Presentation on theme: "Sinker: Sinker is a thin metal plate which placed in the middle position of each two needle. These sinkers are parrallely attached in 1″ lead. Sinker acts."— Presentation transcript:
1 Sinker:Sinker is a thin metal plate which placed in the middle position of each two needle. These sinkers are parrallely attached in 1″ lead. Sinker acts in holding down, knocking over and supporting the fabric. When the needle is moved downwards then sinker throat holds down the fabric and belly knocks over.Guides and guide bar:Guides are mounted on guide bar. The threads are passed into the guides of the guide bar. Guide bar gets shogging and swinging movements from main shaft and pattern chain.0,1, 2, 3, or 4 guide bars are used in tricot m/c. tricot m/c with two guide bat are mostly used but tricot m/c with more number of guide bar are less used.
2 FeatureRachel warp knitting m/c: 1. Rachel m/cs used latch needles together with a wire or blade2. It has a gauge expressed in needles per 2inches (5cm) so that for example a 36 gauge Rachel m/c will have 18npi3. Their chain links are usually numbered in even numbers 0, 2, 4, ….etc generally with 2 links/course4. Rachel sinkers only performs the function of holding down the loops whilst the needles rise5. Rachel sinkers are not joined together by a lead across their ends nearest to the needle bars so they can move away clear of the needles towards the back of the m/c for the rest of the knitting cycle6. The fabric is drawn downwards from the needles, almost parallel to the needle bar at an angle of 120°-160° by a series of take-down rollers.
3 7. The warp beams are arranged above the needle bar, centered over the rocker shaft, so that the warp sheets pass down to the guide bars on either side of it8. The beams are placed above the m/cs so that it is accessible at the front for the fabric inspection9. At least four 32″ diameter beams or large numbers of small diameter pattern bars10. The guide bars are threaded, connecting with the middle bars and working outwards from the eitherside of the rockershaft11. The guide bars are numbered from the front of the m/c12. The needle trick plate acts as a fabric support ledge and knockover surface.
5 Knitting elements of Rachel m/c: Needle:Most of the modern Rachel knitting m/cs built today use compound needle. Many m/cs, however, are still equipped with latch needles. Compound needles are set as in Tricot m/cs into trick which are cut into the needle bar and both main parts and closing elements are driven separately to open and close the hook.Trick plate:The loop formation in a Rachel m/c takes place on the upper edge of the trick plate. This bar can be considered as a needle bed, since the needles are placed in tricks cut into it.
6 The sinker:The sinker like the latch needles are cust in units 1″ long placed in the spaces between the needles. They are used to ensure that the fabric stays bowl while the needle rise to form their next knitting cycles. The sinker of Rachel m/cs are therefore only of secondary importance
7 The latch guard:A steel wire which are extended from one ends to the others parallel to the needle. During loop formation, the fabric loops open needle latch but sometimes closed the needle hook. As a result a closed hook cannot feed the new yarn. This latch guard placed needle hook side. So that the latch cannot close the hook and helps to open the needle hook.Guide & Guide bar:The number of guide bar in Rachel m/c is more. Sometimes are of more than 70. Two types of guide bar are used-Fully threaded guide bar: Used to produce ground fabric and yarn pass to each guide.Partially threaded guide bar: According to the design. One yarn is passed in each bar for each pattern repeat. Thread pass where design placed.
8 Difference between Tricot & Rachel warp knitting m/c: Tricot Raschel In the past, bearded needle was used but now a days compound needle usedM/C gauge expressed in needle per inchChain link numbering 0, 1, 2, 3, ….etcFunction of sinker is holding down, knocking and supporting the fabricThe fabric is drawn away towards the batching roller almost at right angles to the needle barThe warp beams are accommodated in an inclined towards the back of the m/c there the topThe warp sheets pass over the top of the guide bar rockershaft to their tensionMechanical attention is carried out at the front of the m/cThe guide bars are numbered from the back towards the front of the m/cHigh speed productionRachel m/c used latch needle together with a wire or bladeM/C gauge expressed in needle/2inchChain link numbered in even numbers 0, 2, 4, ….etcSinker performs the function of holding down the loops whilst the needle riseThe fabric is drawn downwards from the needles almost parallel to the bar at an angle of 120°-160°The warp beams are arranged above the needle bar centered over the rocker shaftThe warp sheets pass down the guide barMechanical attention is carried out at the back of the m/cThe guide bars are numbered from front of the m/cLow speed productionMd.Ahashan Habib B.Sc in Textile Engr.(DU) Lecturer:Daffodil International University
10 Features The crochert warp knitting m/c: A single horizontal needle bar whose simple reciprocating action can be used to operate individually – tricked latch, carbine or embroidery needles. The patent or carbine bearded needle is used for fine structures and has a side ways crimped beard placed in a permanently-pressed position. Although warp threads can only be fed into the beard from the left, the old overlaps are automatically cleared and landed by the movement of the needle. The needles can be arranged for coarser gauges or for fancy set-outs, when the floating inlay threads may be cut to produce separated fringed edgings.2. No sinkers; instead a fixed hold back bar is fitted in from of the knock over verge to prevent the fabric moving out with the needles3. The closed lap pillar stitches and inlay threads controlled and supplied as separate warp and weft respectively
11 4. The weft yarn, often placed above and towards the back of the m/c, supplying the carrier tubes which are clipped to the spring loaded inlay bars.5. Special arrangements/attachments are available for producing fancy effects such as cut or uncut fringe edges, pile, braiding and snail shell designs.6. Gauge often expressed in needles per centimeter are between 2 and 10 (E5 to E24)7. Knitting widths of crochet m/cs may vary between 16 and 122 inches.8. M/C runs at speeds between 200 and 350 courses per minute9. Crochet m/cs can process a range of filament yarn from 20dtex to 1000dtex10. The warp yarn is often placed low at the front of the m/c.
