Introduction: The process by which fabric is produced by a set of connected loops from a series of yarn in a weft or warp direction is called knitting. Knitting is the method of creating fabric by transforming continuous strands of yarn into a series of interlocking loops, each row of such loops hanging from the one immediately preceding it. The basic element of a knit fabric structure is the loop intermeshed with the loops, that different from woven fabrics. Knitting is a branch of textile which has a long history. Knitted goods were reputed for centuries. Various types of design and structure fabric can be produced by knitting. In the past knitting was performed by hand. Nowadays various types of modern knitting machines are used for producing knitted fabric. These machines are highly productive and can produce various types of fabric. Here I will discuss knitting machines that are used in the modern knitting industry.
Types of knitting machine: There are two types of knitting machine
1.
Warp knitting machine
2. Weft knitting machine
1. Warp knitting: A process of knitted fabric construction by which a
set of warp yarns are simultaneously formed into loops, connected by sideways a movement that interlink the loops. In this structure, each loop in the
horizontal direction is made from a different thread and the number of threads
used to produce such a fabric is at least equal to the number of loops in a
horizontal row.
Types of warp knitting machine
a. Tricot warp
knitting machine
b.
Raschel warp
knitting machine
Majors feature of tricot warp knitting
machine:
1. In the past, tricot machines are mainly employed bearded needles with a pressure bar.
2. Tricot machine has a gauge expressed in needle per
inch and chain-link numbering
0,1,2,3,4 etc.
3. Their sinker are joined to each other at the front
and back, never move to clear off the needles as combine the functions of
holding down, knocking over, and supporting the fabric loop
4. The produced knit fabric is drawn away towards
the batching roller almost at right angles to the needle bar
5. The warp sheets pass
over the top of the guide bar rocker shaft to their tension rails which are
situated at the front of the tricot warp knitting machine.
6. Mechanical tension of
the knitting elements is carried out at the front of the machine as the beams
prevent across to the back in tricot warp knitting machine
7. The machine has a
simple construction and a short yarn path from the beam.
8 Mechanical attention to the knitting
elements is carried out at the front of the machine cause warp beams to prevent
access to the back.
9. Knitting action occurs at gentle and very low
tension.
10. As the entire warp sheets are drawn over the
rocker shaft to the machine. It is easy to thread up the guide bar indicating the needle bar.
11. In this machine, the warp beams are
accommodated in an inclined arc towards the back of the machine with the top beam supplying the front guide bar and the bottom beam supplying the back
guide bar.
12. In a tricot machine, the fine gauge is 28-44 needles
per inch (NPI)
13. Tricot machine is ideal for high-speed
production.
Features
of Raschel warp knitting machine:
1. Latch needle is used in raschel warp knitting
machine with a latch wire or blade.
2. Their chain links are usually numbered in even
numbers 0, 2, 4, 6, 8, etc. generally with two links per course.
3. Raschel machines sinkers only perform the
function of holding down the loops when the needles rise.
4. As the raschel sinkers are not joined together
by a lead across their ends near the needle bar, they can move away towards the
back of the machine for the rest of the knitting cycle.
5. The needle trick-plate verge acts as a fabric support
ledge and knock-over surface.
6. The produced fabric is drawn from the needle
almost parallel to the needle bar at an angle of 120 degrees to 160 degrees by a
series to take down rollers.
7. The guide bars are numbered serially from the
front of the machine
8. In this machine, the beams are placed above
the machine so that it is approachable at the front for the fabric inspection.
9. In this machine, the warp beams are arranged above the needle bar and centered
over the rocker shaft, so that the warp sheets pass down to the guide bars on
either side of it.
10. At least four 32” diameter beams or large numbers of small
diameter pattern bars
2. Weft knitting: A process by which a loop is formed in the weft direction by
using one thread and thread runs in a horizontal direction to form a knitted
fabric is called weft knitting. In other words, producing a knitted fabric by intermeshing
loops formed successively across the width of the fabric from a yarn fed substantially
crosswise to the length of the fabric.
Types of weft knitting machine: Weft knitting machines are divided into several ways
A. According
to the frame design and needle bed arrangement or construction:
i.
