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Filament twisting is used in composite applications for various purposes, e.g. protection twist in downstream processes, or to produce hybrid yarns combining different yarn materials for high-performance parts like friction products.
MARKUS BECKMANN VICE PRESIDENT PRODUCT MANAGEMENT VOLKMANN PRODUCT LINE OERLIKON SAURER(published on April 2010 - JEC Magazine #56)
Oerlikon Saurer is a business unit in the textile segment of the global technology group, OC Oerlikon. With groundbreaking technological innovations and its Allma and Volkmann product lines, Oerlikon Saurer is a major international supplier of twisting and cabling systems.
The Allma product line has been setting new technological milestones in twisting technology for several decades, especially for tire cord and technical yarns. The Volkmann twisting machines have been used in the staple-fibre-yarn, glass-filamentyarn and carpet-yarn market segments, in close cooperation with the company’s customers, for more than 100 years.
Glass-filament yarn twisting
The market for twisted-glass-filament yarns is constantly growing and full of innovations, mainly for printed boards (Fig. 2), but also in special applications. It has a promising future for products which do not yet exist. Minimum electrical conductibility and resistivity make textile glass ideal for use in the electronics industry. Advanced production systems are a basic prerequisite in the manufacture of twisted-glass-filament yarns for this highly dynamic market.
Besides existing customer requirements such as reliability, yarn quality and cost-effectiveness, new parameters are gaining importance in glass-filament production: a high technological standard, performance, and ergonomic innovations are contributing significantly to its success.
The Volkmann product line achieved a major breakthrough with the development of the new Volkmann GT (GlassTwister) (Fig. 1). This innovative, high-performance ring twisting machine has really proven itself in the market and has set new standards with its technological features. Among these are state-of-the-art drive components for the creel baskets, ring rail and ring twisting spindles, central setting via touchscreen plus the constant monitoring of process parameters and production data, and a host of further elements. The result is first-class glass-filament and bobbin quality.
Ring twisting technology
The Volkmann GT has a unique ring rail drive (Fig. 3), which operates without counterweights and therefore has low mass moments of inertia, ensuring precise package build-up. Due to a physically improved yarn path throughout the twisting process, smaller deviation angles allow extremely gentle yarn treatment and fine yarn processing at the highest possible speeds. Low yarn tension and very low peak forces ensure best yarn quality, e.g. fewer filament breaks. Spindle and basket speed for yarn delivery, twist insertion and package winding are controlled by state-of-the-art spindle motors and frequency inverters.
High-quality glass-filament yarns with protection twist demonstrate advantages for subsequent process steps like beaming, coating and weaving. In weaving, processability is enhanced due to the closed yarn shape, which results in higher efficiency and high-quality products. As the twister’s final product, the package build-up determines the unwinding performance and economical situation of beaming as the necessary step for weaving preparation.
Capstan delivery system
With the optionally available capstan delivery system (Fig. 4), feed packages can be processed into multiple yarns coming from an independent creel. The capstan delivery system ensures a smooth and equalizing feeding of the different yarn components. This is an important factor, especially for glass twists, but also for hybrid twists. Typical applications are glass twists for sewing threads, twists made of coated glass yarns, hybrid twists made of copper, glass and polyacrylics for coupling coatings, etc.
A closed drying system is also available for effective yarn drying down to a residual moisture of 0.1%.
This process is also controlled by frequency inverters.