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Theory and Calculation of Cover Factor of Woven Fabric
Ramandeep Singh
B.Tech, Dept. of Textile Engineering
Giani Zail Singh Punjab Technical University Campus,
Bathinda, Punjab, India
Email: rmnsandhu3335@gmail.com
Cover Factor:
Cover factor is a number that indicates the extent to which the area of a fabric is covered by one set of threads. For any woven fabric, there are two cover factors: a warp cover factor and a weft cover factor. Under the cotton system, the cover factor is the ratio of the number of threads per inch to the square root of the cotton yarn count.
d/p = relative cover,
(d x 100)/p = percentage cover
(d x 100)/p = percentage cover
It is preferable to express warp and weft relative cover separately, as the cumulative value of cloth cover does not indicate the comparative importance of each set of yarns which is essential for the determination of certain cloth characteristics.
From the relationship shown above it will be obvious that if d= p. the value of relative cover is one, and this is regarded as the theoretical maximum cover. In practice, however, this value can be exceeded considerably in any one direction, either through yarn distortion, or, by forcing the threads into different planes, especially if the relative cover of the opposite set of threads is reduced correspondingly.
The relative cover for one thread system can be calculated as follows by considering an area of 100 x 100mm:
Area per thread = 100 x d
Area covered by n threads of one system = n x 100 x d
Therefore, relative cover = (n x 100 x d)/(100 x 100) = (n x d)/100
Example: The cloth represented at A is specified as follows: Warp — 25 tex cotton, 267 ends/100 mm; weft—36 tex cotton, 334 picks/100 mm. Find the relative warp and weft cover. (Subscript 1 refers to warp, subscript 2 to weft.)
Warp relative cover = (n1 x d1)/100
= (267 x √(25)/(26.7))/100
= 0.50
Weft relative cover = (n2 x d2)/100
= (334 x √(36)/(26.7))/100
= 0.75
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