What do POY, DTY, and FDY represent, and can you tell them apart?

What do POY, DTY, and FDY represent, and can you tell them apart?

01

The properties of filament, such as strength, elongation, boil shrinkage rate, and dyeing uniformity, depend on the microscopic structure of the fibers. Among these, factors like orientation and crystallinity in the supramolecular structure play a crucial role. Only through stretching, under the influence of tensile stress and temperature, can the filament achieve the necessary supramolecular structure.

Different spinning speeds and stretching speeds determine the crystallinity and orientation of the synthetic filament, resulting in different types of filaments such as POY, DTY, and FDY.

common types

1、POY（PRE-ORIENTED YARN）

Pre-oriented yarn (POY) refers to partially stretched synthetic filament obtained through high-speed spinning, with a degree of orientation between un-oriented yarn and stretched yarn. Compared to un-stretched yarn, it has a certain level of orientation and good stability. POY generally has two main uses: one is to be directly used for weaving, although this is seldom done; the other is for further processing into draw-textured yarn (DTY).

2、DTY（DRAW TEXTURED YARN）

Stretch deformed yarn or false twist deformed yarn is made from POY as the raw material, processed through stretching and false twisting deformation. It often possesses a certain degree of elasticity and shrinkage.

3、FDY（FULL DRAW YARN）

Fully stretched yarn is a synthetic filament further produced through spinning and stretching. The fibers are fully stretched and can be directly used for weaving and warping processes.

Identification methods

Distinguishing the three types of filaments is relatively simple. First, observe their appearance: DTY fibers are curly. Then, stretch them by hand; FDY has slightly lower strength compared to POY, but during stretching, FDY will elongate a bit less.

other types of chemical fiber

1、Raw yarn

Unstretched yarn (conventional spinning) (UDY), semi-pre-oriented yarn (medium-speed spinning) (MOY), high-oriented yarn (ultra-high-speed spinning) (HOY).

2、Stretched yarn

Low-speed stretched yarn (DY), fully drawn yarn (one-step spinning method) (FOY).

3、Deformed yarn

Conventional deformed yarn (DY).

02

Conventional spinning process: Conventional spinning, also known as low-speed spinning, employs a three-step process involving spinning, winding, stretching, and false twisting deformation (UDY-DY-TY). The spinning speed ranges from 1000 to 1500 m/min, while the stretching and twisting speed is between 600 to 1100 m/min. The false twisting deformation speed is 120 to 160 m/min, and the post-processing stretching multiple is 3.5 to 4.2 times (before false twisting deformation processing). It can produce filaments ranging from 33 to 167 dtex.

Advantages: Mature process, stable equipment operation, easy-to-master technology, good product quality, and uniform dyeing.

Disadvantages: Long process flow and low production efficiency.

Medium-speed spinning process: This uses a two-step process, with a spinning speed of 1800 to 2500 m/min to produce semi-pre-oriented yarn (MOY). There are two production routes: MOY-DY process and MOY-DTY process. The efficiency and quality of filament production in this type of process are not very high.

High-speed spinning process: The spinning speed for high-speed spinning is 3000 to 3600 m/min, which produces pre-oriented yarn (POY). There are three process routes for high-speed spinning: POY-DTY process, POY-TY process, and POY-DY process, with the first one being the most commonly used. It utilizes high-speed spinning and high-speed stretching deformation, representing a typical two-step process. The post-processing speed of POY is usually 400 to 800 m/min, and it can produce deformed yarn (DTY) ranging from 50 to 167 dtex. Its characteristics include a short process flow, high production efficiency, and reduced infrastructure investment. POY can be stored for long periods and transported over long distances, and DTY has excellent quality.

Spinning-stretching one-step process: The filaments produced by this process are fully drawn yarn (FDY). This process combines spinning and stretching in a single spinning-stretching machine, representing a one-step process route. There are two production methods: one has a spinning speed of 900 to 1500 m/min and a stretching speed of 3200 to 4000 m/min, with a stretching ratio of 3.5 times, capable of producing stretched yarn ranging from 55 to 165 dtex; the other has a spinning speed of 2600 to 3500 m/min and a stretching speed of 5100 to 5500 m/min.