Major Warping Defects- On Sectional warping

Snarlings and Overlappings

These are caused by irregular yarn tension. The broken end is not tied-up by the operative with the yarn end on the drum.

Different lenghts of sections, High Wastage Rate

This is caused by over-or-under warping of sections, untimely laying of lease cords due to faulty operation of the counter and the carelessness of operative.

Overlapping/Excessive Distance

The sections overlap each other or there is an excessive distance between them. This is caused by support improperly set and the careless of warper operative.

Stripiness in the Warp

This is caused  by improper mixing of raw material

Irregular Winding

Irregular winding on the warper's beam which is displaced towards one end. This is due to improper position of the weaver's beam in warp beaming.

Different lenghts of Ends

It also includes irregular distribution of the section in the weaver's beam width. This is caused by improper fixing of section ends to the weaver's beam.

Excessive or insufficient number of yarn ends in the warp

This is caused by improper calculation at gaiting.

Warp Beaming on a defective weaver's beam

This is caused by carelessness of the assistant foreman and the warper operative.

Incorrect Laying of lease cords, or their absence in some sections

Again this is caused by carelessness of the warper operative.      

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Suitability of a fiber for a blend

Fibers in a blend are chosen keeping in mind various properties of the constituent fibers. Thus a blend is chosen which gives the best of properties of the different constituents of the blend. The properties that are considered can be strength, absorbency,crease resistance, resistance to abrasion, resistance to heat, bulkiness,resistance to pilling and Dimensional stability.All the fibers do not have all the properties that are desired. This is the very reason why blend is chosen.

Cotton has moderate strength and dimensional stability. However, it is excellent in absorbency, resistance to heat and pilling. It has an average resistance to abrasion and poor bulkiness properties and crease retention.Thus it is added in the blend to have excellent absorbency properties.

Viscose Rayon has excellent absorbency, resistance to heat and pilling. Thus it is similar to cotton in these properties.It has however, poor resistance to abrasion, bulkiness, crease retention and stability. It has an average strength. It has absorbency properties similar to cotton. It is also cheaper than cotton.

Acetate Rayon has excellent resistance to pilling and stability. It has moderate resistance to heat and average absorbency, crease retention and stability. However its resistance to abrasion is very poor.

Wool has excellent absorbency, bulk and wrinkle resistance. However, it has poor stability. It has moderate abrasion and heat resistance. Its crease retention, resistance to pilling and strength can only be considered as average.

Nylon has excellent strength, stability and abrasion resistance. However, It has poor absorbency and bulk. It has moderate crease retention and average resistance to heat and pilling.

Polyester has excellent strength, stability, crease retention and abrasion resistance. However it has poor absorbency, bulkiness properties and resistance to pilling. Its resistance to heat is average.

Acrylic has excellent bulk and stability. It has moderate resistance to heat and average crease retention and strength. Its resistance to abrasion and pilling and absorbency are very poor.It is similar to wool in most of the properties. It is also cheaper than wool.

Modacrylic has excellent stability and bulk properties. However its absorbency, resistance to heat and pilling is very poor. It has average strength, resistance to abrasion and crease retention.

Polypropylene and Polyethylene have excellent stability and strength. They have poor absorbency, bulk and heat resistance. The have average crease resistance and resistance to pilling.

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Seam Strength Vs. Seam Slippage

Difference Between Seam Strength and Seam Slippage

Both the parameters measure the performance of seam. Seam strength referes to the strength when seam finally ruptures or when the fabric breaks.

However before rupturing there is an unacceptable opening in the seam which makes the seam 'failed' commercially even when there is no visible rupture. Seam slippage measures that.

Seam strength depends upon stitch type, thread strength, stitches per inch, thread tension, seam type and seam efficiency of the material.

Seam slippage depends upon the stitch rate, the weave structure of the fabric and the width of the seam allowance.  

There is another term called 'yarn slippage' which measures the shifting of warp yarn over weft yarn to render the garment unusuable. 

Yarn slippage depends upon a low number of warp or filling yarn, two shallow seam allowance, too tight a fit and improper seam construction.  

