The strength of a fabric gives us an idea how much load we can apply on it and it is very important for fabric. The strength of the fabric is very necessary for it because if the fabric strength is not good then it will break with excessive tensile force and thus the dresses produced may tear with the outside force. The strength of a fabric varies with EPI, PPI, and Count Variation. The strength of the fabric also varies if the length and width of the fabric to be tested is changed. The strength of the fabric also depends on the construction of the fabric. A plain fabric is stronger than a twill fabric if made from yarn of same count. The m/c used here is a vertical strength tester.

Objects:

To compare among the different fabric with standard value.
To know about the Vertical Strength Tester.
To measure the deviation of the result with the standard value and to produce the required fabric as per buyer specification.
To determine the fabric strength.
To know the fabric quality.
To know the mechanism of the machine used.

Theory:

Strength is a measure of the steady force necessary to break a material and is measured in pound. The m/c works in Pendulum lever principle with constant rate of extension. Assuming the specimen to be extensible and an absence of any dynamic effects, we get from the figure:

Fr = Mgr = MgRsinθ

As the value of M,g,R and r are constant, therefore

F ∞ sin θ.

According to the applied force the m/c dial gives us the strength in lb on the basis of this θ.

M/c specification:

The Vertical Strength Fabric Tester (Pendulum Lever)
Good brand & Co. Ltd., Capacity: 0-2000lbs

Apparatus:

Cotton fabric
Fabric strength tester
Scissors

Sample:

Size – 8 inch X 2 inch.
No. of sample – 20 (For warp way-10, for weft way-10).

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 %

Working procedure:

At first 12inch × 2inch fabric was cut out from a big piece of fabric. The excess amount of fabric was cut because the two jaws will require at least 2inch each to grip the fabric. Thus 10 samples were cut down for testing.
Now, the first sample is fixed with the upper jaw J₁and the lower jaw J₂.
The m/c is started and observed the dial until the sample is torn out.
When the sample is torn out the m/c is stopped and the reading is taken.
By this way the others’ reading are taken.
At last average and CV% are calculated.

Data:

Warp way:

Reading	Fabric strength (lbs)	Avg. strength (lbs)	SD	CV %
1	80
2	87
3	86
4	78
5	80	82.3	3.23	3.92
6	85
7	84
8	80
9	79
10	84

Weft way:

Reading	Fabric strength (lbs)	Avg. strength (lbs)	SD	CV %
1	71
2	64
3	69
4	72
5	74	70.4	2.9	4.24
6	70
7	68
8	74
9	70
10	72

Result:

The warp way fabric strength = 3 lbs
The weft way fabric strength = 4 lbs
The CV% for warp way fabric strength = 92%
The CV% for weft way fabric strength = 24%

Remark:

The strength of a fabric varies with (1) EPI variation, (2) PPI variation, (3) Count variation. The strength of the fabric also varies if the length and width of the fabric to be tested is changed. If we take a sample which size is 3inch×6inch and another sample size 2inch×6inch then the strength of the first sample will be greater than the second one. Thus if we increase the length of the second sample then the strength of the second sample will be decreased. The strength of the fabric also depends on the construction of the fabric. A plain fabric is stronger than a twill fabric if made from yarn of same count. The CV% for warp =3.92% &for weft =4.24%. it means there is a lot of variation in strength of the fabric.

Precaution:

Handle the instruments very carefully so that they don’t fall on the floor or on someone’s foot Otherwise it may hart some one.
The sample should be taken from the same package otherwise result will vary for package to package.
In the time of dial reading the middle most line should be taken to consideration.

Conclusion:

I would like to thank our respected teacher for the important instructions. I am also grateful to our lab assistants for their kind help. This experiment helps me to know about fabric strength which is very important for fabric testing. I think this will be very helpful in my future life.

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