芯紗的結構包括兩種織維，一是在紗中心部份，另一種織維是包覆在外層；一般芯紗中心材料是採用人織長絲，而包覆在芯外層是採用短織包紡製。在目前多是以環錠精紡機來生制造，而此種絲棉混紡的芯紗及布，主要用於改良傳統混紡紗，布的強伸度、耐磨性等物性。
用傳統環錠精紡機紡製芯紗需要三對羅拉的牽伸系統及一餵絲製置，在短織供應系統，可用一根或兩根粗紗餵入，若用兩根粗紗時，必需注意其掛紗及穿紗餵入位置，而長絲經由導紗張力機構，由前羅拉上皮輥固定位置餵入，與被牽伸後之粗紗短織混合，並嵌入紗之中心，形成芯紗。在芯紗成形時之導紗橫動位置淌需與領，導紗鈎之昇降動程同步配合。
在本研究中，初步芯紗中心，主要選用聚酯絲，而包覆外層短織選用純棉精紗紡製。主要工作在變化絲與棉混合之比例、位置、絲丹尼數、撚度、張力，對其形成芯紗之物性作一分析探討。
Core yarns are structures consisting of two component fibers, one of which forms the center axis or core of the yarn, and the other the covering. Generally, the core is a continuous multifilament yarn, while staple fibers are used for the outer covering or sheath. The process is readily adaptable to conventional ring spinning frames with only minor modifications. Core yarns have been used to improve the strength, elongation, durability, and functional properties of yarn and fabrics.
A conventional ring spinning frame with a double apron drafting system was modified to accommodate the packages of filament yarn. Either Single-or double-creeled roving can be used for the cotton. If double-creeled roving is used, it is best to use a split guide to keep the individual strands of roving from crossing. The filament yarn was fed over-end from the package, through a tension control disc, and then inserted behind the top front roll directly in the center f the strand of drafted staple fibers via a porcelain guide. The traverse of the core yarn guide was synchronized with that ring and snail of the lifting system.
Our aim in this work was to develop the blending position and deniers of filament and yarn twist etc. Core yarns spun with polyester: ores and cotton wrapping were compared with similar yarns composed of cotton intimately blended with staple polyester.
