Fastness

See COLORFASTNESS.

Fatigue

Refers to the resistance of a material to weakening or failure during alternate tension-compression cycles i.e. in stretch yarns the loss of ability to recover after having been stretched.

FBA

A substance that when added to a substrate increases the apparent reflectance in the visible region by converting ultra-violet radiation into visible light and so increases the whiteness or brightness.

FDY

A melt-spun continuous-filament yarn that has been highly oriented either by drawing at a high draw ratio (preferred term, fully drawn yam) or by spinning at a high wind-up speed such that little residual drawability remains (preferred term, highly oriented yarn). (See also draw-twist, draw-wind, spin-drawing and draw-spinning.)
Note: These terms are used in contrast to low orientation yarn and partially oriented yarn.

Fearnought (fabric)

A stout, thick, woollen fabric with a heavy appearance, used chiefly as a covering for port-holes and the doors of powder magazines and also for scarves and coats.

Feather-edged slivers

Sliver that contains a large number of fibres projecting from the main body.
Note: During the unwinding of the sliver from the top in the creel, the projecting fibres 'click' to neighbouring slivers, which causes them to become disarranged and bent back to form neps in the subsequent products.

Feed

1. The final element which guides the yarn(s) to the needles.
2. A device which supplies yarn to the feeder (see positive feed (weft knitting)).
Note: A large diameter machine with a multiplicity of feeders may be referred to as a multifeeder machine.

Feed dog (sewing machine)

A toothed element which acts on the surface of material being sewn to move it in a controlled way during stitching. The action is normally on the lower surface of the material, but mechanisms which act on the upper surface are also in use. For most of the time, the operative motion is forwards (away from the machinist), but in specific cases (such as back tacking) the motion is reversed. (See also feed mechanisms (sewing,).)

Feed mechanisms (sewing)

The means for moving the material being stitched from one stitch position to the next.compound feedA feed mechanism comprising synchronised drop feed and needle feed.drop feed A feed mechanism in which the feed dog alternately engages and disengages the underside of the material to transport it forward.differential drop feed; differential bottom feed A type of drop feed with two feed dogs arranged in tandem to move differentially. One feed dog is in front of the needle and the other is behind. Material may be gathered or stretched by adjusting the stroke of the front feed dog so that it is longer or shorter respectively than the stroke of the rear feed dog.needle feed A feed mechanism in which the feeding of the material is accomplished or assisted by the needle which moves forward by one stitch whilst penetrating the material.puller feed A feed mechanism situated behind the presser foot and consisting of one or more rollers, at least one of which is driven, in contact with the material. Puller feeds may be either continuous or intermittent, and may be used in conjunction with other feed mechanisms.top feed A feed mechanism in which apresser foot, known as a 'feeding foot', alternately engages and disengages the upper surface of the material to transport it forward. adjustable top feed; variable top feed A top feed system with the presser foot in two sections: one of which holds the material in position during needle penetration whilst the other, with its teeth on the lower side, engages the upper ply to feed the material forward when the needle is raised. top and bottom feed A feed mechanism in which top feed and drop feed work in unison. unison feed A feed mechanism providing needle feed in addition to the top and bottom feed. wheel feed A feed mechanism in which a driven wheel or roller, in constant engagement with the material, replaces all or part of the normal presser foot or feed dog. It is described as ,upper-feed' or 'under-feed' wheel according to its position relative to the material. The feed may be continuous or intermittent.

Feed roll

A roller that forwards a yarn to a subsequent processing or take-up stage.

Feed roller

A roller that forwards a yarn to a subsequent processing or take-up stage.

Feeder (circular weft-knitting machines)

1. The final element which guides the yarn(s) to the needles.
2. A device which supplies yarn to the feeder (see positive feed (weft knitting)).
Note: A large diameter machine with a multiplicity of feeders may be referred to as a multifeeder machine.

Feeder (knitting)

An element which guides the yarn.

Feeder variation

A fault, affecting all the stitches in a course in a knitted fabric on a multi-feeder machine. It recurs in all the courses knitted by a particular feeder.

Feeding foot

A feed mechanism in which apresser foot, known as a 'feeding foot', alternately engages and disengages the upper surface of the material to transport it forward.(sub Category of feed mechanisms(sewing))