The needles are the most important stitch forming elements. They are displaced vertically up and down and are mounted into the tricks or cuts of the knitting cylinder. There are three types of needles namely:

We can divide a needle into three main parts:

The sinker is the second primary knitting element. It is a thin metal plate with an individual or a collective action operating approximately at right angles from the hook side of the needle bed, between adjacent needles. Sinkers capable of producing loop fabric are well known in the knitting industry. In such machines the sinkers generally include a blade having an upper edge which defines a lower knitting level and a nib having an upper edge which is at an upper knitting level. Long loops are formed at the upper knitting level of the sinkers with a loop yarn and a base yarn is knitted over the blade. The sinkers may be formed and their movement controlled to cause either the loop yarn to appear on one side of a fabric and the base yarn on the other or the loop yarn to appear on both sides. In the past it has not been possible to producing loop cloth of ideal quality since loops would twist or coil making it difficult to finish a loop fabric into satisfactory velor. Furthermore loops which were supposed to appear on the front of a fabric would sometimes appear on the other side. The back of loop cloth was therefore apt to have objectionable loose protruding loops and double tuck stitches.

In circular knitting machines of the rotatable cylinder type a well know means for selectively actuating the knitting instrumentalist is that of a pattern controlled slider jack system. Engaged the known type of slider jack system it is common practice to transmit the dictates of the pattern controlled slider jack directly to a needle actuating jack. Circular knitting machines which utilize a slider jack system must have a cylinder of sufficient length to accommodate the circular series of needle, needle actuating jacks and slider jacks which are slid ably mounted in the slots formed on the periphery of said cylinder. The slider jack must be raised a sufficient distance so as to raise the needle actuating jack or intermediate jack to a level where its operating butt will be engaged by a cam member and raise said jack to knitting height which in turn will raise its respective needle to the required height to perform its intended function.

Dial is the upper steel needle bed used in double knit machines. Into the grooves of the dial, the needles are mounted horizontally and are allowed to move radially in and out by their dial cams. The number of grooves per unit space conforms to the cylinder gauge in most of the cases.

The cylinder is a steel circular bed having grooves/tricks/cuts on its outer periphery into which the needles are mounted. With reference to the tricks, the needles move vertically up and down by their butt being in contact with the cam track. The number of tricks per inch i.e., number of needles per inch decides the gauge of the machine. Machines are built as low as 4 NPI to as high as 32 NPI. Based on the machine gauge, the fineness of the yarn to be knitted can be varied. The diameter of the cylinder also varied based on the type and width of the fabric and a maximum of 75 cm diameter machines are available.

The knitting cams are hardened steels and they are the assembly of different cam plates so that a track for butt can be arranged. Each needle movement is obtained by means of cams acting on the needle butts. The upward movement of the needle is obtained by the rising cams or clearing cams. The rising cam places the needle at a certain level as it approaches the yarn area. Cams controlling the downward movement of the needles are called stitch cams. The stitch cam draws the needle down below the knitting level, thereby drawing a loop formed by the fed yarn through the loop already on the needle. The lowest point to which the needle is drawn by the stitch cam is called the "cast-off" position. They are screwed to the cylindrical cam ring and are adjustable in vertical direction. If the stitch cam is raised, then shorter loop is drawn below the sinker level and a tighter fabric will result. With lowering of stitch cam, a reverse result is obtained. Guard cams keep the needle butts in their race-way. Running cams or the needle butts at a low level until they meet the next rising cam.

