What is Textile Testing?
Textile testing is the process of performing a series of tests of evaluating and assessing the quality, performance and properties of textile materials and products. It is an essential step in the textile industry to ensure that textiles meet specific standards, regulations, and customer requirements.
Textile testing is a key in gauging product quality, ensuring regulatory compliance and assessing the performance of textile materials. It is a vital basic tool during the processing of a textile raw material into the product. It also helps the distributors and consumer to determine the end product’s quality. It can include the analysis of the property of a known or an unknown material. So, textile testing refers to the procedures adopted to determine quality throughout the textile product chain (textile fibres, yarns and materials etc). It can be summarized as the application of engineering facts and science to determine the quality and properties of a textile product. Mainly it involves the use of techniques, tools, instruments and machines in the lab for the evaluation of the properties of these different forms of textiles.
So we can define textile testing in the following way,
Applying engineering knowledge and science to detect the criteria and properties of any textile material or product (such as fibre, yarn, fabric) is called textile testing.
Objectives of Textile Testing:
The main objective of textile testing are:
- To check the quality and suitability of raw material
- To monitor the production (process control)
- To assess the quality of final product
- To investigate the faulty materials
- To set standards or benchmarks
- For R&D (research and development) purpose
- For new product development
We can elaborate objectives of textile testing in the following ways:
- For researchers, testing results aid the development of new products or new processes, which can save money and resources before production starts on an industrial scale. They also help in the choosing of the best possible route to achieve the end product.
- Testing helps in the selection of the best possible raw materials. “Raw material” is a relative term; for example, fiber is the raw material for spinning, and yarn is the raw material for weaving.
- Testing helps in the process control through the use of advanced textile process-control techniques.
- Testing ensures the right product is shipped to the consumer or customer and that the product meets the customer specifications.
Testing in general, and textile testing in particular, is affected by the following factors:
Atmospheric conditions affect test results as textile products are greatly influenced by moisture and humidity. The test method adopted will also cause variation in test results. The testing instrument is also a vital part and, if not properly calibrated, can cause serious variation. Human error is another source of variation.
Textile testing starts with textile fibers and goes all the way through to the final product. The fiber test includes the length, strength, elongation, fineness, and maturity. The yarn test includes linear density, single yarn strength, yarn evenness, and yarn hairiness. The fabric test includes aerial density, weave type, and air permeability.
In order to carry out the testing of the textile products, a well-equipped laboratory with a wide range of testing equipment is needed. Well-trained operators are also a prerequisite for the running of the laboratory. The cost of establishing and running the lab is nonproductive and is added to the cost of the final product. These nonproductive costs increase the cost of the final product and therefore make it an expensive trade. Therefore, it is vital that testing is not performed without accumulation of some payback to the end product. Testing is carried out at a number of points in a production cycle to improve the quality of the product.
Types of Textile Testing:
Textile testing can be classified according to the basic technique used and on the basis of the data obtained. The former can be divided into destructive and nondestructive testing, the latter being defined as the application of noninvasive methods to reach a conclusion as to the quality of a material, process, or product. In other words, it is inspection or measurement without doing damage to the test specimen. Examples include drape testing and assessment based on the Kawabata evaluation system. Destructive testing is performed to test for failure of the sample. This type of test is much easier to perform and yield precise information and is more simple to understand than nondestructive testing. Examples of destructive testing are tensile testing and tear testing.
On the basis of data obtained, testing can be classified into objective and subjective. The former can be defined as the testing that gives us quantitative data, which can be easily further processed and interpreted. Subjective testing can be defined as that which gives us qualitative data, which is difficult to interpret and is greatly influenced by operator bias.
Importance of Textile Testing:
Textile testing helps to the manufacturers, retailers, and consumers make informed decisions about the suitability and durability of textile products. Principle importance of textile testing are;
- To ensure the product quality
- To control the manufacturing process
- For customer satisfaction and retention
- Good reputation (brand image) among consumers
Testing importantly supports the personnel involved in the textile supply chain, from the textile fiber to the end product. The testing of textile products aids persons involved in the running of the production line.
During testing, the discrepancy of the product, for example, its strength, maturity, waste percentage (for fibers), aerial density, and weave design (for fabrics), is properly measured. Thus the selection of the proper raw material is an important factor. Standards of control should be maintained to reduce waste, minimize price, and so on. Faulty machine parts or improper maintenance of the machines can be easily detected with the help of textile testing. Improved, less costly, and faster protocols can be developed by researchers with the aid of testing. The efficiency and quality of the product can also be enhanced with the help of regular and periodic testing.
Customer satisfaction and loyalty can also be won by producing according to customer specification in good time. In short, testing is an essential pivot to the whole textile product supply chain.
The cycle of testing starts with the arrival of raw material and continues up to delivery of the final product. The production of the required end quality is impossible if the raw material is incorrect. The textile product supply chain comprises different processes, which include the raw material (natural or man-made fiber), yarn manufacturing, fabric manufacturing, textile processing, and apparel and home furnishing manufacturing. It also includes some industrial products, like ropes, cords, and conveyer belts. All the aforementioned processes are performed in separate units or in a single unit if the establishment is a vertical production unit.
