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    Sunday 4 March 2012

    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.

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

    Posted at  21:27  |  in  regular  |  Continue lendo ...»

    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.

    0 comments:

    There are certain technical tests performedfor identifying various fibers. These tests require high technology laboratory equipment and are much more reliable than the non technical fibre tests.Technicals tests require high skilled personnel and technical know how of handling chemicals and their accurate analysis. These tests are very valuable for those fabrics that are a blend of different yarns and also have certain special properties including flame retardance etc.  

    TYPES OF TECHNICAL TEST
    1.  Microscopic test 
    2. Chemical test
    MICROSCOPIC TEST 
    1.  Microscopic test is a technical test that involves identifying the fabric with the help of a microscope with a magnification of minimum 100 power.
    2.  The test can easily distinguish between fibers.
    3. The test identifies the natural fibers more easily as compared to man made ones.
    4. Synthetic fibers are very similar in appearance and the increase in the number of varieties, makes it a little tough to distinguish the fibers even under a microscope.
    MICROSCOPIC TEST FOR NATURAL FIBERS

    COTTON:

    • It is a single elongated cell. Under the microscope, it resembles a collapsed, spirally twisted tube with a rough surface.
    •  The thin cell wall of the fiber has from 200 to 400 convolutions per inch.
    LINEN:
    • Under the microscope, the hair like flax fiber shows several sided cylindrical filaments with fine pointed ends.
    •  The fiber somewhat resembles a straight, smooth
    WOOL:

    • Under the microscope , wool’s cross section shows three layers- epidermis, cortex and the medulla.
    SILK:
    • It appears somewhat elliptical and triangular in cross section when we see under the microscope.
    • It is composed of fibroin, consisting of two filaments, called brin which is held together by sericin.
    MICROSCOPIC TEST FOR MANMADE FIBERS

    RAYONS:

    • Rayon fibers have a glasslike luster under the microscope and appear to have a uniform diameter when viewed longitudinally.
    ACETATE:
    •  The cross sectional view has a bulbous or multilobal appearance with indentations.
    •  These indentations appear as occasional markings or
    NYLON:

    •  The basic microscopic appearance is generally fine ,round, smooth, andtranslucent.
    •  It is also produced in multilobal cross-sectional types.
    POLYESTERS:
    •  Generally, polyester fibers are smooth and straight and the cross-section is round.
    •  This general characteristics may be altered to achieve certain characteristics, such
    ACRYLICS: The methods of manufacturing of the acrylic fibres differ, the appearances vary accordingly.
    •  ACRILAN ACRYLIC: It has a bean-shaped cross section, its longitudinal appearance is straight and smooth.
    •  ORLON ACRYLIC: It has a flat, nut-shaped cross section.
    •  CRESLAN ACRYLIC: It has an almost round cross section.
    •  MOD ACRYLICS: it is of two types verel modacrylic and SEF modacrylic
    SPANDEX: Spandex fibers are unique in appearance, they appear to be groups of fibersfused together.

    GLASS:
    The fiber is smooth, round, translucent, highly lustrous, and quite flexible.

    CHEMICAL TESTS

    •  Chemical tests are another technical means of identifying fibers. But chemical tests are not intended for the general consumers.
    •  Different types of chemical tests are undertaken to establish the identity of the fibers used.
    •  These tests give accurate and precise analysis.
    •  The tests are conducted in research laboratories.
    TYPES OF CHEMICAL TEST

    Stain Test:
    Also known as the Double Barrel Fibre Identification (DBFI), the test is based on the theory that each fibre has its own distinct two- colour reaction when treated with stain.

    A fibre will turn to a particular colour in the presence of dilute acetic acid and to some other specific colour when stained in the presence of a mild alkali.

    Solvent Test:
    The test involves treating the fibres in certain solvents for identifying them. The technical test is becoming difficult to conduct as most of the manufactured fibres and their blends are chemically similar. There is no individual chemical or solvent test for separating or identifying the fibres in combinations

    This technical fibre identification test has the following
    advantages and limitations

    Advantages
    • More reliable than the non technical tests.
    • Used for both man made fibres and natural fibres.
    • Easily conducted.

    Limitations
    • Certain manufacturing and finishing processes like mercerizing, affects the appearance of the fibres under the microscope.
    • Very dark coloured fabrics cannot be identified under microscope.
    • Dye stuffs must be removed from fabrics.

    Microscopic Test for Natural Fiber | Microscopic Test for Manmade Fiber| Chemical Test for Textile Fiber

    Posted at  17:39  |  in  TTQC  |  Continue lendo ...»

    There are certain technical tests performedfor identifying various fibers. These tests require high technology laboratory equipment and are much more reliable than the non technical fibre tests.Technicals tests require high skilled personnel and technical know how of handling chemicals and their accurate analysis. These tests are very valuable for those fabrics that are a blend of different yarns and also have certain special properties including flame retardance etc.  