Feeders are the yarn guides placed close to the needles to the full circumference of the knitting zone. The feeders feed the yarn into the needle hooks and control the needle latches in their open position while the needle attain their clearing position. They consist of a yarn guiding hole and a bevel edge to guard the latches of the approaching needles. They are slightly curved to the corresponding curvature of the needle bed. Feeders may have two holes also for the purpose of plating. Yarn feeders can be divided into “positive” or “negative” types depending on the possibility of controlling the yarn feeding speed and uniformity. The feeder brackets can be adjusted to set their distance from the needle and to ensure yarn feed into needle hooks. Stripers are the feeders designed to deliver two or more yarns individually to the same feed. They can be considered as moving guide replacing the holes of fixed guides. In a two color stripe, two different colored yarns are supplied by two stripper fingers and their engagement is controlled by an endless control chain which governs the guide change at the appropriate feeds. At each revolution, a counter may select the movement of all the striper chains. The stripes are used on both single and double bed machines.

Chemical Properties:

Acids: Viscose rayon is damaged by strong acids but it is moderate with weak acids.

Base: Good resistance to weak alkalis but strong alkali is harmful for viscose rayon.

Effect of bleaching: Strong oxidizing agents damage the viscose rayon fiber.

Organic solvent: Viscose rayon fiber has enough ability to protest the action of organic solvents.

Protection ability against mildew: Not good and mildew damages the rayon fiber.

Protection ability against insects: Viscose rayon is affected by insects and they cause harm to the                                                               fiber.

Dyes: Viscose rayon could be dye with direct, vat and sulphur dyes.

Matthew Townsend, a Leicester hosier, patented the latch needle in 1849.  Townsend spent much of his time developing new knitted fabrics and he investigated a simpler way of knitting purl fabrics.  Purl fabrics required two beds of bearded needles and pressers to alternate the face of loops between courses.  A double-headed latch needle was developed as a result of the research to allow the alternation to be achieved on one bed of needles.  A single-headed latch needle was also developed to provide an alternative to the bearded needle.The latch needle knitting cycle starts with the old loop trapped inside a closed latch.  The needle is pushed up and the old loop slides down the stem, opening the latch in the process.  A thread is then laid in front of the stem between the rivet and the hook.  As the needle is pulled down the hook catches the thread and forms a new loop.  The old loop now slides back up the stem, closes the latch and falls off the end of the needle.  The cycle is then repeated. Latch Needle is mostly used needle in the knitting industry today. Latch needle were used on raschel and crochet machines.

The knitting action of the latch needle

Figure  shows the position of a latch needle as it passes through the cam system, completing one knitting cycle or course as it moves up and in its trick or slot.

1. The rest position: The head of the needle hook is level with the top of the verge of the trick. The loop formed at the previous feeder is in the closed hook. It is prevented from rising as the needle rises, by holding-down sinkers or web holders that move forward between the needles to hold down the sinker loops.

2 Latch opening: As the needle butt passes up the incline of the clearing cam, the old loop, which is held down by the sinker, slides inside the hook and contacts the latch, turning and opening it.

3 Clearing height: When the needle reaches the top of the cam, the old loop is cleared from the hook and latch spoon on to the stem. At this point the feeder guide plate acts as a guard to prevent the latch from closing the empty hook.

4 Yarn feeding and latch closing: The needle starts to descend the stitch cam so that its latch is below the verge, with the old loop moving under it. At this point the new yarn is fed through a hole in the feeder guide to the descending needle hook, as there is no danger of the yarn being fed below the latch. The old loop contacts the underside of the latch, causing it to close on to the hook. 5 Knocking-over and loop length formation. As the head of the needle descends below the top of the trick, the old loop slides off the needle and the new loop is drawn through it. The continued descent of the needle draws the loop length, which is approximately twice the distance the head of the needle descends, below the surface of the sinker or trick-plate supporting the sinker loop. The distance is determined by the depth setting of the stitch cam, which can be adjusted.

Compound Needle consists of two separately controlled parts; these are- the open hook and the sliding closing element (tongue, latch, piston, and plunger). The two parts rise and fall as a single unit but at the top of the rise, the hook moves faster to open the hooks and at the start of the fall the hook descends faster to close the hook. It is easier to drive the hooks and tongues collectively form two separate bars as in warp knitting; than to move each hook and tongue individually as in weft knitting. Compound needles were used on tricot machines.

