3. Testing
• The determination by technical means of properties;
performance; or elements of materials, products,
services, systems, or environments which involve
application of established scientific principles and
procedures.
• Critical examination of the quality, composition, or
properties of a material, usually involving
standardized test procedures.
• Technical operation that consists of the
determination of one or more characteristics of a
given product, process or service according to a
specified procedure.
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4. Quality
• An attribute, property, special feature.
• The nature, kind or character (of something); hence, the degree or
grade of excellence, etc. possessed by a thing.
• ISO 8402-1986 standard defines quality as "the totality of features and
characteristics of a product or service that bears its ability to satisfy
stated or implied needs’’.
• “Quality is about meeting the needs and expectations of customers”
• Quality means the customer satisfaction.
• Customers want quality that is appropriate to the price that they are
prepared to pay and the level of competition in the market.
• Key aspects of quality for the customer include:
Good design – looks and style
Good functionality – it does the job well
Reliable – acceptable level of breakdowns or failure
Consistency
Durable – lasts as long as it should
Good after sales service
Value for money
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5. Control
To check or verify, and hence to regulate. Without skilled and
experienced technologists ‘control’ loss its meaning actually.
Quality Control
• Quality control is the checking, verification, and regulation of
degree of excellence of an attribute or property of something
(textile).
• Properties such as linear density, evenness etc must be well
defined.
Quality in the textile trades might perhaps be defined as the
degree of conformity to a specification, the specification itself
having been drawn up with the object of providing an article
which has suitability for an end use. (Kenyon)
Quality control is a wide subject and covers all those factors
which help to ensure that the product produced is of desired
quality. (Newbery)
Newbery’s definition emphasis on factors where as Kenyon’s
definition says degree of conformity.
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6. • On Line Quality Control: On line quality
control occurred in the production line with
sensors and data systems. Such as,
determination of periodic variation of yarn,
determination of yarn hairiness etc.
• Off Line Quality Control: Off line quality
control occurred in the testing lab other
than production line. Such as yarn count
testing, fiber testing, gsm calculation etc.
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7.
8. I. Checking and Selection of raw material:
The incoming material is checked for the required
properties so that unsuitable material can be
rejected or appropriate adjustments made to the
production condition.
II. Monitoring Production:
Production monitoring involves testing samples
taken from the production line. Its aim is to
maintain, within known tolerances, certain specified
properties of the product at the level at which they
have been set. A quality product for this purposes is
defined as one whose properties meets or exceeds
the set specifications. This step can be termed as
process control.
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The Objectives of Quality Control
9. III. Assessing the final product:
In this process the bulk production is
examined before delivery to the customer to
see whether it meets the specification or not.
By default it is done after the material being
produced. It therefore can not alter the
production conditions.
In some cases selected samples are tested
and in other cases all the material is checked
and steps taken to rectify faults.
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10. IV. Investigation of faulty material:
Investigations of faults involve the
determination of which party is responsible
for faulty material in the case of a dispute
between a supplier and a user, especially
where processes such as finishing have been
undertaken by outside companies. Work of
this nature is often contracted out to
independent laboratories who are then able
to give an unbiased opinion.
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11. V. Product development and research
The results of testing in research help the researcher
to decide which rout to follow next, what appears to
be sound theory etc. In this way an improved
product or a lower-cost product with the same
properties can be provided for the customer.
VI. Process development
Process development may be considered as a form of
applied research. The experimental work may be
carried out by research institutes. Process
development offers higher profit with optimum
production and quality by reducing time and
manpower. The process development is carried out
through investigation into better, cheaper and
quicker methods of material conversion.
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12. VII. Specification tests
There has been a growing demand in recent years for
the production of textiles to meet specifications. The
advantages can be noted as i) prevention of
deterioration in quality using inferior raw materials,
ii) the production of goods of known performance
and iii) the opportunity for a manufacturer to be
informed exactly what is required by the customer.
The advantage from user point of view is that he can
set the specification that he really demands.
Specification test also save the manufacturer from
great loss by producing samples to meet the
specifications as per customer demands before going
to bulk production.
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13. VIII. Customer reputation
It is evident that some form of testing is required
at every stage of manufacture so that the finished
product will prove satisfactory to the buyer and
consumer. Consumer satisfaction enhance the
reputation of manufacturer which subsequently
lead to repeat orders and continued prosperity.
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14. The key factors to control quality
Quality and the Control of Quality are governed by 3 key
factors stated as 3 ‘M’s. Men, Materials and Machines.