Find Pictures of Seam Quality Defects here.

Fabric Parameters

Woven fabric parameters

There are four basic parameters that are essential for every woven fabric.

1. Ends per Inch and Picks per inch (EPI and PPI).
2. Yarn count
3. Crimp

4. Weave or Fabric Structure or Design

1. Ends per Inch or Picks per Inch

It is a measure of thread density. The normal method used to determine thread density is to use a pick glass.

2. Yarn count

EPI and PPI affects the compactness of the fabric. It is also known as thread count or cloth count. Thread counts range from as low as 20 threads per inch as used in tobacco cloth to as high as 350 threads per inch, found in type writer ribbon fabrics. Normally EPI and PPI of a fabric are described as EPI×PPI. Thus a fabric of 74×66 means 74 EPI×66 PPI.

Balanced constriction

A fabric is said to be well balanced if the number of warp yarns and weft yarns per inch are almost equal.

3.Crimp

Crimp refers to the amount of bending that is done by thread as it interlaces with the threads that are lying in the opposite direction of the fabric. Crimp is defined as the ratio of difference of length of yarn (Ly) taken from length of fabric (Lf) to the length of fabric (Lf).

Crimp = (Ly-Lf)/Lf

Often it is more convenient and preferable to use percentage values. Thus we can define crimp percentage as:

Crimp% = (Ly-Lf)/Lf

A crimp will normally give values ranging from 0.01 to 0.14 ie. (1% to 14%).

Crimp is related to many aspects of the fabric. It affects the cover, thickness, softness and hand of the fabric. When it is not balanced it also affects the wear behaviour and balance of the fabric, because the exposed portions tend to wear at a more rapid rate than the fabric. The crimp balance is affected by the tensions in the fabric during and after weaving. If the weft is kept at low tension while the tension in warp directions is high, then there will be considerable crimp in the weft and very little in the warp.

4. Weave

It refers to the arrangement of warp and weft in the fabric.

OTHER FABRIC PROPERTIES

1. Fabric weight (W)

It is the weight of the yarn per square meter in the woven fabric, which is the sum of the weight of the warp (W1) and weight of the weft (W2).

Weight of the warp is calculated as (per square m):

W1= [n1 x 100 (1+c1%)/100] x [N1/1000] g

Where
n1 = Ends per cm
N1 = Warp count in Tex

C1% = Warp crimp percentage.

Similarly weight of the weft is calculated as (per square m)

W2= [n2 x 100 (1+c2%)/100] x [N2/1000] g

Total weight per square meter = W1+W2

weight/piece = (W1+W2) × piece length × piece width in gram.

Example

A fabric 120m long, 1.3 m wide and having 30 ends per cm of 12 tex warp and 24 picks per cm of 15 tex weft. The warp and weft crimp percentages are five percent and eight percent respectively. We describe these fabric particulars as
30×24; 12 tex × 15 tex; 5%×8%

Warp weight per square m = [30 x 100 x (1+5)/100] x [12/1000] = 37.8 gms

Weft weight/square m = [24 x 100 x (1+8)/100] x [15/1000] = 38.8 gms

Piece weight

= total weight per m × piece length × piece width
= 76.68 × 120× 1.3
= 11962.08 gm or 11.96 kg.

2. Cover factor

(K) it is defined as the area covered by the yarn when compared with the total area covered by the fabric.
The warp cover factor can be found by using the formula.
k1= n1 x sqrt(N1)/10
Where
n1 = Ends/cm
N1 = Count of warp in tex

Similarly the weft cover factor can be found by the formula

k2 = n2 x sqrt(N2) /10

So the total cover factor is
K = K1 + K2

Thus with fabric (30×24; 12 tex×15 tex) the values are

k1= (30 x sqrt12)/10 = 10.39

k2 = (24 x sqrt15)/10 = 9.30

K = K1+K2 = 10.39+9.30 = 19.69

3. Fabric Thickness

For a wide range of fabric, this parameter is not important, but it becomes critical for fabrics that are to be used as belts and felts.

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