Owing to growing demand for figure hugging and comfortable clothes made with stretchable fibers, spandex fibers are being used in underwear, diapers, hosiery, leisurewear, sportswear, jeans, and so on. In the present study a polyester core-spun yarn containing spandex fibers was made using a self-designed, multi-section drawing frame and a ring spinning frame. The mechanical properties of the core-spun elastic yarns were examined in various processing conditions. The analytical results show that when the main drawing ratio of the spandex fibers was either 2.2 or 2.7, the maximum breaking tenacity and elongation of the core-spun elastic yarns exceeded those in any other of the main drawing ratio conditions. Demand for elastic fibers is still growing. Consumption of elastic fibers reached 137,000 tons in Asia in 2001. Bayer in Germany was the first to develop polyurethane elastic fibers. US scientists began to develop the commercial applications of polyurethane from the 1940s. Soft and flexible elastomer or hard and abrasion-resistant materials can be fabricated with polyurethane. Spandex fibers are long-chain polymer fibers containing at least 85% segmented polyurethane [2]. Spandex fibers have been developed and produced by numerous companies, for example Spanzelle, Vyrene, Lycra, Glospan, etc.Various previous studies have reported the physical and chemical properties of spandex fibers. An elastic fiber has been characterized by high breaking elongation (exceeding 100% and generally 500 to 800%), a low modulus of elasticity (approximately 1/1000 that of a conventional "hard" fiber, such as nylon, cotton, and so on), and both a high degree and a high rate of recovery from 100% stretching (about 95%). Spandex fibers are resistant to hydrolysis (Lycra had power retention of 100% after boiling for 1 hour in water at pH 3 to 11). In addition the spandex fibers have good resistance to ultraviolet radiation, oxygen, heat, and oil [5]. Babaarslan described a method of producing a polyester/viscose core-spun yarn using spandex fibers. The spandex fibers (Lycra) were covered with polyester staple fibers of 38 mm and 1.3 dtex and viscose staple fibers of 38 mm and 2.4 dtex using a modified ring spinning frame with a positive feed roller system and a V-groove guide. The mechanical properties of the yarn and its uniformity were examined. The corespun yarns had lower tenacity than polyester/viscose staple yarns, but they had higher elongation [1]. Previously, several investigators have studied core-yarns containing a nylon or polyester filament [3,4,6,7].Nowadays, the textile industry is producing various core-spun yarns with spandex fibers of 22 to 156 dtex. The spandex fibers covered with staple fibers can be used for daily commodities and industrial products. This work made a polyester core-spun yarn from spandex fibers using a self-designed, multi-section drawing frame and a ring spinning frame. To keep their elas-
