The Process Difference on POY Yarn and FDY Yarn

The main process difference between POY (Partially Oriented Yarn) and FDY (Fully Drawn Yarn) lies in the stretching or drawing stage during their production. Here’s a brief overview of the processes for both types of yarn:

 POY (Partially Oriented Yarn) Process:

Melting and Extrusion: The process begins with melting polyester chips, which are made from raw materials like purified terephthalic acid (PTA) and monoethylene glycol (MEG). The molten polyester is then extruded through spinnerets to form continuous filaments.

Cooling and Solidification: The extruded filaments are rapidly cooled by air or water to solidify them into a semi-solid state.

Orientation: The partially solidified filaments are passed through a series of godets or rolls that rotate at different speeds to stretch them slightly. This partial stretching aligns the polymer chains to a certain extent, resulting in partial orientation.

Winding: The partially oriented filaments are wound onto bobbins or packages as POY yarn. It is worth noting that POY is not fully stretched or drawn.

FDY (Fully Drawn Yarn) Process:

Melting and Extrusion: The initial steps of melting the polyester chips and extruding them through spinnerets are similar to the POY process.

Cooling and Solidification: The extruded filaments are rapidly cooled to solidify them into a semi-solid state, just like in the POY process.

Drawing: Unlike POY, the partially solidified filaments in FDY undergo further stretching or drawing. This drawing process involves passing the filaments through a series of heated godets or rolls that rotate at different speeds. The heat softens the filaments, and the rolls stretch them to their maximum potential, aligning the polymer chains and imparting strength and orientation.

Heat Setting: After drawing, the FDY filaments are heat-set to stabilize the molecular orientation achieved during the drawing process.

Winding: The fully drawn filaments are then wound onto bobbins or packages as FDY yarn.

In summary, the key difference between POY and FDY lies in the stretching or drawing stage. POY is only partially stretched, while FDY goes through a complete drawing process, resulting in fully oriented and stronger filaments.