A brief discussion on polyester sewing thread

- Jan 11, 2018 -

The ancient ancestors developed the sewing thread of various types with the technique of sewing needle thread.

In the production of clothing, a line and its continuous improvement of the process has created a number of brands.

It goes without saying that line plays an important role in clothing.


1. Classification of sewing thread.

Sewing thread is made of pure cotton, nylon, polyester cotton, blended yarn, polyester and rayon, etc., generally consists of two, three, four, six shares single yarn twist together and become, twisting direction can be divided into S twist and Z twist two kinds.

The flat sewing machine generally adopts the Z twist suture, and the quality S twist line can be applied on other sewing machines.

Cotton sewing thread sewing performance is good, but when the washing shrinkage than synthetic fiber line, its strength, chemical resistance and abrasion resistance than synthetic fiber is poor, high quality mercerized cotton is expensive, therefore, is now rarely used cotton sewing thread.

Short fiber polyester sewing thread cost is low, suture stability, durability and sewing are good, so it is suitable for all the conventional garment sewing.

The sewing thread used in the sewing machine is usually cotton thread, but because of the high cost of cotton fiber at present, it is usually replaced with polyester thread.

Here are the characteristics of various lines:

(1) high strength polyester thread: currently it is one of the most conventional and widely used sewing thread varieties in the market, characterized by good luster, inelasticity, good color fastness and strong tensile strength.

It is widely used in PVC, thick cloth, nylon leather goods sewing.

(2) fishing net line (transparent line) : the transparent line has nylon and polyester monofilament, which is also different in scale, hardness, tension and use.

It is often used for weaving, sewing, tailoring, seaming and various kinds of craft products.

(3) pure cotton yarn (polyester staple fiber) : polyester staple line is a conventional line widely used and widely used. It has a little hair on the surface, and its strength, luster and wear resistance are inferior to other lines.

It is used in thin fabrics, pure cotton thread is made of natural cotton combed and the stock is singed, it is specially for pure cotton cloth sewing and production.

(4) wax rope line (up) : nylon, polyester, wax rope line cent two kinds of material, linear flat is preferred, pull strong, after wax wax rope line, often used in thick leather sofa, outdoor gear, casual shoes, leather and other products sewing thick or hand sewing operation.

The relationship between sewing thread and sewing needle.

(1) select the thickness of the suture.

The use of fine sewing thread should be considered first when choosing the thickness of suture.

Specific from the following aspects: the volume of the sewing machine is limited, and the sewing thread can be used for longer sewing thread, which can save the time of the shuttle.

The small sewing thread is small, and the chain stitch is good.

There is little space for sewing thread, which causes less distortion and wrinkles.

A small number needle can be used to avoid needle holes in the fabric.

The fine sewing thread can also reduce the protrusion of the seam and reduce the impact of wear on the inner surface of the fabric.

In the process of sewing, to form the correct line trace, it is necessary to ensure the matching of stitches, stitches and seams.

In addition, there are two points to note:

One is to consider the twist of the thread in the sewing process. The purpose of the stitching is to increase the strength and elasticity, but if the twist is too large, the thread ring will be affected by the twist.

In general, the two ends of the thread should be taken to the two ends of the line, so that the natural torsion winding number of the two strands should not be greater than 6, otherwise, it is easy to cause the jump needle failure.

Second, such as sewing the material when sewing thin soft must with fine needle, should increase the amount of rebound of needle at the same time, because the stitching and sewing the material of the friction force is small, such as in distance is the same, relatively reduce surface lines ring width, affect the normal hook, jump needle fault.

If it's rough, it's the opposite.

(2) selection of machine needle.

In the case of suture, the needle is also important to be considered in sewing.

The working nature of the machine determines the selection of the machine needle. Different types of machines should be equipped with different types of machine needles, such as the flat sewing machine with 96 '1 or 88' type 1 needle;

The sewing machine USES 18 '1 machine needle and so on.

No matter which type of machine, the sewing process should be based on the quality of the seam and the size of the needle.

Generally speaking, needle for textiles and knitwear, its tip are ground into a cone, sewing leather and sewing the material is similar to that of the use of special shape pins, such as the spear, ling pointed, twisting, pointed and so on, purpose is to increase the intensity of needle, obtain good sewing effect.

Iii. Calculation and cost of line consumption.

In most of the garment factory is such a problem: all kinds of sewing thread stack up, however, whether it's newly developed or warehouse inventory, it virtually in the waste of cost, in order to avoid excessive waste of production line, introduce the line amount calculation method and meaning: one is to the needs of the garment cost accounting: thread is part of the total cost of the garment production, only for it has a more accurate calculation, to make full cost accounting products.

Second, it is conducive to planning and management: knowing the line quantity, facilitating procurement and preparation, and providing the necessary conditions for the timely delivery and quality assurance of garments.

There are two kinds of calculation lines: "ratio method" and "formula calculation method".

(1) use the ratio method to estimate the line quantity.

The dosage of the sewing thread is determined by many factors, such as the thickness of the fabric, the fabric of the kinds of hard and soft, stitch, stitch lines to the density, thickness, the size of the tension and the machine presser foot pressure, etc.

These factors often change, so it is not easy to calculate the number of lines accurately.

At present, the normal use ratio method is used to estimate the line quantity.

