86 NEW DEVELOPMENT IN THE CORE YARNS MANUFACTURE F. Marsal 1 , D. Palet 1 , M. Riera 1 , A. Serra 2 , L. Indrie 3 , M. Ratiu 3 1 Technological Innovation Centre CTF . Technical University of Catalonia, Terrassa, SPAIN 2 Pinter, S.A. Santpedor, SPAIN 3 Faculty of Textiles and Leatherwork. University of Oradea, Oradea, ROMANIA Corresponding author: Feliu Marsal, marsal@etp. upc.edu Abstract : A new mechanism for the regulation of feeding tension of elastic filaments has been de veloped, in cooperation with a reputable manufacturer of textile machinery, to obtain “core spun” yarns. This device reduces, of a very significant form, the coefficient of variation of the elongation of the yarn and, consequently, the fabrics obtained with this yarns are more regular appearance . This mechanism is fundamental when the new spools of T-400, with diameter and weight superiors to the standard size, are processed. Keywords: Core yarn. New device. Feed tension control. T -400. 1. INTRODUCTION In the manufacture of “core spun” yarns (1), or the yarns constituted by a nucleus of elastic filament or elastomer, surrounded by a natural or chemical staple fibres, nowadays has originated a problem due to the tendency, every day increased, to use elastomer spools of dimensions and weights superiors to the standard size. (Figure 1). Figure 1: Left: standard spools. Right: New spool On the one hand an increase of productivity, in significant form, is obtained due to the reduction of number of changes of elastomer spool during the spinning process; but on the other hand the high diameter and weight of these new spools, 260 x 150 mm and 4400 g of weight, in front of the 600 g and 57 x 165 mm of the conventional spools cause problems for the control of the feeding tension, mainly when the diameter of the spool is reduced due to its consumption during the spinning operation. It causes, especially, irregularities in the yarn that will give rise to faults in the weaving process, mainly bars and differences of color in the dyeing. These problems are more importants when ANNALS OF THE UNIVERSITY OF ORADEA FASCICLE OF TEXTILES- LEATHERWORK Volume I, 2010, No. 2