Textile Testing

 

Introduction to testing

 

To those engaged in the production, distribution and consumption of textiles, testing can be a valuable aid provided that the instruments and techniques are used effectively. When tests are made the results must be studied carefully so that the right course of action may be taken. Testing instruments cannot make decisions, and in the end some person has to interrupt the data and issue the necessary instructions for future action. Testing is, therefore, a means to an end and not an end in itself. The fact that a material has been tested, no matter how accurately, does not enhance its technical quality.

 

Because testing has to be paid for, it is essential that the persons carrying out the tests are competent and technically qualified. Good advice to anyone who is considering the provision of a mill-testing laboratory is to engage a first –class textile technologist. The man in charge of a mill-testing laboratory must be part scientist, part statistician, part technologist, and part diplomat. His technical ability will enable him to direct the various testing schemes and to keep abreast of new developments in processing, testing instruments, and techniques. Diplomacy will be required when he has to “put over” his findings to his colleagues both at management level and on the mill floor. This particular quality of the technologist is especially valuable when the results are unfavourable or when, perhaps, they highlight somebody’s mistake.

 

It has been said that the subject of textile testing can be covered by answering the ‘W’ questions: Why do we test? What do we test? When do we test? Who does the test?

 

Reasons for textile testing:

 

The testing of textile is an expensive business. A laboratory has to be set up and furnished with a range of test equipments. Trained operatives have to be employed whose salaries have to be paid throughout the year, not just when result are required. Moreover all these costs are non productive and therefore add to the final cost of the product. Therefore it is important that testing is not undertaken without adding some benefit to the final product.

 

There are a number of points in the production cycle where testing may be carried out to improve the product or to prevent sub-standard merchandise progressing further in the cycle.

 

1. Checking raw materials:

 

The production cycle as far as testing is concerned starts with the delivery of raw material. If the material is incorrect of sub-standard then it is impossible to produce the required quality of final product.

 

The textile industry consists of a number of separate processes such as natural fiber production, man-made fiber extrusion, wool scouring, yarn spinning, weaving, dyeing and finishing, knitting, garment manufacture and production of household and technical products. These process are very often carried out in separate establishments, therefore what is considered to be a raw material depends on the stage in processing at which the testing takes place. It can be either the raw fiber for a spinner, the yarn for a weaver or the finished fabric for a garment maker. The incoming material is checked for the required properties so that unsuitable material can be rejected or appropriate adjustments made to the production conditions. The standards that the raw material has to meet must be set at a realistic level. If the standards are set too high then material will be rejected that is good enough for the end use, and if they are set too low then large amount of inferior material will go forward into production.

 

2. Monitoring production:

 

Production monitoring, which involves testing samples taken from the production line, is known as quality control. 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 these purposes is defined as one whose properties meets or exceeds the set specifications.

 

Besides the need to carry out the tests correctly, successful monitoring of production also requires the careful design of appropriate sampling procedures and the use of statistical analysis to make sense of the results.

 

 

3. Assessing the final product:

 

In this process the bulk production is examined before delivery to the customer to see if it meets the specifications. By its nature this takes place after the material has been produced. It is therefore too late to 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. For instance some qualities of fabric are inspected for faulty places which are then mended by skilled operatives; this is a normal part of the process and the material would be dispatched as first quality.

 

4. Investigation of faulty material:

 

If faulty material is discovered either at final inspection or through a customer complaint it is important that the cause is isolated. This enables steps to be taken to eliminate faulty production in future and so provide a better quality product. Investigations of faults can also 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.

 

5. Product development and research:

 

In the textile industry technology is changing all the time, bringing modified materials or different methods of production. Before any modified product reaches the market place it is necessary to test the material to check that the properties have been improved or have not been degraded by faster production methods. In this way an improved product or a lower-cost product with the same properties can be provided for the customer. A large organization will often have a separate department to carry out research and development; otherwise it is part of the normal duties of the testing department.