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Sunday, November 20, 2011

CALCULATION OF GSM

Learn Apparel Merchandising, Learn Fashion design.
Dear All,

GSM means the weight in gram per square meter of fabric.GSM is a very important parameter for specified a certain quality of knitted fabric. The production of knitted fabric is calculated in weight. The GSM cutter is very popular and easy usable GSM testing instrument used in most knitted factory. But the construction of this cutter is very simple. It is circular disk of 100 square cm area with sharp blade attached to its edge. So 100 square cm of fabric can easily cut by it and weighted at the electric balance to get GSM reading.


There are two formulas for calculating the GSM of a knitted fabric


First formula is as under:


               Course per inch X Stitch length X 39.37 X 39.37 X Tex
GSM =    ----------------------------------------------------------------------
                                               1000 X 1000

aNd

                WPI X CPI X SL(mm)
GSM =    ----------------------------- X 0.9155
                         Count(Ne)



CALCULATION OF WALES PER INCH (WPI):

We calculated the number of Wales in 10 inch fabric unraveling the yarn. Then we divide the no of total Wales by 10 inch to getting the Wales per inch.


CALCULATION OF COURSE PER INCH (CPI):

We calculated the number of course in five inch with the help of counting glass and needle. Then we divide the total no of course by five inch to getting the course per inch.


MEASUREMENT OF STITCH LENGTH (SL mm):

Stitch length is theoretically a single length of yarn which includes one needle loop and adjacent needle loops on either side of it. Loop exits in course in course length and it is that which influence fabric dimension and other properties including weight.

In order to determine the stitch length, we count 100 no Wales or stitch and count its length by hanging the yarn on the stitch counter. The reading is found in mm unit.



MEASUREMENT OF YARN COUNT:

We have fallowed a different way to find out the count of the yarn. At first we unravel a considerable no yarn from the fabric. Then we measured the total length of the yarn and measured the weight of that no of yarn. From these weights, we find out the count of the yarn.

The equation we followed is as follow:

                 N x L x 453.6
Count =   ----------------
                 Wt x 36 x 840
Where,

N   = number of yarn in bundle.
L    = length of yarn.
Wt  = weight of yarn.




Another formula is the following:

                    Ks x Tex
GSM =   ---------------------
              Stitch length (mm)


Where,
Ks is a constant. Its value is different for different fabric structure and fabric type. Ks is calculated and estimated as below:

              GSM x Stitch length
Ks =     -----------------------------
                          Tex


















(Collected & Edited)

Thanks & best regards
Bipul