Introduction of a Needle | Specifications of Needle

The typical “European” specifications for a needle includes a word, a number (usually a four digit number) and a final combination of letters and numbers. For example: Vota 78.60 G.02 The capital letter at the beginning of the word ( “V”), identifies the origin of the needle (obtained from a wire, pressed or die-cut), the type, the number of butts and the type of tail. The other capital letters have a very precise meaning, except for the vowels “e” and “a” which are added to make the word pronounceable, and indicate the shape and the height of the butt, the eventual existence of a groove and its size, the length of the tail and some other features of the

needle.

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The next group of numbers identifies the needle according to the length and the gauge. The first part indicates the whole length rounded off to the mm (in our case that makes 78 mm); the second part indicates the gauge of the needle in hundredths of millimetres (in our case the gauge of the needle is equal to 0.60 mm).

The final group of letters and numbers has to be read as follows. The first capital letter indicates the needle manufacturer (For example Z for Torrington, E for Exeltor, G for Groz-Beckert). The next number is used to distinguish a specific needle among all the needles produced by the same manufacturer.

The next letter refers to some particular features of the needle: for some needles an “A” indicates that the latch has been fixed with an angular pressed pin while an “R” means that the latch has been fixed with a straight pressed pin. For other needles, the latch fixing method is indicated by a “0” before the last number. A “0” indicates that the latch has been fixed with a standard pressed pin; no “0” means that the latch has been fixed with a screw pin.

Crochet Machine | Knitting Elements of a Crochet Machine

The Crochet Machine
In hand crocheting, a hook is used to draw a new loop through the old loop with the chains of loops being joined together at intervals. On crochet machines, the warp chains are separate from the weft inlay and it is the latter threads that join the chaining wales to each other. 

Knitting Elements of a Crochet Machine

• 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 sideways crimped beard placed in a permanently-pressed position. Although warp threads can only be fed into the beard from the left (necessitating a unidirec-tional closed overlap), the old overlaps are automatically cleared and landed by the movement of the needle. It is still the most frequently used needle, achieving speeds up to 2500 rpm. Reduced machine speed and high needle wear make its use uneconomical for knitting single end cotton yarns.

• No sinkers; instead a fixed hold-back bar is fitted in front of the knock-over verge to prevent the fabric moving out with the needles. 

Knitting Elements of a Crochet Machine

• Closed lap pillar stitches and inlay threads controlled and supplied as separate warp and weft respectively. Each needle is lapped from below by its own warp guide, which is clipped to a bar whose automatic one-needle overlap and return and underlap shog is fixed and is controlled from an eccentric cam whilst its upwards and downwards swing is derived from a rocker-shaft. The warp yarn is often placed low at the front of the machine. 

• The weft yarn, often placed above and towards the back of the machine, supplying the carrier tubes, which are clipped to the spring-loaded inlay bars.These bars are fitted above the needle bar and are shogged at the rate of one link per course, from pattern chains around a drum at one end of the machine.There are usually up to two warp guide bars and up to 16 weft inlay bars, which may be electronically controlled.

• Special attachments are available for producing fancy effects such as cut or uncut fringe edges, pile, braiding (equivalent to fall-plate) and snail shell designs.

Crochet machines, with their simple construction, ease of pattern and width changing, and use of individual yarn packages or beams provide the opportunity for short runs on coarse- or fine-gauge fancy and open-work structures and edgings, as well as the specialist production of wide fancy fabrics or narrow elastic laces.

Knitting Action of the Compound Needle Warp Knitting Machine | KnittingAction of the Compound Needle Tricot Machine

Needle rise and guide bar swing: 

With the sinkers forward holding down the fabric, the hooks and tongues rise, with the hook rising faster, until the head of the latter is level with the guide holes and is open.The guides then swing through to the back of the machine.

2. The overlap and return swing:
The guides shog for the overlap and swing to the front of the machine; immediately, the hooks and the tongues start to descend with the tongues descending more slowly, thus closing the hooks.

