ABSTRACT
The subject of instability in fiber spinning and film blowing encompasses the entire gamut of instabilities leading to the process stoppage or unstable operations with deviations from desirable steady conditions. A host of factors ranging from various process disturbances to fundamental instabilities like draw resonance can possibly cause such stoppage or unstable operations. The category of process disturbances can cover those of input materials or of dynamic conditions, or even of geometric dimensions of the process equipment. The disturbances originating from the input materials are usually related to some sort of inhomogeneities in the input material characteristics such as inhomogeneous densities, molecular weights, etc. The group of process disturbances in dynamic conditions can include those in state variables such as process velocity, temperature, stress, etc. The final group of disturbances could be associated with imprecise geometric dimensions of the replaced parts of the equipment.
