َArticles are OPEN Access and publication is free of charge

Document Type : Original Article


1 Department of Textile Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.

2 Department of Textile Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.


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.