Textile Testing and Quality Control
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The document discusses different aspects of sampling including defining a population and sample, and describing two main sampling methods - random and biased sampling. It also outlines factors that affect sampling methods and different techniques for sampling different textile materials like fibers, yarns, and fabrics. Sampling aims to select a representative subset of a population for testing purposes. The key methods are random, which gives each item an equal chance of selection, and biased, where external factors influence the selection.
Textile Testing and Quality Control
- 1. Sampling Population: The whole bulk of the material available for testing is termed as population. Sample: The sample is a relatively small number of individual members which is selected to represent that population. A sample must consist of a number of individual. An individual is one member of the population. Sampling: Selection of material from the whole bulk for testing. There are two types of sampling methods- 1) Random sampling: -A method of selecting the individual where every individual of a sample in the population has an equal chance of being selected. -the number of sample must be sufficiently large to include all variation of the individuals in the population.
- 2. Sampling 2) Biased sampling method: In biased sampling method, the selection of an individual is influenced by factors other than chance. Hence the sample does not truly represent the bulk. Depending on the position of the sampling person. Factors affecting sampling methods: The form of the material Amount of material available Nature of the test Type of testing instrument Information required Degree of accuracy required
- 3. Sampling Sampling methods for different textile materials: Sampling for the determination of fiber properties Sampling methods for yarn Sampling methods for fabric Sampling for the determination of fibre properties: It depends upon the form in which the fibre is available. Different techniques for different form of fibres- Fibres in bale Fibres in sliver Fibres in yarn etc
- 4. Sampling Some techniques / methods involved for sampling fibres- The squaring technique The cut squaring method The zoning technique (for raw cotton) Dye sampling method (for wool) The tong sampling method (for wool) Core sampling method (for wool)
- 5. Sampling Sampling methods for yarn : Samples are randomly selected by various methods which differ according to the tests required. Sampling for the determination of yarn count (yarn from different packages) Sampling for the determination of yarn count (yarn removed from fabric) Sampling for the determination of yarn twist (yarn from packages) Sampling for the determination of lea strength of spun yarn Sampling for the determination of single thread tensile test (from any yarn package or from any woven/knitted fabric)
- 6. Sampling Sampling methods for fabric : Points of consideration while sampling fabric: Fabric within 2 inches of the selvedge should not be used. (Tension variation/strain on the yarns has effects)No two samples should contain the same threads Form (narrow/wide) & amount of fabric available for testing