    TYPES OF TECHNICAL TEST
    1.  Microscopic test 
    2. Chemical test
    MICROSCOPIC TEST 
    1.  Microscopic test is a technical test that involves identifying the fabric with the help of a microscope with a magnification of minimum 100 power.
    2.  The test can easily distinguish between fibers.
    3. The test identifies the natural fibers more easily as compared to man made ones.
    4. Synthetic fibers are very similar in appearance and the increase in the number of varieties, makes it a little tough to distinguish the fibers even under a microscope.
    MICROSCOPIC TEST FOR NATURAL FIBERS

    COTTON:

    • It is a single elongated cell. Under the microscope, it resembles a collapsed, spirally twisted tube with a rough surface.
    •  The thin cell wall of the fiber has from 200 to 400 convolutions per inch.
    LINEN:
    • Under the microscope, the hair like flax fiber shows several sided cylindrical filaments with fine pointed ends.
    •  The fiber somewhat resembles a straight, smooth
    WOOL:

    • Under the microscope , wool’s cross section shows three layers- epidermis, cortex and the medulla.
    SILK:
    • It appears somewhat elliptical and triangular in cross section when we see under the microscope.
    • It is composed of fibroin, consisting of two filaments, called brin which is held together by sericin.
    MICROSCOPIC TEST FOR MANMADE FIBERS

    RAYONS:

    • Rayon fibers have a glasslike luster under the microscope and appear to have a uniform diameter when viewed longitudinally.
    ACETATE:
    •  The cross sectional view has a bulbous or multilobal appearance with indentations.
    •  These indentations appear as occasional markings or
    NYLON:

    •  The basic microscopic appearance is generally fine ,round, smooth, andtranslucent.
    •  It is also produced in multilobal cross-sectional types.
    POLYESTERS:
    •  Generally, polyester fibers are smooth and straight and the cross-section is round.
    •  This general characteristics may be altered to achieve certain characteristics, such
    ACRYLICS: The methods of manufacturing of the acrylic fibres differ, the appearances vary accordingly.
    •  ACRILAN ACRYLIC: It has a bean-shaped cross section, its longitudinal appearance is straight and smooth.
    •  ORLON ACRYLIC: It has a flat, nut-shaped cross section.
    •  CRESLAN ACRYLIC: It has an almost round cross section.
    •  MOD ACRYLICS: it is of two types verel modacrylic and SEF modacrylic
    SPANDEX: Spandex fibers are unique in appearance, they appear to be groups of fibersfused together.

    GLASS:
    The fiber is smooth, round, translucent, highly lustrous, and quite flexible.

    CHEMICAL TESTS

    •  Chemical tests are another technical means of identifying fibers. But chemical tests are not intended for the general consumers.
    •  Different types of chemical tests are undertaken to establish the identity of the fibers used.
    •  These tests give accurate and precise analysis.
    •  The tests are conducted in research laboratories.
    TYPES OF CHEMICAL TEST

    Stain Test:
    Also known as the Double Barrel Fibre Identification (DBFI), the test is based on the theory that each fibre has its own distinct two- colour reaction when treated with stain.

    A fibre will turn to a particular colour in the presence of dilute acetic acid and to some other specific colour when stained in the presence of a mild alkali.

    Solvent Test:
    The test involves treating the fibres in certain solvents for identifying them. The technical test is becoming difficult to conduct as most of the manufactured fibres and their blends are chemically similar. There is no individual chemical or solvent test for separating or identifying the fibres in combinations

    This technical fibre identification test has the following
    advantages and limitations

    Advantages
    • More reliable than the non technical tests.
    • Used for both man made fibres and natural fibres.
    • Easily conducted.

    Limitations
    • Certain manufacturing and finishing processes like mercerizing, affects the appearance of the fibres under the microscope.
    • Very dark coloured fabrics cannot be identified under microscope.
    • Dye stuffs must be removed from fabrics.

    0 comments:

    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

    Introduction of Knitting Machines | Classification of Knitting Machines

    Posted at  13:48  |  in  regular  |  Continue lendo ...»

    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

    0 comments:

    Experiment name: Analysis of woven fabric. (Sateen)

    Object:
    1. To know about the structure of fabric.
    2. To know about the raw material of fabric.
    3. To produce exactly the similar fabric.

    Sample: 

    Apparatus:
    1. Counting glass,
    2. Needle,
    3. Beesleys balance,
    4. Twist tester,
    5. GSM cutter,
    6. Graph paper.

