Studies on melt spinning. IV. On the stability of melt spinning

Abstract

The stability of melt spinning has been studied theoretically by solving for transients the perturbed form of the simultaneous partial differential equations of melt spinning introduced by the author in a previous study. Computed stability limits summarized in the form of maps in the (t*—St) plane with the cooling air speed serving as the third parameter showed that the thread must be in a molten state at the take-up before an instability can develop and that the cooling of the thread by air plays a predominant role in stabilizing the melt spinning. Here, t* is air temperature and St is the Stanton number. Draw resonances were observed experimentally in a water-quenched melt spinning of PET fiber and in the casting of PP film. Experimental results agreed well with theoretical simulations with respect to oscillation periods and stability. Draw resonance observed by Bergonzoni et al. was closely simulated by means of the present theories.