Comparison between Basic Structures of Weft Knitted Fabric

All weft knitted fabric structures are classified into four basic groups according to the arrangement of loops in their courses and wales. Four primary structures plain, rib, interlock and purl are the base structures from which all weft knitted fabrics are derived. A short introduction of four primary structures are given below.
Weft knitted fabric structures
Fig: Weft knitted fabric structures
Plain structure:
The simplest and most basic structure is the “plain knit” which is also called “single knit”. Plain is a knit structure family, which is produced by the needles of only one set of needle with all the loops intermeshed in the same direction. Although the plain knit family encompasses a great number of structures all produced on a single needle bed.

Rib Structure:
Rib, also called “Double-knit” is the second family of knit structures. Rib requires two sets of needles operating in between each other so that wales of face stitches and wales of back stitches are knitted on each side of the fabric. Many types of rib structures can be produced according to the arrangement of active needles in the front and back needle beds.

Interlock structure:
The interlock structure is a variant of the rib form in which two threads are alternately knitted by the opposite needles so that interlocking occurs. Interlock is an interlocking of two 1 x 1 rib structures in such a way that the face wale of fabric “1” is directly in front of the 'reverse wale' of the rib fabric “2”.

Purl structure:
Purl knit structures is the third family of knit structures. In the purl fabric structure, loops are drawn to opposite sides of the fabric, which, on both sides, has the appearance of the back of a plain stitch fabric.

Comparison between basic structures of weft knitted fabric:
In the table we have shown plain, rib, interlock and purl fabric structures.
Properties
    
Plain
Rib
Interlock
Purl
Appearance
Different on face & back; V-shapes on face, arcs on back
Same on both sides, like back of plain
Same on both sides like face of plain
Same on both sides, like back of plain
Unroving
Either end
Only from end knitted last
Only from end knitted last
Either end
Curling
Tendency to curl
No tendency to curl
No tendency to curl
No tendency to curl
Thickness & warmth
Thicker & warmer than plain woven made from same yarn
Much thicker & warmer than plain
Very much thicker & warmer than plain
Very much thicker & warmer than plain
Extensibility
Lengthwise
Widthwise
Area

Moderate (10-20%)
High (30-5-%)
Moderate-High

Moderate
Very high (50-100%)
High

Moderate
Moderate
Moderate

Very high
High
Very high


End-uses

Basic T-shirt (men's and ladies), Ladies stockings, fine cardigans, dresses, base fabric for coating, fully fashioned knit wear etc.
Socks, cuffs, waistbands, collars,
underwear, knitwear.
Underwear, shirts, suits, sportswear, trouser suits, dresses.


Children’s clothing, knitwear, thick and heavy outerwear.