Download - KNITTING Complete

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  • A diversity of constructions, and the variety of fibres and finishes available.

    Generally soft and light weight .

    Good drapability .

    Knitted fabrics conform to the figure without constricting the wearer.

    A high order of wrinkle resistance.

    Creases in knitted fabric brush right out.

    Comfort .

    The knitted structure is porous.

    It allows the skin to breathe freely.

    Its elasticity permits greater freedom of body movements

    Ease of care .

    Knitted apparel launders without difficulty.

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  • Sportswear(conformity, flexibility)

    Casual wear (comfort)

    Dresswear (styling)

    Technical textiles application (medical textile such as hernia mesh, vascular grafts, composite structures, such as nose cones for supersonic aircrafts)

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  • 1. Woven fabrics are constructed by the interlacing of two or more sets of yarns, which does not allow the fabric to stretch to any marked degree unless it is specially stretch -woven . If a certain amount of stretching is necessary, woven fabric must be cut on the bias that is, in a diagonal direction . Even then the fabric can be stretched only in the direction of the diagonal cutting .

    The advantage of stretch ability in knitted fabrics is an important consideration where fit and comfort are concerned they fit the figure but do not bind it .

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  • 2. Knitted fabrics also give warmth because of the insulative air pockets contained in this type of construction .

    Yet they are porous and provide breathing comfort because body movements cause the loops to expand and contract, thus pushing air through close-fitting garments .

    However , unless the fabric is heavily napped or foam laminated, it is not windproof .

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  • 3. Knitted fabrics are very absorbent , light in weight, and wrinkle -resistant .

    4. It is usually unnecessary to iron them after packing and laundering .

    5. However they may shrink considerably more than woven cloth unless special techniques and shrink -proofing processes, such as Pak -nit or permasized are used.

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  • 4. Certain kinds of knitted fabric have one serious disadvantage : if one of the loops breaks , a hole is made, which starts a run .

    This disadvantage can be eliminated by variation in the stitch, which protects the fabric from raveling if any single stitch is broken .

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  • 5. Some knitted fabrics tend to lose their shape and sag.

    This tendency can be avoided by using a more closely constructed knit, giving the yarn a tighter twist, and using such special techniques as the double knit .

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  • 6. Designs can be changed very rapidly in various types of weft knitting .

    Therefore , responses to changes in fashion demands can be made much more quickly than is possible with weaving .

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  • Basic Definitions and Understandings

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  • basic unit of knitted structure.

    consists of a head (H) and two side limbs or legs (L).

    At the base of each leg is a foot (F), which meshes through the head of the loop formed at the previous knitting cycle

    The yarn passes from the foot of one loop into the foot and leg of the next loop formed by it

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  • When one loop is drawn through another, loop stitch is formed.

    The loop is the fundamental element of all knitted fabrics. It is a basic unit consisting of a loop of yarn meshed at its base with previously formed basic units (stitches)

    The stitch is the smallest dimensionally stable unit of all knitted fabrics. It consists of a yarn loop, which is held together by being intermeshed with another stitch or other loops

    Stitch density is the number of stitches per unit area of a knitted fabric (loops / cm 2)

    Stitch length is the length of yarn in a knitted loop

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  • A needle loop is one which has been drawn through a previous loop

    The upper part of the loop produced by the needle drawing the yarn

    A sinker loop is one which connects adjacent needle loops.

    The lower part of the knitted loop is technically referred as sinker loop connection of two legs belonging to the neighboring stitches lying laterally.

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  • Face Loop: During loop formation, when the new loop emerges through the old loop from back to the face (or front) side

    Back Loop: If the new loop passes from the face side to the back side of old loop, it is called as back loop or weft purl loop

    Open Loop: loop forming yarns does not cross at the bottom of the loop.

    Closed Loop: the legs of the loop cross so that the loop closing takes place.

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  • The series of loops that intermesh in a vertical direction are known as 'Wale'. i.e. head to feet direction.

    The loops that are inter -connected widthwise are

    feet to feet direction.

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  • Technically Face

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  • Technically Back

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  • Technically upright

    A knitted fabric is technically upright when its courses run horizontally and its wales run vertically,

    with the heads of the needle loops facing towards the top of the fabric

    and situated at the bottom of the fabric.

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  • Gauge is the term used to describe the needle spacing

    It can be defined as the number of needles per unit length.

    Three chief systems for representing the machine gauge:

    Needles/inch

    Needles/1.5 inch

    Needles/2 inch.

    The gauge is the major factor in determining the fabric density and appearance.

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  • Needles and Loops

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  • Three types of needles

    Latch

    Self acting

    coarser in dimensions

    Expensive

    swinging action of the latch may cause damages to fine filament yarn

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  • Three types of needles

    Spring bearded

    finer in cross section

    requires additional element (presser)

    superior knitted stitches

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  • Three types of needles

    Compound needle

    no yarn strain

    Less movement

    high speed and high productivity

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  • Parts of Needls

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  • Types of Stitches

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  • There are three basic knitted stitches:

    KNIT,

    TUCK and

    MISS (float or non -knit)

    which form the starting point for the entire range of weft knitted structure

    A knitted loop stitch is produced when a needle receives a new loop and knocks over the old loop that it held from the previous knitting cycle. The old loop then becomes a needle loop of normal configuration.

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  • A float stitch or welt 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 reverse side of the resultant stitch, joining together the two nearest needle loops

    knitted from it.

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  • 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 (T) 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.

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  • Loop Formation

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  • The old loop rests on the top of the open latch. Clearing occurs as the held loop slips of the latch and on to the stem as the needle moves upwards.

    A downward movement enables the needle hook to engage a new piece of yarn. This is known as feeding.

    As the needles continue downwards the latch is forced to close under the influence of the held loop.

    Knock over occurs as the held loop disengages from the needle. Following knock over, the loop pulling occurs and a new knit loop is formed.

    Control of the held loop is usually achieved by the use of sinkers or by the application of the fabric tension

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    1. The old loop rests on the top of the open latch. Clearing occurs as the held loop slips of the latch and on to the stem as the needle moves upwards.

    2. A downward movement enables the needle hook to engage a new piece of yarn. This is known as feeding .

    As the needles continue downwards the latch is forced to close under the influence of the held loop.

    3. Knock over occurs as the held loop disengages from the needle. Following knock over, the loop pulling occurs and a new knit loop is formed.

    Control of the held loop is usually achieved by the use of sinkers or by the application of the fabric tension

  • 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/clearing cams.

    Cams controlling the downward movement of the needles are called stitch cams.

    Guard cams keep the needle butts in their race way.

    Running cam up throw cam keep the needle butts at a low level until they meet the next rising cam.

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  • base structures from which all weft knitted fabrics and garments are derived

    Plain

    Rib

    Interlock

    Purl

    Each primary structure may exist alone, in a modified form with stitches other than normal cleared loops, or in combination with another

    primary structure in a garment -length sequence.

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  • Warp knitting differs from weft knitting, basically, in that each needle loops has its own thread .

    The needles produce parallel rows of loops simultaneously that are interlocked in a zigzag pattern

    The stitches on the face of the fabric appear vertically, but at a slight angle ; and the stitches on the back appear horizontally as floats at a slight angle.

    These floats called laps, or under -laps , are a distinguishing identification of warp knits.

    Warp knitting may be flat or tubular and can be produced in many varieties of patterns.

    It can yield cloth with a dimensional stability almost equal to woven fabrics .

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