The tubular pipe needle has its tongue sliding inside the tube of the open hook. The open stem “Pusher type” or slide needle has a closing wire or tongue that slides externally along a groove on the edge of the flat hook member.

A fine steel needle for machine knitting that has a butt at one end and a long, flexible hook at the other that curves back to the shank of the needle. Also known as spring needle. Bearded needles were used on tricot machinesA bearded needle shown with the beard in the open and closed positions. The needle consists of five main parts. 

Stem: The stem of bearded needle around which the needle loop is formed.

The Head: In the head section of bearded needle, the stem is turned into a hook to draw the new loop through the old loop.

The Beard: The beard is the curved downwards continuation of the hook that s used to separate the trapped new loop inside from the old loop.

The Eye or Groove: The eye of groove cut in the stem to receive the pointed tip of the beard when it is pressed.

The shank: The shank of bearded needle may be bent for the individual location in the machine or cast with others in a metal lead.

The knitting action of the bearded needle has been illustrated in Fig. Depending upon the machine, the needles are set vertically or horizontally. The needle has the disadvantage of requiring a pressing edge to close the bearded hook and enclose the new loop. The presser may be in the form of a bar, blade, verge or wheel, with either the presser or the needle remaining stationary whilst the other element moves towards it.Another feature of bearded needle knitting is that individual loop formation has to be achieved by a loop forming element. This leads to a more complicated knitting action but also provides for a more gentle and careful loop formation.

Selvedges provide strength to fabric for safe handling of the fabric. Selvedge should not curl. In shuttle looms, there is no need for special selvedges; since the yarn is not cut after each filling insertion, the edges of the fabric are smooth and strong.

In shuttle-less weaving, since the pick yarn is cut after every insertion, there is fringe selvedge on both sides of the fabric. In this case, special selvedges are needed to prevent slipping of outside warp yarns out of the fabric. There are several types of selvedge designs that are used for this purpose with shuttle-less looms. The weaving machines need mechanisms which through the formation of sufficiently strong selvedges bind the wefts together, thus imparting to the fabric a proper appearance and solidity and preventing the breaking up of the threads on the fabric edges during the subsequent operations.

Tucked-in selvedges:

A special hooked needle driven by a cam produces, after cutting, the insertion of the protruding thread end into the subsequent shed, thus forming a stronger edge. Tucked-in selvedge can be formed by two different methods. With most common method the projecting weft tail is tucked in the form of a hairpin to a predetermined length (10-15 mm) into the next weave shed. This gives a firm & neat selvedge. A 2/1 or 3/1 rib with two ends per heald & 2 fold yarns with about 20% finer than the body yarn number give excellent results. Sulzer Bros. were the pioneer to introduce this type of tucked – in selvedge on their projectile machines but now-a-days it is also used on rapier & air-jet weaving machines.

This system is generally used for light to middle weight fabrics, when weave and fabric density permit. There are also available tuck-in selvedge motions which are entirely controlled by pneumatic or mixed pneumatic and mechanical devices.

The leno gauze system is optimally suited for heavy fabrics, blankets, wall coverings. Fig. A illustrates the operation scheme of the device proposed by a manufacturer, in which device two complete leno gauze mechanisms work in combination. A leno device produces the fabric selvedge, while the other device forms the auxiliary selvedge.

Chain stitch edges:

Chain Stitch edge are produce mostly on shuttle-less narrow fabric weaving machine weaving machine in which the pick is inserted by means of a needle. These machines run at a very high speed & the mechanism for forming chain does not affect high production operation. The chain stitch has not yet been used on wide weaving machines.

Fused selvedges:

These are obtained by pressing a hot mechanical element on the fabric edge; this method can be applied on fabrics in man-made fibres. Sometimes used to split wider fabrics in to narrow width fabrics.

