Terms and Definitions of Textile Testing and Quality Control
Generally textile people like to speak in their own language. Like as different branches of textile, in the field of textile testing and quality control are also used different types of terms and definition. Those terms are frequently used during working oftextile testing. Besides, in interview board, a lot of basic questions have faced by the job seekers related with different terms and definitions of textile testing. Unfortunately, there are so many who cannot deliver the right answer of those due to lack of basic textile knowledge. In this article I will discuss different important terms and definitions those are used in textile testing.
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| Fig: Textile testing |
Population:
It is the total set of items defined by some characteristics of those items. For example, Doff weight of 60S yarn in a ring frame.
Sample:
It refers to any finite set of items drawn from the population. For example, 5 cops drawn from the Doff of a frame.
Random sample:
It is a sample from given population each clement of which has got equal chance of being drawn from the population.
Frequency distribution:
It is constructed from minimum of 40 readings to 100 and 200 items. Mode and media are not commonly used in textile industry.
Attribute:
Any selected quality or characteristic (that is present or absent in each of the units) that has to be statistically treated and judged is known as an attribute.
Variate:
It is the particular quality whose actual magnitude of character is measured from different units; for example, the weight of a group of units. The quantity which varies (height, weight, income, etc.) is called the variate.
Variability:
It is the variation of test results about a central value. Amongst the variables there are continuous as well as discontinuous variables.
Dispersion:
It is almost the same as variability.
AQL:
Acceptance Quality Limit
Scatter:
Like dispersion scatter also means variability.
Crocking:
Color is fading after rubbing from dry or wet cloth.
Frequency:
It is the number of times a particular characteristic occurs in a given sample or during a set interval, etc., which also implies the number of observations lying between two specified limits.
Frequency distribution:
It is the complete range of data arranged in a table of frequencies.
Frequency polygon:
It is the frequency distribution of a sample or population represented by a graphical method.
Histogram:
It is a grouped frequency distributed when represented by a series of rectangles side by side. This is an alternative method of diagrammatic representation.
Frequency curve:
It is a smooth curve obtained from a histogram, when the number of observations becomes very large.
Mean:
It is the same as usual arithmetic average where the sum of observations is divided by the number of observations.
Deviation:
It statistically implies the difference between an observation and the mean of all observations.
Median:
It is the middle value of a set of test values. The no. of test values greater than and lesser than are same. The observations are usually arranged in an increasing order.
Mean deviation:
It is obtained when the sum of all the differences of the values from their mean, taken without regard to sign, is divided by the number of values. This mean deviation is a measure of the spread.
Range:
It is the difference between the maximum and minimum values in a set of data and is the simplest measure of spread.
Variance:
It is the square of all deviation (all signs become +ve) and their mean (i.e. the mean of all squared deviations) or in other words it is the squared standard deviation.
Standard deviation:
It is defined as the root mean square deviation of numbers from their average. Square root of variance is also same as standard deviation and this is a useful tool in statistical results. The commonly used notations are Σ (sigma) or δ(delta) or by SD. The SD for a population is the square root of the average of the squares of the deviations by one less than the numbers of observations before taking the square root. This is an essential step in the condensation of data. In other words, the SD is a measure of the amount of variation I from the average of a set of data.
Estimate:
It is a value calculated from a sample to appraise a characteristic of the population.
Mode:
It is that particular value which occurs most frequently in a set of data.
Coefficient of variation:
It is a very useful tool in statistical studies and is usually denoted by CV. It is obtained when standard deviation is expressed as a percentage of the mean. CV is usually employed to compare the relative variations in different sets of data. Thus the CV is a measure of the relative dispersion and is useful in comparing the dispersions of two or more processes or materials or in comparing the same types of materials produced at different times.
Control chart:
It is a chart that is prepared to detect abnormalities and displaying the results.
Correlation:
It shows the interdependence of two variables.
Limits of variation:
It is the range within which all hut a specified small proportion of the values fall.
Tolerance limit:
It is the permissible limit of variation.
Percentage mean deviation:
It is a deviation expressed as a percentage of the mean and is denoted by PMD.
References:
- Mechanics and Calculations of Textile Machinery by N. Gokarneshan, B. Varadarajan and C. B. Senthil Kumar
- http://textilelearner.blogspot.com/2014/11/essential-garment-terms-and-definition.html
- https://textilechapter.blogspot.com/2017/02/textile-terms-definitions.html