• Men:
- Production level
- Maintenance and other levels
- Testing level
They require a technical know how on the job that they do,
how a sample is collected, which testing procedure will be
carried on, etc.
- Management level: A successful coordination of all the
operations, selection and training of man power. The
knowledge of properties of raw material for a particular
end product of desired quality. They must need sufficient
knowledge to interpret the data and which decision can be
made on test result.
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15. Materials:
- The selection of raw materials is a key factor in the
success or failure of quality of the next product. For
example, fiber determines 80% of quality of yarn.
- Materials must be possessed the relevant properties
with the final product. For example, long and finer
fiber needed for Combing process as well as finer
count.
- Alternative materials of consistent properties are
very useful when the preferred type is not either
available or too expensive. Substitution may be
accepted without seriously impairing the ‘degree of
excellence’ of the product.
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16. • Machine:
- All the conversions and testing are performed by
machines which must add or remove the quality
on products.
- The selection of best machine does not mean
that it produces best quality but optimum,
because increasing quality decreases the
production and increase the production cost.
- The machine which may be best from a technical
viewpoint but not be an economical proposition.
The availability of manpower can influence the
decision.
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17. The causes of variation of test results
• Variation in the material:
- Most textile materials are variable, natural
fibers having the most variation in the
properties.
- The problem of variable material can be
dealt with by the proper selection of
representative samples and the use of suitable
statistical methods to analyze the results.
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18. • Variation caused by the test method
- The influence of the operator on the test results
- The influence of specimen size on the test
results.
- The temperature and humidity conditions under
which the test is carried out.
- The type and make of equipments used in the
test.
- The conditions under which the testis carried
out such as the speed, pressure or duration of
any of the factors.
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19. Need of standardization
When material is bought or sold out side the
factory there are. Then two parties to the
transaction, both of whom may wish to test
the material. It therefore becomes important
in such cases that they both get the same
result from testing the same material.
Otherwise disputes would arise which could
not be resolved because each party was
essentially testing a different property. To
resolve this problem-
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20. - The test procedures used by more than one
organization have to be more care fully specified,
including, for instance, the temperature and
humidity levels at which the test takes place.
- The details description of the procedure have to
be sufficient so that equipment from different
manufacturers will produce the same results as
one another.
- The standard written test methods leads to the
setting up of national standards for test
procedures so making easier the buying and
selling of textiles within that country.
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21. - Most countries have their own standards
organizations for example: BS (British Standard),
ASTM(American Society for Testing and Materials)
standards etc
- The same arguments that are used to justify national
standards to assist world wide trade, hence the
existence of International Organization for
Standardization (ISO) test methods and, with in the
European Union, the drive to European standards.
- “Tested-Quality” plan is such a scheme that helps the
manufacturer, retailer and consumer to gain the
maximum satisfaction from textile. In this scheme,
tests are carried out depending on end uses. For
example, color fastness in sea water and chlorinated
water are tested for swimsuits. 21
22. Quality of testing Man
• Should have knowledge about the demand of
market.
• Should have proper technical knowledge and
skill to run the testing instrument.
• Should have idea about statistics for the
representation of testing results.
• Should have skill about application of result.
• Should have idea about development of
various technical matters.
Self study: Importance of textile testing.
23. Deming circle/cycle/wheel
PDCA (plan–do–check–
act or plan–do–check–
adjust) is an iterative
four-step management
method used in
business for the control
and continual
improvement of
processes and
products. It is also
known as the Deming
circle/cycle/wheel
24. Plan:
The planning phase involves assessing a current process, or a new process, and
figuring out how it can be improved upon. Knowing what types of outputs that are
desired helps to develop a plan to fix the process. It is often easier to plan smaller
changes during this phase of the plan so that they can be easily monitored and the
outputs are more predictable.
Do:
The do phase allows the plan from the previous step to be enacted. Small changes
are usually tested, and data is gathered to see how effective the change is..
Check:
During the check phase, the data and results gathered from the do phase are
evaluated. Data is compared to the expected outcomes to see any similarities and
differences. The testing process is also evaluated to see if there were any changes
from the original test created during the planning phase. If the data is placed in a
chart it can make it easier to see any trends if the PDCA cycle is conducted multiple
times. This helps to see what changes work better than others, and if said changes
can be improved as well.