Fig.  Knitting action of a compound needle tricot machine

3. Landing and knock-over:
The sinkers start to withdraw as the needles descend so that the old loop is landed onto the closed hook and then knocked-over as it descends below the sinker belly. At this point the underlap occurs before the needles begin their upward rise and the sinkers move forward to hold down the fabric.

The Karl Mayer tricot model HKS 2–3 E is designed to knit elastic fabrics and has a maximum speed of 3300 cpm with reduced noise levels and energy consumption.The vertical staggered arrangement of the guide bars enables the stroke to be reduced.The bars are hollow section which reduces their weight and expansion due to heat.

Features of the Latch Needle

Latch Needle

Fact and fiction envelopes the invention of the latch needle in a similar manner to that of the bearded needle. Pierre Jeandeau patented the first latch needle (also known as the tumbler needle) in 1806 but there is no evidence of its practical use.There is also no evidence that the pivoting of a broken pocket knife blade led to the development of the latch spoon.

The latch needle has nine main features (Fig. A):

1 The hook, which draws and retains the new loop.

2 The slot or saw cut, which receives the latch-blade (not illustrated).

3 The cheeks or slot walls, which are either punched or riveted to fulcrum the latch blade (not illustrated).

4 The rivet, which may be plain or threaded.This has been dispensed with on most plate metal needles, by pinching in the slot walls to retain the latch blade.

5 The latch-blade, which locates the latch in the needle.

6 The latch spoon, which is an extension of the blade, and bridges the gap between the hook and the stem covering the hook when closed, as shown in broken lines.

7 The stem, which carries the loop in the clearing or rest position.

8 The butt, which enables the needle to be reciprocated when contacted by cam profiles on either side of it, forming a track. Double-ended purl type needles have a hook at each end; whilst one hook knits, the inactive hook is controlled as a butt by a cam-reciprocated element called a slider.

9 The tail, which is an extension below the butt, giving additional support to the needle and keeping the needle in its trick.

Fig.A. Main features of the latch needle.

Introduction of Under Lap | Closed Lap | Open Lap

The Under Lap

The underlap shog occurs across the side of the needles remote from the hooks on the front of single-needle bar, and in the centre of double-needle bar, warp knitting machines. It supplies the warp yarn between one overlap and the next (Fig.A).The underlap shog generally ranges from 0 to 3 needle spaces, but it might be 14 needle spaces or more depending upon the design of the machine and the fabric structure (although efficiency and production speed will be correspondingly reduced with long underlaps).

A.Under lap shog

Underlaps as well as overlaps are essential in warp knitted structures in order to join the wales of loops together but they may be contributed by different guide bars.

The Closed Lap
A closed lap is produced when a subsequent underlap shogs in the opposite direction to the preceding overlap, thus lapping the same yarn around the back as well as around the front of the needle (Fig.B).

B.Closed Lap

The Open Lap
An open lap is produced either when a subsequent underlap is in the same direction as the preceding overlap (Fig.C) or an underlap is omitted so that the overlap of the next knitting cycle commences in the needle space where the previous overlap finished. Closed laps are heavier, more compact, more opaque, and less extensible than open laps produced from the same yarn at a comparable knitting quality. 

C.Open Lap

Main Parts of the Bearded Needle

The Main Parts of the Bearded Needle

There are five main parts of the bearded needle (Fig:A):

1 The stem, around which the needle loop is formed.

2 The head, where the stem is turned into a hook to draw the new loop through the old loop.

3 The beard, which is the curved downwards continuation of the hook that is used to separate the trapped new loop inside from the old loop as it slides off the needle beard.

4 The eye, or groove, cut in the stem to receive the pointed tip of the beard when it is pressed, thus enclosing the new loop.

5 The shank, which may be bent for individual location in the machine or cast with others in a metal ‘lead’.

  Fig. A:  Main parts of the bearded needle.

What is Float Stitch/Tuck Stitch? | Successive Tucks and Floats on theSame Rib Needle

Float Stitch

A float stitch or welt stitch (Fig.A) is composed of a held loop, one or more float loops and knitted loops. It is produced when a needle (M) 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 reverse side of the resultant stitch, joining together the two nearest needle loops knitted from it.

