Yarn classification according to their structures:
These yarns are made from short and staple fibers. Staple fibers are converted to yarn by twisting. There are different kinds of spinning systems; like ring, open end and air-jet systems. Each of mentioned systems can give unique properties to yarn.
When we say ring yarn; that means this yarn is made by ring spinning system.
We can produce combed yarn and card yarn by the ring system, it should be stressed that combed yarn has better mechanical properties than card yarn; it is finer and has better tensile strength because it has lower amount of short fibers in its structure. In spun yarns the amount of twist per inch and its direction (z-s) are so important.
Filament yarns are made by two; melt spinning or solution spinning processes and divides into two groups:
Mono-filament yarns: these yarns are made of relatively thick filament, which contains only one filament.
Multi-filament yarns: These yarns are made of two or more filaments which doesn't need twisting or if it does; the amount of twist is low.
The first group which mentioned above usually is single twisted yarn which is used for producing ordinary fabrics and garments, but ply yarns are made of two or more single yarn. Ply yarns have higher modulus and strength for different kinds of usages like industrial, technical and producing garments.
Two-ply yarns are made by twisting two single yarns.
Three-ply yarns are made by twisting three single yarns.
Four-ply yarns are made by twisting four single yarns.
By twisting two or more ply yarns we can produce cord yarn which has high strength and by twisting two or more cord yarns we would produce rope yarn
Classification by application:
Generally yarn is used for weaving, knitting and as sewing thread.
Weaving: in weaving process we use yarns as warp and weft. Warp yarn has higher strength, tighter twist and smoother surface than weft yarn which is used in width of fabric.
We do knitting process by hand or by machine. The yarn which is used for knitting is more slackly twisted than weaving yarns.
For machinery process we can use single or ply yarns and for hand knitting we use ply and novelty yarns.