Textile Fractional cover and Cover factor (with its derivation)

Cover factor is a logical estimation of the percentage area of the fabric covered by the yarns and fiber. 

d = diameter

d/2 = radius

Fractional cover = d/p

Assumption :-

1. Diameter of yarn is uniform (i.e circular in cross section.)

2. Maximum cover factor is 28.

3. Yarn are lying in same plane

Fractional cover = Area covered by yarn /total area

d = 1/28√Ne 

p = 1/N

F.C = (1/28√ne ) X (1/N)

F.C = N/28√Ne

F.C X 28 = N / Ne

Where,

N = Threads per inch

Ne = English count

d = p

Cover factor = 28 and Fractional cover = 1

It means two parallel yarns  are touching each other.

Cover factor expression in S.I unit

KSi = n X √ Nf X 10⁻¹

Where,

N= Threads per cm

Nf = Yarn count in Tex