Types of Weft Knitting Machine

Types of Weft Knitting Machine
Rofiquzzaman Raju
Fabric Technologist,
B.J.Group, Mawna, Gazipur
Chittagong Textile Engineering College
Contact: 01714419681



Weft Knitting:
There are two types of knitting: weft knitting and warp knitting. In the more common weft knitting, the wales are perpendicular to the course of the yarn. In weft knitting, yarn is knitted horizontally and in a circular form. Most of the knitted fabric is produced by weft knitting. Various types of machine used for production of weft knitted fabric. In this article, all types of weft knitting machine are described with feature.
Weft knitting machine
Weft knitting machine (Circular)
Types of weft knitting m/c:
 
***According to the end product, the weft knitting m/c may be broadly classified as either:
  1. Fabric m/cs
  2. Garment length m/cs
1. Fabric Machine:
Large diameter, circular, latch needle m/cs, knit fabric, at high speed, that is manually cut away from the m/c after a conventional length has been knitted. Most fabric is knitted on circular m/cs either single cylinder or cylinder and dial.

Features of fabric m/cs:
  • Large diameter, circular, latch needle m/cs (also known as yarn goods or piece goods) knit fabric, at high speed.
  • The fabric is manually cut away from the m/c usually in roll form after a convenient length has been knitted.
  • Most fabric is knitted on circular m/cs 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
  • Sinker wheel and loop wheel frames could knit high quality specialty fabrics with bearded needles although circular m/cs employing bearded needles are now absolute, the production rates of these m/cs were uncompetitive
  • Unless used in tubular body-width, the fabric tube requires splitting into open-width
  • The fabric is finished on continuous finishing equipment and is cut-and-sewn into garments or it is used for household and technical fabrics
  • The productivity and patterning facilities of fabric m/cs vary considerably.
  • Generally; cam settings and needle set-outs are not altered during the knitting of the fabric
2. Garment Length Machine:
Flat and circular m/cs, knitting garment length sequences which have a timing or counting device to initiate an additional garment length programming (m/c control) mechanism. This coordinates the knitting action to produce garment structural repeat sequence in a wale wise direction. The garment width may or may not vary within the garment length.
 
***According to their frame design and needle bed arrangement, the weft knitting m/c may be broadly classified as either:
  1. Straight bar frame m/cs
  2. Flat knitting m/cs
  3. Circular knitting m/cs
1. Straight Bar Frame Machine:
Special type of m/cs having 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 m/c. the length of the m/c is divided into a number of knitting heads.
 
2. Flat Knitting Machine:
The typical flat m/c has two stationary beds arranged in an inverted V formation. The m/cs range from hand-propelled and manipulated models to automated, electrically-controlled, power-driven m/cs.

Feature of Flat knitting m/c:
  • 2 stationary needle bed in flat knitting m/c arranged in an inverted V formation
  • Latch needle is used
  • Angular cam of a bi-directional cam system used
  • There is a separate cam system for each needle bed
  • The two cam systems linked together by a bridge, which passes across from one needle bed to the other
  • Carriage with determined yarn carrier issued
  • Cam system is attached to bottom side of carriage
  • The flat m/c is the most versatile of the weft knitting m/c
  • Fabric produce with finer to coarser yarn
  • The operation and supervision of the m/c is simple
  • The stitch length range is wide and possibly of changing the m/c gauge
  • Trimmings, edging, collars, to shaped panels and integrally knitted complex garments and other articles
3. Circular Knitting Machine:
Circular m/cs whose needle beds are arranged in circular cylinders and/or dials including latch, bearded or compound needle machinery.

Classification of circular knitting m/c:
  • Circular bearded needle single-jersey fabric machine
  • Revolving cylinder latch needle machine
  • Circular garment length machine
a. Circular bearded needle single jersey fabric machine:
Types of machines are divided into two types:-
  • Sinker wheel machine or French/Terrot type m/c
  • Loop wheel frame or English type m/c
Both of them have the following common features:-
  • Needles are fixed in a recolcing circle on needle bed
  • Knitting action is entirely achieved by ancillary elements moving yarn and loops along the needle stem
  • Here tubular fabric is knitted with its technical back facing outward
  • Low productivity but has an ability to produce unusual and super-quality knitted structures
b. Revolving cylinder latch needle machine:
There ate two main types of revolving cylinder latch needle machine, namely-
  • Open top or sinker top or single jersey m/c
  • Cylinder & dial m/c or double-jersey mc/
These machines produce most weft knitted fabrics. The open-top or single-jersey machines have one set of needles arranged in a cylinder. This one set of needle is controlled by one one set of cam. They produce plain fabric.

On the other hand the cylinder and dial m/c or double jersey machines have two sets of needles. One set on cylinder and thee other set on dial. Dial and cylinder needles stay perpendicular to one another. They one controlled by two separate set of cams, namely cylinder cams and dial cams. They are either rib or interlock type fabric producing m/c .

Machines of both types may or may not have patterning capabilities

c. Circular garment length machine:
Circular garment length machines ate generally of body width size or larger. They have a cylinder and dial arrangement or double cylinder. They also may be of small diameter hosiery type. This hosiery type small diameter machines may have a single cylinder or a cylinder and a dial or double cylinders.

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