Example: Gap analysis, or Appraisals
25. Act:
If the check phase shows that the plan phase which
was implemented in do phase is an improvement to
the prior standard (baseline), then that becomes
the new standard (baseline) for how the
organization should act going forward. Instead, if
the check phase shows that the plan phase which
was implemented in do phase is not an
improvement, then the existing standard (baseline)
will remain in place. In either case, if the check
phase showed something different than expected
(whether better or worse), then there is some more
learning to be done... and that will suggest
potential future PDCA cycles
26. Sampling
For research purposes, individual textile can be
selected for examination or testing. It is not
possible or desirable to test all the raw material
or all the final output from a production process
because of time and cost constraints. Because of
this, representative samples of the material are
tested. The amount of material that is actually
tested can represent a very small proportion of
the total output. It is therefore important that
this small sample should be truly representative
of the whole of the material.
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27. Types of sample
I. Biased Sample:
- Where a selection of an individual is influenced by factors
other than chance.
- The sample does not truly represent the bulk and the result is
biased sample result.
- Bias may be caused by physical properties (e.g. chance of
higher length of fiber in the sample), position of the sample (e.g.
yarn of outer layer from bobbin), position of the person as well
as subconsciously.
- The effect of bias on the test result may be negligible or not.
II. Random Sample:
- In this type of sample every individual in the population has an
equal chance of being included in it.
- The number of the sample must be sufficiently large to include
all the variations of the individuals in the population.
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28. Fiber sampling
Serial Sampling technique Scope
1. Squiring
Where the material is composed of parallel order e.g.
sliver, roving, yarn. (Numerical sampling gives a random
sample)
2. Cut Squiring
(modified squiring)
3. Zonning Raw cotton or wool (Random sample)
4. Dye Sampling From sliver and webs in which the fibers are entangled
(wool). (Random sample)
5. Tong Sampling For wool (extent biased sample)
6. Core Sampling From wool bale (for assessing the impurities)
7. Random Draw
method
Sliver, tops (numerical sample)
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29. Squaring Technique for Fiber
I. Squaring is a method that is applicable to slivers, rovings
or yarns in which the fibers are in a reasonably ordered
state and give a numerical sample.
II. A length of the yarn/sliver being tested is cut off and the
end untwisted by hand. The end is laid on a small black
velvet board and covered with a glass plate. The
untwisted end of the yarn is then cut about 5mm from
the edge of the plate as shown in figure.
III. All the fibers that project in front of the glass plate are
removed one by one with a pair of forceps and
discarded. By doing this all the cut fibers are removed,
leaving only fibers with their natural length.
IV. The glass plate is then moved back a few millimeters,
exposing more fiber ends. These are then removed one
by one and measured. 29
30. V. When these have all been measured the plate is
moved back again until a total of 50 fibers have
been measured. In each case once the plate has
been moved all projecting fiber ends must be
removed and measured.
VI. The repeat is essential because the fringe
formed at the broken edge of any fibrous strand
naturally contains a predominance of longer
fibers, and this initial bias can be eliminated
only in the manner described.
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32. Zonning Technique
Step-1: From the bulk a sample of about 2 oz is prepared by selecting about
eighty tufts from the bulk.
Step-2: Divide this sample into four quarters.
Step-3: Take sixteen small tufts at random from each quarter, size
approximately 20 mg.
Step-4: Each tuft should be halved four times, discarded alternately with right
and left hand and turning the tuft through at right angle between
successive halving. Sixteen wisps are thus produced from each quarter
into a tuft.
Step-5: Combine each set of wisps into a tuft.
Step-6: Mix each tuft in turn by doubling and drawing between the fingers.
Step-7: Divide each tuft into four parts.
Step-8: Obtain four new tufts by combining a part of each of the former tufts.
Step-9: Mix each new tuft again by doubling and drawing.
Step-10: Take a quarter from each tuft to make the final sample.
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34. Yarn Sampling
• Sampling for determination of Yarn Count
- Take sixteen packages (cops / roving bobbins / any
other primary packages).
- The skeins should be wound from the top portion
eight packages and from about half-way from
remaining eight.
- For the large packages such as cone/cheese, take
eight packages and wrap two skeins from each,
where one skein from outer portion and one skein
from inner portion.
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35. • Sampling for determination of Yarn Twist
- Take the test specimens in equal numbers from
ten packages.
- No specimen being taken from within 1 yard
length of the end of the package.
- Allow a minimum distance of 1 yd between
consecutive specimens
• Sampling for determination of Lea strength
- Take 20 packages from each of which a complete
lea may be withdrawn.
- If 20 packages are not available a smaller multiple
of four packages may be used.
- For e.g. eight packages, three leas from each of
four and two leas from each of other four
packages.
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