    Analysis Sateen Fabric: 


    1. Weave plan: In graph the gaps between the lines are considered according to X axis as weft  threads and according to Y axis as warp threads. The up threads are indicated by filling up the gaps and down threads without filling up the gaps.

    2. Drafting plan: According to British system drafting plan is drawn at the top of weave plan. Here broken draft is used to draft the plan.

    3. Lifting plan: The lifting plan is drawn at the right side of the weave plan.

    4. Face side and backside: The face side and back side are not same.

    5. Direction of warp and weft: Direction of both warp and weft are indicated by arrow marks by the side of the sample.

    6. Raw material: Both warp and weft yarns are filament. 


    7. Thread density:
    No. of reading
    EPI
    Average
    PPI
    Average
    1
    44
    45
    42
    41
    2
    45
    39
    3
    46
    40
    4
    43
    43
    5
    47
    41

    8. Yarn count:
    No. of reading
    Warp count
    Average
    Weft count
    Average
    1
    20


    21
    19


    21
    2
    22
    23
    3
    23
    20
    4
    21
    22
    5
    19
    21

    9. Yarn twist:
    No. of reading
    Warp twist
    Average
    Weft twist
    Average
    1
    X


    X
    X


    X
    2
    X
    X
    3
    X
    X
    4
    X
    X
    5
    X
    X

    10. Direction of twist: As the yarns are filament so they have no twist.

    11. Design of fabric: As it is a derivative of twill so it has no formula number.

    12. GSM calculation: By GSM cutter we get the GSM of fabric is 130 gm/meter2.

    13. Repeat size: The repeat size of this fabric is 24X24.

    14. Type of loom: Dobby loom is used to produce this fabric.

    End Use: This type of fabric is very much used for making towel, bed sheet, pillow, table cloth etc.

    Conclusion: 
    Analysis of fabric structure is very essential to know about the fabric. Because it gives all kinds of information about the fabric that is needed to reproduce or to change structure or design of fabric. By this practical I learn how to analyse primarily a simple plain structure of woven fabric. Further I will learn more complex fabric analysis. But this basic structure analysis will be very much helpful not only to analyse those but also in my future career.

    Analysis of Fabric | Analysis of Sateen Woven Fabric Stracture

    Posted at  02:36  |  in  regular  |  Continue lendo ...»

    Experiment name: Analysis of woven fabric. (Sateen)

    Object:
    1. To know about the structure of fabric.
    2. To know about the raw material of fabric.
    3. To produce exactly the similar fabric.

    Sample: 

    Apparatus:
    1. Counting glass,
    2. Needle,
    3. Beesleys balance,
    4. Twist tester,
    5. GSM cutter,
    6. Graph paper.

    Analysis Sateen Fabric: 


    1. Weave plan: In graph the gaps between the lines are considered according to X axis as weft  threads and according to Y axis as warp threads. The up threads are indicated by filling up the gaps and down threads without filling up the gaps.

    2. Drafting plan: According to British system drafting plan is drawn at the top of weave plan. Here broken draft is used to draft the plan.

    3. Lifting plan: The lifting plan is drawn at the right side of the weave plan.

    4. Face side and backside: The face side and back side are not same.

    5. Direction of warp and weft: Direction of both warp and weft are indicated by arrow marks by the side of the sample.

    6. Raw material: Both warp and weft yarns are filament. 


    7. Thread density:
    No. of reading
    EPI
    Average
    PPI
    Average
    1
    44
    45
    42
    41
    2
    45
    39
    3
    46
    40
    4
    43
    43
    5
    47
    41

    8. Yarn count:
    No. of reading
    Warp count
    Average
    Weft count
    Average
    1
    20


    21
    19


    21
    2
    22
    23
    3
    23
    20
    4
    21
    22
    5
    19
    21

    9. Yarn twist:
    No. of reading
    Warp twist
    Average
    Weft twist
    Average
    1
    X


    X
    X


    X
    2
    X
    X
    3
    X
    X
    4
    X
    X
    5
    X
    X

    10. Direction of twist: As the yarns are filament so they have no twist.

    11. Design of fabric: As it is a derivative of twill so it has no formula number.

    12. GSM calculation: By GSM cutter we get the GSM of fabric is 130 gm/meter2.

    13. Repeat size: The repeat size of this fabric is 24X24.

    14. Type of loom: Dobby loom is used to produce this fabric.

    End Use: This type of fabric is very much used for making towel, bed sheet, pillow, table cloth etc.

    Conclusion: 
    Analysis of fabric structure is very essential to know about the fabric. Because it gives all kinds of information about the fabric that is needed to reproduce or to change structure or design of fabric. By this practical I learn how to analyse primarily a simple plain structure of woven fabric. Further I will learn more complex fabric analysis. But this basic structure analysis will be very much helpful not only to analyse those but also in my future career.

    0 comments:

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