15 WEFT KNITTING Types of weft knitting m/c: According to the end product, the weft knitting m/c may be broadly classified as either:Fabric m/csGarment length m/csAccording to their frame design and needle bed arrangement, the weft knitting m/c may be broadly classified as either:Straight bar frame m/csFlat knitting m/csCircular knitting m/cs
16 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 efficiencySinker 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
17 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 fabricsThe 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
18 Flat knitting m/c: Feature: 2 stationary needle bed in flat knitting m/c arranged in an inverted V formationLatch needle is usedAngular cam of a bi-directional cam system usedThere is a separate cam system for each needle bedThe two cam systems linked together by a bridge, which passes across from one needle bed to the otherCarriage with determined yarn carrier issuedCam system is attached to bottom side of carriageThe flat m/c is the most versatile of the weft knitting m/cFabric produce with finer to coarser yarnThe operation and supervision of the m/c is simpleThe stitch length range is wide and possibly of changing the m/c gaugeTrimmings, edging, collars, to shaped panels and integrally knitted complex garments and other articles
19 Classification of circular knitting m/c: 1. Circular bearded needle single-jersey fabric machine2. Revolving cylinder latch needle machine3. Circular garment length machine1. Circular bearded needle single jersey fabric machine:Types of machines are divided into two types:-a) Sinker wheel machine or French/Terrot type m/cb) Loop wheel frame or English type m/cBoth of them have the following common features:-Needles are fixed in a revolving circle on needle bedKnitting action is entirely achieved by ancillary elements moving yarn and loops along the needle stemHere tubular fabric is knitted with its technical back facing outwardLow productivity but has an ability to produce unusual and super-quality knitted structures2. 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/cCylinder & dial m/c or double-jersey mc/
20 Knitted Loop Knit Loop Tuck Loop Miss Loop Md.Ahashan Habib B.Sc in Textile Engineering(DU)4/13/2017
21 Tuck stitch:A tuck stitch is composed of a held loop, one or more tuck loops and knitted loops.It is produced when a needle holding its loop also receives the new loop which becomes a tuck loop, because it is not intermeshed through the old loop.Miss/Float stitch:A float stitch is composed of a held loop, one or more float loops and knitted loops. It is produced when a needle holding its old loop fails to receive the new yarn that passes, as a float loop, to the back of the needle and to the reveres side of the resultant stitch.The miss stitch can occur accidentally as a fault due to incorrectly set yarn feeders.
22 Methods to obtain Tuck/Held loops: 1. Without casting off operation in loop forming cycle , i.e. Tucking of the latch2. Without clearing operation in loop forming cycle, i.e. Tucking in the hook3. With switching a needle out of action from loop forming cycleTucking on the latch:When tuck stitch formation is performed without casting-off and sinking are excluded from the loop formation cycle. In this case, the needles 4 and 7 knit the loops 3 and 6, while the needle 5 performs all the operations up to joining and stops. Then a new yarn 2 is fed in its hook and this will be the tuck loop, the old loop 1 remains on the closed latch and this will be the held loop.After the needle 5 is lifted for clearing, in the following loop formation cycle it receives a new yarn and knits a loop from it, casting-off upon it old held loop 1 and the tuck loop 2Step of forming held loop in 5 needle:
25 Difference between Warp knitting & Weft knitting Difference between Warp knitting & Weft knitting. Warp Knitting Weft KnittingThe loops are produced to the length of fabricThe threads runs in the vertical directionEach loop in the horizontal direction is made from a different threadIt is elastic to the lengthIt’s elasticity is lessYarns are supplied from beamAt least one yarn is needed for each needleLess shrinkageThe loops are produced to the width of the fabricThe threads runs in the horizontal directionA horizontal row of loops can be made by using on threadIt is elastic to the widthHigher elasticityFrom coneAny number of needle are required for on e yarnMore/Higher shrinkage