Polyester yarns account for the majority of false twist textured yarns. The simultaneous actions of drawing (stretching), heating, and twisting on the filament bundle improve the tensile and tactile properties of continuous filament partially oriented yarns. Winding the yarn on a bobbin after untwisting results in high elasticity. Heating the yarns under controlled partial relaxation after untwisting and prior to winding on a bobbin manufactures double heater or set yarns. An overview of industrial false twist and drawtexturing processes for polyester yarns addresses creels, shafts, predraw tension, spindle tension, tension ratio, coning oil application, winding, yarn cutters, yarn transport systems, yarn displacement systems, twist stops, contact and high temperature heaters, cooling plates, twist insertion, crimping, friction discs, disc stacking, guide discs, takeup, draw ratio, package build, skein shrinkage, interlacing, cradle damping, taper angle, stroke length, bulging, overthrown ends, ridges, saddling, shouldering, yarn carriers, and package dyed yarns.