So-called "ratio method", is based on the experiments under various conditions are summarized and stitch lengths of cloth, the consumption of sewing thread length (m) and sewing cloth length (m) the ratio of the E = L/C, this is called E thread consumption ratio, with the ratio of E, can use it to estimate the practical dose.

In L=C·E, L is the line quantity (m);

C for sewing length (m), E for suture consumption ratio.

Using the ratio method to estimate the line quantity, the ratio E is calculated first by experiment.

There are two methods for the specific experiment, namely the stitch length method and the stitch length method.

It's a long way to sew.

First of all, doing well the preparation work of experiment, the sewing machine, choose the good performance of adjust each place according to the actual requirements of the process conditions, and ready to fabrics and sewing thread, and then measuring lengths of thread (e.g., 1 m), the amount, he would leave a 0.5 m headroom front end.

Measuring the line with obvious color marking, again to spool cover according to the actual operation requirements in this paragraph after sewing thread on the selection of fabric for actual stitching, until finish all marked with color line seam.

Finally, the fabric is taken out of the car, and the length of the actual sewing of the color line segment is measured, so as to calculate the line amount of each meter seam, that is, the ratio E is obtained.

E= the length (m) of the length (m) of the color line segment (m).

A stitch length method.

The preparation work of the experiment is the same as the above method, and then the sewing thread and fabric are applied directly to the driving seam, and the car is sewn to more than 0.5m.

The middle portion of the online trace after the sewing has a certain length (over 20cm), and cut off the track with the scissors.

Finally, the sewing thread in this line is removed (careful not to break the line), and the actual length of the measuring line can be calculated to calculate the line amount of each meter line, that is, the ratio of E.

E= the length (m) of the actual length (m)/ line trace of the disassembly line.

If the same sewing thread is used, only the on-line amount can be tested, and the total line amount is twice as much as the on-line amount.

Because of the different structure of the upper and lower wires, the other lines should be carried out separately to obtain the consumption ratio of the line and the lower line.

For example, with flat stitching, the line density is 8 stitches /2cm, the fabric thickness is 1mm, the sewing thread is 9.8 Tex x 3(60 English branch /3), the length of the sewing length is 6.5m, and the thread count of the garment is estimated.

As can be seen from the garment technology book, E=2.73, so L=E·C=2.73 x 6.5=17.745m.

(2) use the formula calculation method to calculate the line quantity.

This method is based on the shape characteristics of various lines, and calculates the line quantity of a unit stitch, and then calculates the formula of the actual line quantity of the fabric with a certain length.

Formula of calculation can be divided into three steps: first, according to the characters of the shape of the stitch, stitch geometry idealized, hypothesis for the rules of geometry, for example, each flat stitch sewing circle can assume as a rectangle or oval.

2. Calculate the line amount of the unit line trace according to the assumed geometry.

The lines of each unit line include the amount of wire used for each coil and the amount of each coil connected to the adjacent coil.

According to the formula of the line of the unit line and the line trace density, the formula for calculating the line quantity for the calculation of a meter long line is calculated.

In the case of flat suture (301), it can be obtained: L1=2+ 0.2dt + 0.26d /(Nm*)1/2;

L2 = 1.57 + 0.16 + 0.36 D/Dt (Nm * delta) 1/2

In the above equation, the calculation formula of sewing thread length (m) is required for the stitch length of the one meter long fabric when the L1 - flat stitch is assumed to be a rectangle.

L2-ping stitch is assumed to be an ellipse, and the length of sewing thread length (m) is calculated for the sewing thread length (m).

D - trace density (line change unit /2cm).

T - thickness of fabric (mm).

Nm - the metric count of sewing thread.

As for the proportion of sewing thread, the pure cotton line is about 0.8 ~ 0.9g/cm3, and the tc is about 0.85 ~ 0.95g/cm3.

For example, it is known to use flat stitching stitching, line trace density D=9, fabric thickness t=1.2mm, sewing thread is 60/3 polyester thread, the total length of the sewing thread is 6.5m, and the amount of thread used is calculated.

Calculation: the line shape is assumed to be a rectangle, and Nm=1.693Ne=1.693603 =33.86.

L1 = 2 * 9 * 1.2 + 0.26 + 0.2 * 9 1/2 = 4.58 m/(33.86 * 0.9), have to stitch length = L1 * 6.5 = 4.58 * 6.5 = 29.77 m.

Line mark shape assumption for the oval, the L2 = 1.57 + 0.16 + 0.36 D/Dt (Nm * delta) 1/2 = 1.57 + 0.16 * 9 * 1.2 + 0.16 * 9 1/2 = 3.88 m/(33.86 * 0.9), have to stitch length = L2 * 66.5 = 25.22 m.

In fact, an ordinary domestic line about 3 yuan, and entrance line reached 20 yuan a, is domestic line of dozens of times, but no matter such as colour fastness and shrinkage are superior to domestic line.

The clothes that retail price thousands of yuan should accomplish everywhere perfect, pay attention to more is quality, do not calculate the price of line, ability won't because of "cause small lose big".

In garment process, the choice of suture needle, thread look is a very simple question, but it is not, it is not only to meet the requirements of technology, also care for aesthetic, from suture needle, thread and sewing the material match, stitching and sewing the material color is tie-in, suture fineness choose various consideration, in order to achieve a more perfect effect.

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