Providing a New Method for Evaluating the Nip Stability in Intermingled Yarn

The aim of this study is to provide a method to evaluate the intermingled nip stability. for this purpose, polypropylene (fully drawn yarn) fdy with three types of intermingling heberlein jet inserts (p412, p212, and s16) and three air pressure values of 2, 3, and 4 bar was subjected to the texturing process. in measuring the nip stability in the previous methods, i.e. using the nip number, it was observed that in some long nips with special structures, a nip with certain length under the stretching process may become several nips with a less total entanglement length. this can cause an error in evaluating the nip stability. therefore, in order to evaluate the nip stability, it is suggested to use the nip length in the 360° study around the yarn axis to evaluate the effect of the change in the length of the intermingled areas due to stretching. using the method presented in this research and after performing experiments, the maximum and minimum nip stability with considering the nip length were 97.3% (for p412 jet insert and 4 bar air pressure) and 48.55% (for s16 jet insert and 2 bar air pressure), respectively. however, the nip stability in the same test conditions based on nip density was 74.47 and 52.94%, respectively.