So the raw material for a spinning unit is fiber, for a weaving unit is yarn, for a textile processing unit is greige fabric, and so on. “Raw material” is a relative term that depends upon the further process for which it is used. Its testing is an important step, as improper raw material or low grade raw material will not yield the required quality of the end product. The testing of raw material is also performed to verify whether the incoming material accords with the trade agreement. Its consignment is therefore accepted or rejected on the basis of test results. The agreed specifications should be realistic so that the incoming raw material properties can meet the required level easily.
Production monitoring involves the testing of production line samples, which is termed “quality control.” Its purpose is to sustain certain definite properties of the end product within acceptable tolerance limits as per the agreement between the producer and the consumer. A product that does not meet the already agreed specification or the required quality will be termed a “fail.”
The proper testing protocol as well as proper monitoring are also required. The sampling techniques in use should also be selected properly, since the wrong selection could lead to serious problems. At the same time, the statistical tool employed is also an important factor. The collection of data is one thing, but its proper evaluation and interpretation, and the action taken on the basis of it, is an important factor in quality control.
Textile testing is vital to identify the particular cause of that fault so that it can be avoided in future consignments. It will also help to rectify the running process and enable it to run more smoothly so that the final product accords with the customer’s requirement. It also helps to isolate the faulty part or machine so as to resolve any dispute between the supplier and the producer.
Importance of Standards:
The tested textile materials should satisfy certain specifications. Some of these requirements are implicit and others are explicit. The latter are those that indicate a material’s performance in service or whether it will meet its specifications or not.
The implicit requirement is that the test is repeatable, that is the textile material will give the same results if it is tested again after some time by another technician or at some other place or the customer’s laboratory. In other words the test can measure the correct value of the property being assessed. There is no use in testing if it is not reproducible, as it will then count for nothing.
A lack of reproducibility of results can be attributed to the following. Textile materials have natural variation, for example, fibers obtained from a natural source have variation among their properties. In the material process from fiber to yarn to fabric, the variations in properties smooth out during the assembly of small variable units into large units. The problem of material variation can be rectified with the help of the proper selection of raw material and the use of appropriate statistical tools while analyzing and interpreting the data thus obtained. It is important to minimize the variations caused by the test method.
The possible reasons for variations caused by the test method are:
1. The technician has significant influence on the result. This is attributed to human error, human negligence, and not following the proper testing protocols. The preparation of the test specimen, the use of the proper instrument, the placement of the specimen on the testing machine, the noting of the value, and the adjusting of the scale properly are all sources of these types of variations.
2. An improper specimen size will also give an inaccurate result. For example, the length of the specimen in the case of tensile testing will affect the strength value of the specimen. So a change in specimen size will cause variation in the test results.
3. Atmospheric conditions are a very important factor when checking natural fibers. Fibers like cotton, viscose, and wool are greatly affected by changes in temperature and relative humidity. The results will show variation if conditions are changed while the test is being performed. The proper conditioning of the test specimen and the laboratory needs to adhere to specific parameters.
4. The use of proper test protocols is necessary to minimize variation. Pilling can be checked by a pilling box as well by the “Martindale abrasion tester.” The results obtained from the two types of testing equipment will not be comparable, as the methods involved are different, resulting in a variation of results.
5. The parameters used to perform tests, such as the speed of the machine or the pressure applied, will affect the final results. When these change, the results will also be changed. It is therefore necessary to lay down the conditions of a test and the specific dimensions of the specimen, and also to define a test procedure that minimizes operator variability, even within a single organization.
In the case of the selling and buying of the product, it is important that both parties will get the same results when they test the same material. Disputes may arise due to the improper testing of the end product, which can lead to severe legal action or the cancelation of the sale agreement.
Testing Methods (Sources of testing standards):
Testing is done primarily to test the quality and there are different ways to carry out a test. Sometimes, different principles and instruments may be employed to test a single criterion. Hence it is important to standardize the testing methods or procedures. Various national and international organizations have established standards for textile testing. Some of the organizations involved in developing textile testing standards are as follows:
- AATCC – American Association of Textile Chemists and Colorists
- ASTM – American Society for Testing and Materials
- ANSI – American National Standards Institute
- ISO – International Organization for Standardization
- BSI – British Standards Institute
What is Sampling and Sampling Techniques:
The aim of sampling is to produce an unbiased sample in which the proportions of, for instance, the different fiber lengths in the sample are the same as those in the bulk. Or to put it another way, each fiber in the bale should have an equal chance of being chosen for the sample.
The sampling method used to select a fiber for testing depends upon the form in which the fiber is available. We have published another article on sampling techniques.
- Advanced Textile Testing Techniques by Sheraz Ahmad, Abher Rasheed, Ali Afzal, Faheem Ahmad
- A Practical Guide to Textile Testing by K. Amutha
- Handbook of Textile Testing and Quality Control by Elliot B. Grover and D.S. Hamby
- Physical testing of textiles by B P Saville
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