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

The aim of this study is to provide a method toevaluate the intermingled nip stability. For this purpose,polypropylene (fully drawn yarn) FDY with three types ofintermingling Heberlein jet inserts (P412, P212, and S16) andthree air pressure values of 2, 3, and 4 bar was subjected tothe texturing process. In measuring the nip stability in theprevious methods, i.e. using the nip number, it was observedthat in some long nips with special structures, a nip withcertain length under the stretching process may becomeseveral nips with a less total entanglement length. This cancause an error in evaluating the nip stability. Therefore, inorder to evaluate the nip stability, it is suggested to use the niplength in the 360° study around the yarn axis to evaluate theeffect of the change in the length of the intermingled areas dueto stretching. Using the method presented in this research andafter performing experiments, the maximum and minimumnip stability with considering the nip length were 97.3% (forP412 jet insert and 4 bar air pressure) and 48.55% (for S16 jetinsert and 2 bar air pressure), respectively. However, the nipstability in the same test conditions based on nip density was74.47 and 52.94%, respectively.