Introduction to Textile Fabric Part 3: Double Knit Structures Content

Introduction to Textile Fabric
Part 3: Double Knit Structures
By Hammad Mohsin
University of Management and Technology
Spring 2010
Courtesy: Dr. Jimmy Lam
Institute of Textiles & Clothing
The Hong Kong Polytechnic University
Content
zWhat is double knit fabrics
zCharacteristics of double knit fabrics
zExamples of double knit fabrics:
{1X1 Rib, 2 x 2 rib, half cardigan, full
cardigan, half milano and full milano.
zInterlock Fabric
zModified interlock fabrics
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Double Knit Fabric
z Double knit fabrics or double jersey are
knitted fabrics produced by machines
using two set of needles.
z They can be produced by:
1. Rib and non-jacquard machines
2. Interlock machines
General Characteristics
(Double knit fabrics)
z Fabric Appearance
{It takes two set of needles to produce a piece of
double knit fabric; each set of needles produce
their own loops on one side of fabric.
z Balance of structure
{As double knit fabrics have loops on both sides,
curling is not so worse as single knit structure.
2
General Characteristics
(Double knit fabrics)2
z Fabric Weight and thickness
{ Double knit fabrics are generally heavier and thicker
than single knit fabrics because the number of loops
per unit area is much more on double knit fabrics.
{ Factors affect the fabric weight and thickness are:
z Yarn count and machine gauge;
z Fabric structure;
z Stitch density and
z Type of finish.
z Fabric elasticity
{ The elasticity of double knit fabrics is mainly affected
by their structures. Normally double knit fabrics are
more elastic than single knit fabrics.
The rib and non-jacquard
structures
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The rib structure
z All structures of this group are produced
by two sets of needles with the opposite
needles off set for half a needle space;
z Ie. The head of the needles are not
directly facing each other.
Rib Gating
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Example of double knit fabric : 1x1 rib
z This is the most simple
double knit structure. It can
be made on V-bed knitting
machine and circular rib
machine.
z 1x1 rib fabric is one course
per repeat structure.
z Both face and back looks
exactly the same.
Characteristics
of 1x1 rib
z The 1x1 rib is a perfectly balanced structure.
z The torque in the yarn is neutralized by the
loops forming on the two side of the fabric
alternatively; no curling will occur on the edge.
z The elastic recovery of 1x1 rib fabric is
exceptionally high along the width.
z When relaxed the fabric shrunk so much that
only the technical face loops can be seen on
both sides.
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End uses of
1x1 rib
z Underwears
{ It is common to use this structure for men’s underwear such as
the vest, knitted on 16 gauge with 20Ne cotton
{ This gives a light weight and elastic fabric of 100-120 g/m2.
z Sweater
{ In the cut and sewn knitwear group, 1x1 rib of the medium
gauges (7-12) knitted on wool or acrylic yarns are for ladies’
jumper. For example 2/32 Nm acrylic yarn on 12 gauge machine.
z Waist Band
{ The rib cuff, waist band or neck strap of the sweaters are usually
1x1 rib structure.
{ All the rib top of socks are 1x1 rib plus rubber inlay.
Examples of double knit
2x2 rib and broad ribs
z Similar to 1x1 rib, this is also an one course per
repeat structure.
z The main difference is that it is composed of 2
technical face loops and 2 back loops per repeat
along the course.
z The 2x2 rib is most popular for the cuffs and
waist bands for the coarse gauge knitwears.
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2x2 rib
2x2 ribs
z There are two methods to
produce 2x2 ribs on knitting
machine
z Method 1: with every 3rd
needles out of action
z Method 2: with every 3rd and
4th needles out of action.
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2x2 rib
z The fabrics produced from these two methods
are more or less the same.
z Method 1, however, gives a tighter fabric and
more elastic fabric.
z This method is used on circular rib machine and
V-bed machine. Sometimes, the rib is called 2x1
rib
z Method 2 is a true 2x2 rib and is used on purl
machine and double cylinder only.
Yarn Path diagrams
This is another method to represent the
loop formation sequence of a knitted
fabric.
The yarn path diagram is very easy to
understand, especially when it is used
on double knit structures.
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Yarn Path Notation
The broad ribs
(fancy ribs)
z Any rib which is wider than 2x2 rib can be
classified as broad ribs or fancy ribs.
z Example the Derby rib which is 6x3 rib is
generally used on the pullovers.
z Fancy rib can be of any combination in face and
back wales, such as 10 x5; 20 x 4 etc
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Fancy Rib (broad rib)
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