Knowledge of woven fabric (part 2)

Also in these articles, I will talk about some requirements for assessing the quality of each fabric. What are the requirements that must be met to become a commodity in some export markets such as the US, Europe … these are the basic parameters of woven fabric

1 / Density or Thread count (Threads per Unit Length)

hinh-5The fabric density is an important parameter. Fabric density is the number of yarn count per unit of fabric length vertically or horizontally. For example, the average density of cotton yarn is 18 fibers / 1 cm or 45 yarn / inche. High-end fabrics usually have fiber density of 22 fibers / 1 cm or 55 fibers / inche or more. High density, combined with the thin fabric will make the fabric more soft, silky. Large density with large size fabric for strong, durable fabric.

+ Density of warp: The number of warp per unit length in the horizontal direction, usually the number of warp threads per inch (End per inche or abbreviated as EPI).

+ Weft density: The number of weft per unit length in the longitudinal direction, usually the number of weft per inche (Pick per inche or abbreviated PPI).

For example: 100% cotton dyed twill woven fabric, 126 × 54, 20Sx10S

The fabric density is 126 weft / inche and 54 weft / inche.

Or: Fabrics with Thread count: 297 × 88. That is, the fabric has EPI = 297 and PPI = 88.

The index in front of it is always vertical density and the latter is horizontal density.

The test method that is commonly applied according to the international standard for this parameter is ASTM D3775-2012.

EPI stands for Ends Per inche and PPI stands for Pick Per Inche. Here the Ends are known as warps and the Pick is called the weft (Fills).

How do you know which yarn is a warp or a warp in a woven pattern?
Usually the EPI warp density is more than the EPI weft density
Bending on yarn strength: Warp yarn strength is usually higher than weft strength.
The warp is usually stronger and the twist is higher than the weft.
If it’s a striped fabric, the warp is usually the direction of the stripe.
If the fabric has a selvedge, the warp is parallel to the selvedge. The weft is perpendicular to the selvedge.
It is relatively more difficult to pull the warp threads from the fabric than the weft.
After the yarn has been removed from the fabric, the warp is usually straighter than the weft.
Detect warp based on sizing on the warp. Weft has no glue.
In the picture above, an example of a fabric pattern is quite sparse. The square drawn is the area with 1inche edge. In the square you can count there are 9 warp and weft. Thus, the EPI and PPI of this fabric pattern are 9 x 8.
2 / Yarn count or Yarn size or Counts of Yarn: Fiber size or roughness of the fabric is the second most important factor after the density of the fabric. The finer the yarn, the softer the fabric is, but the surface of the fabric is weaker than that of the larger yarn. This drawback can be overcome by increasing the density of yarn to increase the strength of the fabric. Fabrics with large fiber sizes, often of medium density, give the fabric a very durable, strong, easy to wash and preserve. However, this fabric can feel a little hard. Silky fabrics will be woven with small yarn size and large fabric density. For example, silk, tencel … often have very thin fibers, so the products of silk and tencel are much softer and smoother than other fabrics. The thickness or diameter of the yarn is one of basic characteristics. However, there is no way to measure the fiber diameter in a meaningful way. There are two systems that determine the yarn count used: Directly and indirectly.
Direct system:
The system directly denotes the number based on a measurement of mass per unit length of yarn
The length in the system is fixed
Finer yarns have a lower index
The main numbers used are:
The larger the number, the more raw yarn.
* Tex – weight in grams per 1000 meters
* Denier – weight in grams per 9000 meters.
* Decitex – weight in grams per 10000 meters
1 tex = 10 decitex
For example: 250D yarn means 9000 meters of fiber will weigh 250 grs

D or denior = G (grams) / L (9000m) or grams weight of 9000m of fiber

The bigger D is, the coarser the yarn is, the smaller D becomes the stronger the yarn.

This unit is often used with filament yarn.

1D fine yarn is a Micro filament.

To be able to weave, the yarn must have a minimum of 10D.
The general formula for a direct system is: N = (W x l) / L

Inside:
N: yarn count
W: weight of fiber sample
L: sample length
l: unit of system length

 

The yarn count refers to the roughness of a yarn and is determined by its mass per unit length. It is usually measured in grams per kilometer of fiber, the unit of measurement for this method is called “Tex”. In other words Tex is the weight in grams of a 1000m fiber.

 

Indirect system:
This is a system that represents the count based on the length of the yarn in a unit of mass of yarn.
Is a system based on a defined mass
Finer yarns have a higher index
The main units used are:
New wool count = number of skeins with a length of 560 yards per 1 pound
Cotton count Nec = number of skeins of 840 yards in length per 1 pound
Chi meter Nm = number of Km length over 1

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