Lea Strength Tester | Determination of Cotton Yarn Strength and C.S.P.by Lea Strength Tester

Name of the Experiment: Determination of cotton yarn strength and C.S.P. by lea strength tester.

Theory:

Figure: The pendulum lever principle

C.S.P is the product of English count and strength of yarn in pound.

i.e. C.S.P = Strength of yarn in pound x Count in English system.
Again, english count is the no. of hanks in 840 yards length per 1 pound weight of yarn.
i.e. Count =( L*w)/(l*W)
Here, L = length of the sample & l = unit length of the system
W = wt. Of the sample & w = unit wt. of the system.
A lea strength tester measures the strength of one lea
yarn. One lea means 120 yards. Strength is a measure
of the steady force necessary to break a material and
is measured in pound. The m/c works in constant rate of
extension. Assuming the specimen to be extensible and an

absence of any dynamic effects, we get from the figure:
Fr = Mgr = MgRsinq  

As the value of MgR and r are constant, therefore
According to the applied force the m/c dial gives us the
strength in lb on the basis of this q.

Apparatus:
1.Cotton yarn
2.Wrap reel
3.Lea strength tester
4.Electrical balance

M/c specification:

1. The Lea Strength Tester
2. Goodbrand & Co. Ltd.
3. Capacity: 100lb

Testing atmosphere:
Temperature – 29oC and relative humidity – 76%
Standard atmosphere: temperature – 20oC and relative humidity - 65%.

Sample:
Size - One lea cotton yarn (1 lea =120 yards).
No. of sample – 20.

Working procedure:
1.At first one lea cotton yarn is measured by wrap reel and in this way 20 samples are taken for testing.
2.Now, the first sample is fixed with the upper jaw J1 and the lower jaw J2.
3.The m/c is started and observed the dial until the sample is torn out.
4.When the sample is torn out the m/c is stopped and the reading is taken.
5.By this way the others’ reading are taken.
6.Then all the samples are weighted and counts are calculated.
7.C.S.P of the all samples are calculated.
8.At last average and CV% are calculated.

Data:

Reading	Yarn length (yds)	Yarn strength (lbs)	Sample Wt (gms)	Yarn Count (Ne)	C.S.P of the given sample	Avg C.S.P	SD%	CV%
1	120	86	2.6	24.9	2141.39	2397.16	99.9	4.16
2	120	93	2.63	24.64	2291.52
3	120	97.5	2.7	24	2340
4	120	95	2.62	24.73	2349.34
5	120	98.99	2.60	24.92	2466.83

Calculation:
Suppose for first sample, we find length = 120 yards and weight = 2.315gm.
Now we know, 1 lb = 453.6 gm.
Then Count = 24.9 » 25 Ne
And C.S.P = 24.9 X 86 = 2141.39
In this way others are calculated.
Here CV% = 4.16%

Result:
The strength of cotton yarn is 97 lb
and C.S.P is 2397.16
and the C.V% for C.S.P is 4.16%

Remark:
It is considered that fibres having C.S.P less than 1800 are bad or weak, between 1800-2200 are average and greater than 2200 are strong. From our experiment we see that our samples’ average C.S.P is 2397.16 which is greater than the std 2200 and CV% is 4.16. This is proved that there are many variations in this range but our supplied yarn has good strength. So finally we can say that these yarns have good strength fibres. But it may be vary because our testing atmosphere is not standard.

Determination of GSM (Gram per Square Meter) of Woven and KnittedFabrics

Name of the Experiment: Determination of GSM of woven and knitted fabrics.

Introduction:
The GSM of fabric is one kind of specification of fabric which is very important for a textile engineer for understanding and production of fabric. ‘GSM’ means ‘Gram per square meter’ that is the weight of fabric in gram per one square meter. By this we can compare the fabrics in unit area which is heavier and which is lighter. 

GSM Cutter

Objectives:

1. To determine the GSM of the given samples of fabric.
2. To compare the GSM of them.

Theory:
The weight of a fabric can be expressed in two ways, either as the ‘weight per unit area’ or the ‘weight per unit length’; the former is self explanatory but the latter requires a little explanation because the weight of a unit length of fabric will obviously be affected by its width. In woven fabric, the weight per unit length is usually referred to as the ‘weight per running yard’. It is necessary therefore to know the agreed standard width upon which the weight per running yard is based. Usually this width depends upon the width of loom. Before coming the term ‘GSM’ there was another term called ‘lb/100 yards’. This expression is used by British Standard. For measuring this there are a template and a quadrant balance. The template area is 1/100 square yards of which each arm is 1/10 yards in length. For measuring GSM, a GSM cutter is used to cut the fabric and weight is taken in balance. Both of these measurement and method is equally used for both woven and knitted fabrics.

Apparatus:

1. Template
2. Quadrant balance
3. Scissor
4. GSM cutter
5. Electric balance.

Sample:

1. Finished cotton woven fabric
2. Finished cotton knitted fabric.

Atmosphere:
Temperature – 25oC and relative humidity – 67%
Standard atmosphere: temperature – 20oC and relative humidity - 65%.