Fig.A

In Fig.B, the float stitch shows the missed yarn floating freely on the reverse side of the held loop. (This is the technical back of single-jersey structures but is the inside of rib and interlock structures.) The float extends from the base of one knitted or tucked loop to the next, and is notated either as an empty square or as a bypassed point. It is assumed that the held loop extends into the courses above until a knitted loop is indicated in that wale.

Fig.B

A single float stitch has the appearance of a U-shape on the reverse of the stitch. Structures incorporating float stitches tend to exhibit faint horizontal lines. Float stitch fabrics are narrower than equivalent all-knit fabrics because the wales are drawn closer together by the floats, thus reducing width-wise elasticity and improving fabric stability.

The 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 but is tucked in behind it on the reverse side of the stitch(Fig.C). Its side limbs are therefore not restricted at their feet by the head of an old loop, so they can open outwards towards the two adjoining needle loops formed in the same course. The tuck loop thus assumes an inverted V or U-shaped configuration. The yarn passes from the sinker loops to the head that is intermeshed with the new loop of a course above it, so that the head of the tuck is on the reverse of the stitch.

Fig.C

The tuck loop configuration can be produced by two different knitting sequences:

1 By commencing knitting on a previously empty needle. As the needle was previously empty, there will be no loop in the wale to restrict the feet of the first loop to be knitted and, in fact, even the second loop tends to be wider than normal. The effect is clearly visible in the starting course of a welt. By introducing rib needles on a selective basis, an open-work pattern may be produced on a plain knit base.

2 By holding the old loop and then accumulating one or more new loops in the needle hook. Each new loop becomes a tuck loop as it and the held loop are knocked-over together at a later knitting cycle and a new loop is intermeshed with them. This is the standard method of producing a tuck stitch in weft knitting.

Successive Tucks and Floats on the Same Rib Needle

Successive tucks on the same needle are placed on top of each other at the back of the head of the held loop and each, in turn, assumes a straighter and more horizontal appearance and theoretically requires less yarn. Under normal conditions, up to four successive tucks can be accumulated before tension causes yarn rupture or needle damage. The limit is affected by machine design, needle hook size, yarn count, elasticity and fabric take-down tension (Fig.D). 

Fig.D :Successive tucks and floats on the same rib needle.

Introduction of Knitting Machines | Classification of Knitting Machines

The machines used for the manufacturing of knit fabrics can be divided into machines with individually driven needles and needle bar machines. The former type of machine incorporates needles which are moved individually by cams acting on the needle butt; they are used for producing weft knits and are subdivided into circular knitting machines and flat-bed knitting machines.

The needles used can be latch needles or compound needles. The needle bar machines incorporate needles which move simultaneously, since they are all fixed to the same bar; we distinguish full-fashioned knitting machines and circular loop-wheel machines for the production of weft knit fabrics, which only use spring-beard needles, and warp knitting machines which use spring-beard needles, latch needles and compound needles.

Classification of Knitting Machines

Basic Knitting Action of a Needle

The basic action of a needle are shown in below. Except for the manner in which the hook is closed (in this case by pressing the beard), the knitting action is similar for all needles.The arrows indicate the relative movement of the loops along the needles. (Whether the needle moves through the loops or the loops are moved over the needle by some other elements depends upon the machine design.)

1. The needle is in the (so-called) rest position, with the previously formed loop (a) held on its stem and covered by the hook.

2. The loop is cleared from the needle hook to a lower position on the needle stem.

3. The new yarn (b) is fed to the needle hook at a higher position on the needle stem than the position of the previous (‘old’) loop.

4. The yarn is formed into a ‘new’ loop.

5. The hook is closed, enclosing the new loop and excluding and landing the old loop onto the outside of the closed hook.

6. The new loop (b) is drawn through the head of the old loop (a). Simultaneously the old loop slides off the closed hook of the needle and is cast-off or knocked-over.

7. The old loop now hangs from the feet of the fully formed new loop and the knitting cycle starts again.

Fig. Basic knitting action of a needle.