The fineness (diameter) of single filament when
combined defines denier (dtex) of filament
yarn.
Filament yarns produced through texturing are
applied heat and subsequent twisting to give
desired form to filament yarn.
Most widely used filament yarns are :
Polyester Draw Textured Yarns (DTY),
Fully drawn yarn (FDY) or Spin Drawn Yarn
(SDY),
Partially oriented yarns (POY),
Air jet textured yarns (ATY),
Nylon 6 (DTY and FDY) yarns ,
Viscose filament yarns,
Polypropylene filament yarns,
PBT (polybutylene terephthalate) yarns,
PTT (polytrimethylene terephthalate) yarns.