Melt Selvedge:

This type of selvedge is also known as fused selvedge. The formation of this selvedge requires outermost ends of thermoplastic filament yarns e.g. polyester, polyamide polyolefin etc; with this method the edge ends are plasticized by means of an incandescent pin or ultrasonic & stuck together to produce a firm neat edge which does not curl up. This type of selvedge can be used with all types of weaving machines. This also requires dummy selvedge, so the wastages are high up to 2-4% depending upon the number of ends & width of fabrics.

All these three systems allow the formation also of centre or ″ split ″ selvedges, when several lengths of cloth are woven on the same machine. 

The process of producing a fabric by interlacing warp and weft threads is known as weaving. The machine used for weaving is known as weaving machine or loom. Weaving is an art that has been practiced for thousands of years. The earliest application of weaving dates back to the Egyptian civilization. Over the years, both the process as well as the machine has undergone phenomenal changes. As of today, there is a wide range of looms being used, right from the simplest handloom to the most sophisticated loom.

Weaving machines are classified according to their filling insertion mechanism. The classification is as follows:

In shuttle weaving, a shuttle that traverses back and forth across the loom width, inserts the filling. Shuttles can be made of wood or plastic. Filling yarn is wound on the quill and the quill is placed in the shuttle. As the shuttle move across the loom, the filling yarn is unwound from the pirn and lay in the shed.

Projectile Weaving

Projectile weaving machines use a projectile equipped with a gripper to insert the filling yarn across the machine. The gripper projectile draws the filling yarn into the shed. The Projectile glides through the shed in a rake- shaped guide. Braked in the receiving unit, the Projectile is then conveyed to its original position by a transport device installed under the shed.

In Rapier weaving, a flexible or rigid solid element, called rapier, is used to insert the filling yarn across the shed. The rapier head picks up the filling yarn and carries it through the shed. After reaching the destination, the rapier head returns empty to pick up the next filling yarn, which completes the cycle. A rapier performs a reciprocating motion.

Rapier weaving machines can be of two types:

1. Single Rapier Machines: A single, rigid rapier is used in these machines. The rigid rapier is a metal or composite bar usually with a circular cross section. The rapier enters the shed from one side, picks up the tip of the filling yarn on the other side and passes it across the loom width while retracting. Therefore, a single rapier carries the yarn in one way only and half of the rapier movement is wasted. Also there is no yarn transfer since there is only one rapier. The single rapier’s length is equal to the width of the loom.

2. Double Rapier Machines: Two rapiers are used in these machines: one rapier, called the giver, takes the filling yarn from the yarn accumulator on one side of the loom, brings it to the center of the machine and transfers it to the second rapier which is called the taker. The taker retards and brings the filling yarn to the other side. Similar to the single rapier machines, only half of the rapier movements are used for filling insertion.

The air jet weaving machines are the weaving machines with the highest weft insertion performance and are considered as the most productive in the manufacturing of light to medium weight fabrics, preferably made of cotton and certain man-made fibers (sheets, shirting fabrics, linings, taffetas and satins in staple yarns of man-made fibers); it has anyway to be pointed out that technically positive results are obtained at present also with heavy weight fabrics (denims) and that some manufacturers produce also machine models for terry production. 

These machines are the ideal solution for those who want to produce bulk quantities of customized fabric styles. The weaving widths range generally from 190 to 400 cm. As regards the multicolor weft carrier, up to 8 different wefts can be fed. It has however to be considered that the air jet weaving machines require a high energy consumption to prepare the compressed air and that this consumption rises definitely with increasing loom width and running speed. The reduction in the energy consumption is in fact one of the main concerns of the manufacturers, and builds for the user an important selection criterion.

Water-Jet Weaving

A water-jet weaving machine inserts the filling yarn by highly pressurized water. The relative velocity between the filling yarn and the water jet provides the attractive force. If there is no velocity difference, then there would be no tension on the yarn results in curling and snarling of the yarn. Water-jet weaving machine can only be used for hydrophobic fibers.