Introduction to Textile Fabric
Part 3: Double Knit Structures
Dr. Jimmy Lam
Institute of Textiles & Clothing
The Hong Kong Polytechnic University
Content
• What is double knit fabrics
• Characteristics of double knit
fabrics
• Examples of double knit fabrics:
– 1X1 Rib, 2 x 2 rib, half cardigan, full
cardigan, half milano and full milano.
• Interlock Fabric
• Modified interlock fabrics
Double Knit Fabric
•
•
Double knit fabrics or double jersey
are knitted fabrics produced by
machines using two set of needles.
They can be produced by:
1. Rib and non-jacquard machines
2. Interlock machines
General Characteristics
(Double knit fabrics)
• 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.
• Balance of structure
– As double knit fabrics have loops on both
sides, curling is not so worse as single knit
structure.
General Characteristics
(Double knit fabrics)2
• 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:
•
•
•
•
Yarn count and machine gauge;
Fabric structure;
Stitch density and
Type of finish.
• 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 nonjacquard structures
The rib structure
• All structures of this group are
produced by two sets of needles with
the opposite needles off set for half a
needle space;
• Ie. The head of the needles are not
directly facing each other.
Rib Gating
Example of double knit
fabric : 1x1 rib
• This is the most simple
double knit structure. It
can be made on V-bed
knitting machine and
circular rib machine.
• 1x1 rib fabric is one course
per repeat structure.
• Both face and back looks
exactly the same.
Characteristics
of 1x1 rib
• The 1x1 rib is a perfectly balanced
structure.
• 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.
• The elastic recovery of 1x1 rib fabric is
exceptionally high along the width.
• When relaxed the fabric shrunk so much
that only the technical face loops can be
seen on both sides.
End uses of
1x1 rib
• 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.
• 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.
• 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
• Similar to 1x1 rib, this is also an one
course per repeat structure.
• The main difference is that it is composed
of 2 technical face loops and 2 back loops
per repeat along the course.
• The 2x2 rib is most popular for the cuffs
and waist bands for the coarse gauge
knitwears.
2x2 rib
2x2 ribs
• There are two methods to
produce 2x2 ribs on knitting
machine
• Method 1: with every 3rd
needles out of action
• Method 2: with every 3rd and
4th needles out of action.
2x2 rib
• The fabrics produced from these two
methods are more or less the same.
• Method 1, however, gives a tighter fabric
and more elastic fabric.
• This method is used on circular rib
machine and V-bed machine. Sometimes,
the rib is called 2x1 rib
• 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.
Yarn Path Notation
The broad ribs
(fancy ribs)
• Any rib which is wider than 2x2 rib can be
classified as broad ribs or fancy ribs.
• Example the Derby rib which is 6x3 rib is
generally used on the pullovers.
• Fancy rib can be of any combination in face
and back wales, such as 10 x5; 20 x 4 etc
Fancy Rib (broad rib)
Discussion
• What is double knit fabric?
• Which fabric is more elastic, plain or
1x1 rib fabric?