M/c specification:
Name: Quadrant balance
Brand: Good brand & Co. Ltd.
Scale: 100 yards for fabric.

Working Procedure:

1. For measuring with Quadrant balance, at first we should cut the fabric sample according to the template area. By this way we cut 10 woven samples and 10 knitted samples.
2. Now weigh these samples in pounds by quadrant balance according to 100 yards scale.
3. By this way we get the weight in pound per 100 square yards fabric.
4. For Measuring GSM, we should cut the fabric sample by GSM cutter. By this way cut 10 woven samples and 10 knitted samples.
5. Now weigh these samples by electric balance in grams.
6. By this way we get the weight in gram per one square meter fabric.
7. Now find out the average of these found weights.
8. For woven fabrics find out the weight per running yards assuming the loom width 48 inches.

Data: 

Type	Woven Fabric			Knitted fabric
Sl No.	lb/100 yd2	gm/meter2		lb/100 yd2	gm/meter2
1	20	107.64		38	144
2	19	107.64		37	144
3	19	104.75		35	149.67
4	19	102.86		38	143.81
5	18	102.86		36	148
Average	19.2	106.83		36.8	145.37

Calculation:
For measuring the weight of woven fabric in weight per running yards, form data table we get the weight of 100 yd2 fabric is 19.2 lbs. Now assume the width of loom is 48 inches. Therefore the area of the fabric will be 1.33 yd2. So,

Weight of 100 yd2 woven fabric = 19.2 lbs. 

Weight of 1.33 yd2 woven fabric =  0.255 lbs.

That is weight of fabric per running yard is 0.255lbs or 116 gms.

Result:

1. The weight of woven fabric is 19.2 lbs/100 yd2 or 106.83 GSM.
2. The weight of knitted fabric is 36.8 lbs/100 yd2 or 145.37 GSM.
3. The weight of woven fabric per running yard is 0.255lbs or 116 gms.

Remark:
This is a direct measuring tester. So the result should be accurate. But as the samples are of both cotton fabrics, so there are effects of moisture content on the weight of fabrics. Besides the knitted fabrics are very much extensible and proper relaxed state is quite different during cutting of sample with GSM cutter. Therefore there are variations among their weights. The effects of moisture content can be accounted for either by conditioning the specimen in the standard atmosphere or by taking the specimen to oven dry weight and adding the official regain. 

Fabric Stiffness Testing | Determination of Fabric Stiffness by ShirleyStiffness Tester

Name of the Experiment: Determination of fabric stiffness by Shirley Stiffness Tester.

Introduction:
Stiffness is a special property of fabric. It is the tendency of fabric to keep standing without any support. It is a key factor in the study of handle and drape of fabric.

Shirley Stiffness Tester

Objectives:
To measure the stiffness of the given fabric sample.

Theory:
A rectangular strip of fabric, 6 in. x 1 in., is mounted on a horizontal platform in such a way that it over change, like a cantilever, and bends downwards as shown in figure.

Three specimens in warp way and three in weft are usually tested and since he relative humidity can affect the results the test should be made in a standard testing atmosphere. The horizontal platform of the instrument is supported by two side pieces made of plastic. Attached to the instrument is a mirror which enables the operator to view both index lines from a convenient position. The scale of the instrument is graduated in centimeters of bending length and it also serves as the template for cutting the specimens to size.

Apparatus:
1. Stiffness Tester
2. Scissor
3. Scale

Sample:
Cotton woven fabric
Size: 6 X 1².

Atmosphere:
Temperature – 25oC and relative humidity – 67%
Standard atmosphere: temperature – 20oC and relative humidity - 65%.

M/c specification:
Name: Shirley Stiffness Tester

Procedure:
1. To carry out a test the specimen is cut to size 6 in. x 1 in. with the aid of the template.
2. Both the template and specimen are transferred to the platform with the fabric underneath.
3. Now both are slowly pushed forward.
4. The strip of the fabric will commence to droop over the edge of the platform and the movement of the template and the fabric is continued until the tip of the specimen viewed in the mirror cuts both index lines.
5. The bending length can immediately be read off from the scale mark opposite a zero line engraved on the side of the platform.
6. Each specimen is tested four times, at each end and again with the strip turned over.
7. In this way three samples are tested.
8. Finally mean values for the bending length in warp and weft directions can be calculated.

Data:

S/n		Warp (CMS)			Weft (CMS)
		Right	Left	Mean	Right	Left	Mean
1	F	2.1	2.15	2.66	2	2.39	2.51
	B	2.25	2.25		2.68	2.75
2	F	3.1	3.15		2.4	2.2
	B	2.89	2.97		2.75	2.9
3	F	2.5	2.89		2.2	2.25
	B	2.75	2.95		2.71	2.85

Table: Bending length obtained from test

Result:
The bending length of the fabric in warp way is 2.66 cms.
The bending length of the fabric in weft way is is 2.51 cms.

Remark:
If the bending length of the fabric is more than fabric stiffness is more and if less stiffness is less. From the experiment we see that the bending length of the given fabric is average both in warp and weft way. So the stiffness of the sample fabric is average.