GSM of Woven and Knit Fabric

Theory

GSM of a fabric, also known as grams per square meter, is simply the metric measurement of the weight of a fabric. This measurement helps one to decide on the best weight to buy, considering the usage of the material at hand. The fabric GSM is directly proportional to the thickness increases as well. The factors of GSM are affected by yarn count, EPI, PPI, and different types of finishes and ingredients. First, GSM value is dependent on the kind of fabric like cotton, wool, polyester, etc.

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Objectives

To know about GSM
To know about the procedure for measuring GSM
To know about GSM cutter
Learn about factors that affect GSM
To know about the effects of GSM on fabric.

Working Principle

Normally, the area of a round GSM cutter is 1/100 square meters. So, multiply the average weight of the swatches by 100 to calculate the GSM of the sample fabric. The GSM is expressed by gm/m² and sometimes oz/yd². The calculation of GSM for woven and knit fabric uses the following method.

Weight per square meter = (Weight of sample in gm / Area of sample in cm²) ✕ 100

Machine Description

GSM cutter: The GSM cutter is a textile testing instrument that is used for measuring fabric GSM with the aid of a weighing scale and GSM pad. The GSM cutter is a circular fabric cutter or sample fabric cutter.

With this instrument, a uniform circular fabric is cut. The area of the fabric specimen cut by the GSM cutter is 100 square centimeters. The instrument is equipped with a set of four replaceable blades and normal cutting pads. The depth of cutting is up to 5 mm. The GSM cutter is used in consumer textile testing labs, mills, and in fabric stores of the garments factory and fabric retail stores.

Electronic balance: The electronic balance or an analytical balance is a class designed for measuring a small mass in the sub-milligram range. The measuring pan of an analytical balance is placed inside a transparent enclosure with doors so that dust does not come in and any air currents in the room do not affect the balance's operation. It collects and shows data by using power, on its screen. The enclosed box-shaped part is called the draft shield. It gives quick readings with high accuracy in a laboratory.

Apparatus

GSM cutter
GSM pad
Electronic balance etc.

Working Procedure

Taken a sample of fabric from bulk.
The fabric is placed on a GSM cutter pad.
Observe the fabric (no crease or crinkle is formed).
Then cut the fabric with a GSM cutter.
Taken as the weight of the fabric, which is cut.
Multiply the result by 100.
Repeat the procedure 5 times, taking samples from different places of the fabric.
Calculate the average value.
Calculated SD and CV%.

Atmosphere Condition

Dry bulb – 26℃

Dry bulb – 25℃

So, from the chart relative humidity – 92%

Sample of Fabrics

GSM Measuring Fabric Samples

Data and Tables

Table 1: Average GSM of Knit Fabric

Observed no	Fabric type	Sample weight	GSM X	Average GSM x	(X - x)	(X - x)²
1	Knit	1.673	167.3		1.28	1.638
2		1.706	170.6		4.58	20.976
3		1.671	167.1	166.02	1.08	1.1664
4		1.672	167.2		1.18	1.3924
5		1.580	158.0		-8.02	64.32
						∑(X - x)² =89.49

Table 2: Average GSM of Woven Fabric

Observed no	Fabric type	Sample weight	GSM X	Average GSM x	(X - x)	(X - x)²
1	Woven	4.134	413.4		5.38	28.94
2		4.069	406.9		-1.12	1.254
3		4.106	410.6	408.02	2.58	6.656
4		4.055	405.5		-2.52	6.3504
5		4.037	403.7		-4.32	18.66
						∑(X - x)² =61.89

Calculation

SD and CV of GSM

Results

The average GSM of woven fabric is 408.02 gm/m²

and the average GSM of knit fabric is 166.02 gm/m²

Conclusion

GSM is an important term in the textile sector. Fabric construction is dependent on this. Moreover, the quality of the fabric is dependent on it. Here, the CV% of the knit sample is 2.54% and the woven sample is 0.862%. So, the more accurate values are taken from the woven sample.

How stitch density calculated?

Ahmedabad