Cotton yarn count by Knowles Balance
Yarn count: The count of a yarn is a numerical expression which defines its fineness. It means, by yarn count we come to learn about the thinness or thickness of a fibre or yarn.
The count of the yarn is the number of such yarns which are required to form one strand of a three – strand 3 in circumference rope.
Count is the number of ‘unit length’ per ‘unit weight’ i.e. unit length/unit weight.
The number of hanks (840 yds) per pound.
Warp reel to Knowles balance:
Knowles balance is a special direct reading balance behind which a separate rod of hexagonal section with five of the faces lettered from A to E and engraved with beam a small lettered rider.
Suppose a cotton yarn is to be tested and is judged to be about 36s. Face B of the scale is turned to the front, weight B is placed in the left – hand pan, and rider B put on the beam. The position of the rider is then adjusted until the beam is balanced and the count read off directly from the scale , the value taken opposite a line in the middle of the rider. The Knowles balance can, of course be designed to suit count systems other than that of cotton.
Standard Deviation to coefficient of variation: –
The standard deviation is the square root of the mean of the squares of the deviations of the observations from their mean, i.e.
- Warp reel.
- Knowles balance.
- Cotton package.
Atmospheric condition: –
- Wet condition: -26 ° c.
- Dry condition: -30° c.
- Difference between wet and dry bulb = 30° c-26 ° c. = 4° c
- So, relative humidity (RH) = 70 %
First of all we have to take a suitable package i.e. cheese or cone form of the yarn from which the yarn have to warp to the reel. Then the yarn was fixed in the screw of the reel passing through the yarn guide. The diameter of the reel is 54 inch. So if we want to take 120yds of the yarn we have to rotate the reel for 80 times & the gauge as well as the warning bell indicate the point of start & finished. Then the yarn was taken off by releasing it from the reel & a knot was given to it so that no yarn can removed & form a dense mass of cotton. At last the weight of the cotton yarn was taken with the help of the Knowles balance. The position of the rider is then adjusted until the beam is balanced and the count read off directly from the scale, the value taken opposite a line in the middle of the rider. Now repeat this procedure for ten times and put them on the table for calculating the average count, S.D & C.V%
Experimental Data: –
|No of the observations||Length of the sample yrds||Count from Knowles Balance(Ne)||Average Count Ne||S.D
- English (Ne): 20.45
- Standard Deviation: 0.4716
- Coefficient of variation: 2.31%
By this method we can easily defined the count of the yarn. The Knowles balance in our lab is not an air tight condition so the weight of the yarn is not appropriate for the movement of the air.