IPI - Imperfection
Thin places, thick places and neps are known as imperfections, or so-called "IPIs". Since the electronic measurement of yarns, these undesired events are defined as mass increase of +50% for thick places, -50% for thin places, +200% for ring-spun yarn neps and +280% for rotor yarn neps. Over the decades the evenness of yarns improved considerably, so that nowadays, often more sensitive settings are applied to describe the imperfections occurring in a yarn. Also the spinning system (ring, OE, airjet, compact), the process (carded, combed), the yarn count and the material play a determining role for the occurrence of imperfections.
The imperfections are based on the mass signal of the capacitive sensor of YARNMAP. The imperfections of all levels are counted and given as events per 1000m in the report. The results are highly reproducible and can be compared to other yarn testing instruments with the same measuring principle.