Spin-draw winding

Winders are used at the end of the spinning process, LSS or HSS, or at the end of an integrated process (spin-draw winding see Section 17.4.9), always at high speed. Winders for separate drawing processes (see Section 17.4.9) usually operate at <1000 m min f At these low speeds it is possible to wind and twist the yarn simultaneously. This is done for textile yarns. For industrial yarns twist is often applied as a separate aftertreatment. 

Traditionally, spinning and drawing were two separate processes. A spinning spool was made and then unwound again to feed a drawing machine. Later, the two steps were combined. This technique is called spin-draw winding (SDW). 

A few examples for a polyester spin-draw winding process will show this, and hopefully give an impression of how melt-spinning machines are designed. 

Spin-draw winding (SDW) is the standard process for the polyamides spinning speeds are 500-1000 m min , winding speeds 3000-5000 m min . Drawing... 

In parallels, efforts have been made to eliminate intermediate steps for technical yarns for BCF PP filaments, too as a result, spin-draw-winding and spin-draw-texturing processes are used for PP filament production. 

Another effect of the variation of the extensional viscosity is the maximum extend-ibility. For polymers like high-density polyethylene, the rapid increase of the extensional viscosity during the spinning process limits the obtainable spin-draw ratio that is the ratio between the winding velocity and the velocity in the orifice. Examples can be found in an article of Han and Lamonte (1972). 

The hot filaments are cooled by blowing air through the filament bundle and are combined together into a tow band, which is deposited into a can. The fibre thickness is determined by the wind-up speed of the denier setter . Spin draw finish is applied as an aid to subsequent processing. 

The drawing of the filament yarns can be integrated between spinning and winding. Figure 2.52 depicts the various drawing principles. 

Uncrimped yarns used in textiles are mainly spun in the spin-draw process. A low or partially oriented filament yarn is being drawn completely directly after spinning in the same process between two godets. Winding speeds exceed 5000 m/min. 

Stress-induced crystallisation is accomplished by spinning processes, followed by drawing of the spun elements, just by drawing of the spun filaments or by spinning with high-speed winding,... 

---