Continuous filament polyester can be supplied in many forms, but the most common for industrial use are partially oriented yarn (POY) and highly oriented yarn (FOY).

What is Partially Oriented Thread (POY)?

The yarn facing section is made by melting and extruding a polyester chip or flake (melt cycle). During spinning, the filaments are stretched or drawn five times their original size to target the polymer to meet the desired uniformity, strength, shrinkage, and elongation. Thus, the term "slightly biased thread" refers to more threads that stretch slightly. POY generally has lower strength and is less uniform than fully oriented yarn (FOY). POY is primarily used in texturing to create decorative yarns and can also be used in drawing to form knit and warp knit fabrics.

What is Fully Oriented Thread (FOY)?

FOY Polyester (also called Fully Drawn Yarn - FDY) is produced using the same process as POY, except that the yarn is produced at high speed due to the central draw included in its process. This allows stability with concentration and crystallization. FOY is mainly used in fabric production as a weft or warp. FDY can be knitted or crocheted with any other filament yarn to produce different types of fabrics. FOY polyester yarn is used for industrial applications that require uniform and consistent strength, elongation and shrinkage. Most fasteners, industrial sewing thread and hose fasteners are made from FOY polyester.

There are many different types of industrial polyester yarn with different physical properties controlled by the polymer formula and the condition of the POY or FOY yarn. Choosing the right yarn type can be difficult, so working with a trusted partner to match the right polyester yarn to your application is key to rapid optimization and product improvement.