Cotton yarn count by Wrap Reel & 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.
Here again there are various units of length and weight and numerous systems. Generalising:
- N = the yarn number or count,
- W = the weight of the sample at the official regain in the units of the system.
- w = the unit of weight of the system (1 lb = 453.6 gm).
- L = the length of the sample (120 yds), and
- l = the ‘unit of length’ of the system (840yds).
The number of hanks (840 yds) per pound.
Wrap Reel :
Yarn in package form. Where the yarn is in package form, such as ring bobbins or cones, it is usual to wind a number of skeins by means of a wrap reel. This is a simple machine consisting of a reel, yarn package creel, a yarn guide which gas a small sideways traverse to spread the loops of yarn, a length indicator, and a warning bell.
The wrap reel may be hand – or motor driven and some are fitted with yarn –tensioning devices. For cotton yarns the reel has a girth of 54 inch i.e. yds, so that eighty revolutions of the reel produces a skein of 120 yd, or a lea. The reel girth and the skein length are chosen to suit the section of the trade concerned, 1 m reel girth for metric systems 36 inch. for worsted , etc.
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.
- Wrap Reel.
- Yarn 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 %
A first check should be to make sure that the girth of the reel is, in fact, 54 in, 1 m. or 36 in. Inaccurate reels are not unknown and it was conical, being more than 54 in at the back and less than 54 in. at the front.
Because yarns possess extensibility, it follows that the tension at which the skein is wrapped will affect the result – a high tension will produce a skein of ‘120’ yd which will be too light in weight and the calculated count will be on the fine side. A skein gauge can be used to check that the reeling tension is correct.
Experimental Data: –
|No of exp||Length L||Weight W||N||Count in Tex||Avg.|
By this method we can easily defined the count of the yarn. The Wrap Reel 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.