Flat knitting
machine
ii.
Circular knitting
machine
iii.
Straight bar frame
machine.
B. According to
the number of needle beds or number of needle sets used:
i. i. Single jersey knitting machine
ii. ii. Double jersey knitting machine
C. According to the end product of the weft
knitting machine:
i.
Fabric machine
ii.
Garment length
machine
D. According to the basic structure of weft knitting
i.
Plain or single
jersey circular knitting machine
ii.
Rib circular or
flat knitting machine
iii.
Interlock circular
knitting machine
iv.
Link –link or purl
flat knitting machine
A.1.Flat knitting machine:
The typical
flat knitting machine has two stationary beds arranged in an inverted V
formation. The machines are range from hand-propelled and manipulated models to
automated, electrically-controlled, power-driven machines
Feature of Flat knitting
m/c:
1. There are 2 stationary needle beds in a flat knitting machine which
are arranged in an inverted V formation
2. Latch needles are used
3. Angular cam of a bi-directional cam system is used
4. A separate cam system is used
for each needle bed.
5. The two cam systems are linked together by a bridge, which passes
across from one needle bed to the other
6. Normally machine gauge is 3 to 18 needles per inch and machine
width up to 79 inches.
7. Carriage with determined yarn carrier issued
8. Cam system is attached to the bottom side of the carriage
9. The flat machine is the most versatile of the weft knitting machine
10. Fabric produced with finer to coarser yarn
11. The operation and supervision of the machine is simple
12. The stitch length range is wide and possibly of changing the machine
gauge
13. Trimmings, edging, collars, shaped panels, and integrally
knitted complex garments and other articles.
A.2.Circular knitting machine: Circular knitting machine is one kind of weft knitting machine whose needle beds are arranged in circular
cylinders and dials, including latch, spring bearded, and very occasionally
compound needle machinery.
Feature
of circular knitting machine:
1. The circular knitting
machine has a rotating cylindrical needle bed.
2. Normally latch needles and compound needles are used.
Sometimes bearded needles and other needles are used.
3. Holding down
sinker sinkers are used for a single jersey machine, one between every needle
space
4. Stationary angular cam system is used normally for
needles and sinkers.
5. For a single jersey machine, a sinker trick ring is simply and directly attached
to the outside top of the needle cylinder.
6.
Needle retaining is used in this machine.
A.3.Straight
bar frame machine: The Straight bar knitting machine is a type of machine that has a vertical
bar of bearded needles whose movement is controlled by circular engineering
cams attached to a revolving cam-shaft in the base of the machine. The major
feature of the straight bar knitting machine is, the length of the machine is
divided into a number of knitting heads sections or divisions and each head is
capable of knitting a separate but identically-dimensioned fashion-shaped
garment panel.
B.1.
Fabric Machine: Large diameter,
Circular, latch needle machine, knit fabric, at high speed, that is manually
cut away from the machine after a conventional length has been knitted. Most
fabric is knitted on circular or cylinder and dial
Features
of fabric machine:
1.
Large diameter, circular, latch needle machine knit a machine at high speed
2.
After completing
knitting a convenient length of fabric it is manually cut away from the machine in
roll form.
3.
Most fabric is
knitted on circular machines either single-cylinder (single jersey) or cylinder
and dial (double jersey) of the revolving needle cylinder type, because of
their high speed and productive efficiency.
4.
Sinker wheel and
loop wheel frame could knit high-quality fabric with a bearded needle.
5.
Unless used in
tubular body width the fabric tube requires splitting into open width.
6.
The productivity
and patterning facilities of fabric machines vary considerably.
7.
Generally, cam
setting and needle set-outs are not altered during the knitting of fabric.
B.2.
Garments length machine: It is a flat circular machine, knitting garment
length sequences that have a timing or counting device to initiate an additional
garment length programming mechanism. The garment's width may or may not vary
from within the garment length.
Features
of garment length machine:
2. The machine control may have to initiate correctly time changes in some or all of the following: cam settings, needle set-out, feeders a machine.
3. The fabric takes a down mechanism must be more sophisticated than continuous fabric knitting.
4. Garments may be knitted to size either in tubular or open-width.