that we have to follow the different sampling method.

So, there are various factors which governed the sampling method. This we will discuss in his
part. Then there are different types of sampling; statistical sampling, non- statistical sampling
within statistical sampling, there are four different types of sampling. So all these techniques
we will discuss methods we will discuss with example. Here I will keep all, the example
related to textile materials okay. And different terms commonly used for sampling. So bulk
sample, consignment, lab sample. So these terms we will discuss. Methods we will discuss
with example.

Here I will keep all, the example related to textile materials okay. And different terms
commonly used for sampling. So bulk sample, consignment, lab sample so these terms we
will discuss and the meaning of these terms. So we must know these terms. And sampling
stages of textile materials at which, stage, different stages we sample so different stage like
fibre, at the stage of fibre, at the stage of bale.

So fibre testing also we can do at different stages. From bale we have, we can sample. From
sliver we can sample. Even from say carding machine we can sample. So but their techniques
will be different. So this we will discuss, different sampling techniques, then one concept is
there critical difference is there. Concept of critical difference we will discuss here.

Then fibre sampling from bulk so we have, we can, as we have mentioned that different type
of sampling. So from bulk, say from bale, we can sample. So, how to sample the fibres from
the bulk or from bale this sampling techniques we will discuss. Then fibre sampling from tuft
or sliver or roving, like this is sliver. If I want to sample from the sliver, it will be totally
different character then if we want to select from the loose.

Because in sliver, fibres are aligned and if we try to sample from the surface, from this point
or from the end, the ultimate result will be totally different. This I will discuss here in detail
okay. Then we will discuss the yarn sampling. Yarn sampling from fabric, Yarn sampling
from bobbing; how to sample the yarn? Even then from the cone, how to sample? So, we will
discuss. Then we will discuss the sampling of fabric. So fabric sampling will also discuss.

So all these sampling techniques we will discuss here. And fabric sampling is we will see
entirely different from, from the say yarn sampling, or fibre sampling. Then we will discuss
the how to determine the sample size. Say for yarn we want to test the strength. Okay. So
how many yarn sample do I take, 10, 20, 100, so there are statistical techniques to know the
sample size.

So we will discuss in detail the number of sample. Number of what is the sample size? This
we will discuss here with the numericals. And then we will discuss the test of significance.
Suppose we are sampling and the whether the sample is actually different from the
population, that significance test will be there. Suppose we have to change the certain
parameter.

By sampling technique we should be able to tell with certain confidence that this difference is
significant or this difference is not significant. That testing we will do. We will do different
numerical samples. And also a control charts which is very important for day to day mill
practice okay, where we have to take actual action or not okay.

And then we will discuss detail about the Practical Statistical based sampling. Okay. Practical
Statistics we have to see based on the sampling. So we will give various example and various
numerical we will do, based on the sampling, okay. And we will come to know, we will see
that T-test, F-Test, sampling of variation of, significance variation in mean, significant
variation in dispersion or we have, we can test the various parameters we will, for statistical
techniques we will discuss here. Next we will continue this things the course overview in
next class. Till then, Thank You.