The contamination of cotton with synthetic fibres remains a significant concern for spinning mills and Loepfe’s Prisma system for polypropylene clearing continues to evolve. Prisma P-clearing is now optimised for spinning mills facing fluctuating humidity levels in order to offer better fabric quality while maintaining the cut rate of yarns.

Over the past 12 months, extensive trials have been conducted and data collected and used to upgrade the level of accuracy in polypropylene detection by the company, headquartered in Wetzikon, Switzerland. The data was used for optimisation in signal processing and to offer an additional setting function specifically for spinning mills that must contend with pronounced climatic fluctuations.

Polypropylene contamination, typically stemming from bale packaging, can lead to a myriad of issues throughout the production process. These include broken needles in knitting applications, thread breakage during weaving and visible defects in the final product after dyeing. Effective contamination clearing substantially enhances yarn quality, but overly stringent measures can negatively impact production efficiency and increase waste.

Humidity fluctuations

Prisma P-clearing balances the need for quality yarns with maintaining operational efficiency. Loepfe’s approach combines advanced technology, precise signal processing and tailored settings to address various production scenarios, now enhanced to account specifically for humidity fluctuations.

Prisma now features an innovative climate compensation setting and extensive testing at affected spinning mills has demonstrated several benefits, including enhanced overall classification accuracy, improved clearing performance, consistent cut rates and superior final fabric quality, with the same cuts and better clearing performance.

The new function makes it easy to counteract the changing climate in a spinning mill and then takes into account the increasing humidity and calculates an average value between the standard deviation and the peak values.

P-Clearing Matrix

The P-Matrix allows operators to input specific parameters, starting with a pre-generated clearing curve by the Autostart function that considers the most crucial factors for optimal and efficient clearing results. By easily adjusting the settings – raising or lowering the clearing curve – operators can tailor outcomes to meet their individual production needs.

The key influences on polypropylene clearing include fibre length and short fibre content, yarn count, the amount of twist in the yarn, yarn hairiness and humidity’s impact on hairiness.

The Climate Compensation value may be influenced by the yarn count and cotton variety. It is recommended to use a value of 50% as a starting point, since various trials show that the best results can be achieved between 35% and 75%.

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