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Introduction to Textile Introduction to Textile Fabric Fabric Part 1: Basic Knitted Fabrics Part 1: Basic Knitted Fabrics Introduction to Textile Introduction to Textile Fabric Fabric Part 1: Basic Knitted Fabrics Part 1: Basic Knitted Fabrics Dr. Jimmy Lam Dr. Jimmy Lam Institute of Textiles & Clothing Institute of Textiles & Clothing The Hong Kong Polytechnic University The Hong Kong Polytechnic University

Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

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Page 1: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

Introduction to Textile Introduction to Textile FabricFabric

Part 1: Basic Knitted FabricsPart 1: Basic Knitted Fabrics

Introduction to Textile Introduction to Textile FabricFabric

Part 1: Basic Knitted FabricsPart 1: Basic Knitted FabricsDr. Jimmy LamDr. Jimmy Lam

Institute of Textiles & ClothingInstitute of Textiles & ClothingThe Hong Kong Polytechnic UniversityThe Hong Kong Polytechnic University

Page 2: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

Content• Difference between woven and knitted fabric

• Single Knit Fabric– Properties and Characteristics

– Knitting Notation

• Basic loop (knit, tuck and miss)

Page 3: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

Difference between woven and knitted fabrics

• 1) Fabric Construction– Woven fabric is at least made

up of two separate groups of yarns (warp and weft) and knitted fabric can be made up of one yarn only.

– Weaving is interlacing of 2 set of yarn to form a fabric.

– Knitting is a process of converting yarn to fabric by forming a series of loops dependent on each other.

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Difference between woven and knitted fabrics

• 2) Elasticity

– Elasticity is the ability of the fabric to extend and recover to its original shape and length.

– Knitted fabric has higher extensibility and instant recovery ability than woven fabric. up of one yarn only.

Page 5: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

Difference between woven and knitted fabrics

• 3) Fabric Density and Cover

– In general, woven fabric can be produced in extremely tight and higher coverage when compared with knitted fabric.

– Range of density variation is much higher than knitted fabric.

– Knitted fabric in general, is looser in structure.

Page 6: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

Difference between woven and knitted fabrics

• 4) Thickness and Handle

– Knitted fabric is much thicker and softer than woven fabric as it has a complicated 3-dimensional structure.

– Knitted fabric seems to be softer because the knitted loops are more easily compress and extensible than straight yarn (warp and weft in woven fabric)

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Difference between woven and knitted fabrics

• 5) Production Cost

– Weaving requires expensive preparation processes like warping, sizing, draw-in; while knitting only requires yarn waxing.

– The production rate of circular knitting is roughly FIVE times faster than modern weaving loom. and weft in woven fabric)

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Difference between woven and knitted fabrics

• 6) Fabric Application

– The popularity of sportswear, hosiery, underwear and high fashion knitwear make a strong demand on knitted fabric every year which cannot be replaced by woven fabric.

– However, if fabric requires good dimensional stability, high tenacity like trousers, jackets, canvas, woven fabric is the right choice

Page 9: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

Single Knit FabricSingle Knit FabricSingle Knit FabricSingle Knit Fabric

Page 10: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

What is single knit fabric• Single knit fabric or single jersey is a

general term for knitted fabrics produced by the knitting machines using one set of needles only.

• The fabrics could be composed of different patterns, stitches, materials and different weight and thickness.

Page 11: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

General Characteristics of Single Knit Fabric

1) Fabric Elasticity• The single knit fabrics are composed of loops linking

with each other on the two sides as well as on the two ends.

• The shape of a loop can easily be changed by stretching the fabric in all directions.

• The elasticity of knitted fabrics makes them favorable for sports’ wear, casual wear and hosiery.

• This elasticity, however, will be deterioriate due to over stretching, washing or ageing and eventually, the loops cannot recover to its original shape.

• This change of shape is called distortion or poor dimensional stability

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General Characteristics of Single Knit Fabric

1) Fabric Elasticity • A loop is a very short length of yarn bent into a OMEGA shape as shown on the black area

Page 13: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

General Characteristics of Single Knit Fabric

1) Fabric ElasticityThe dimensional stability of single knitted fabrics can be improved by:• Increase the fabric density, by using smaller loop

length to give the fabric higher cover factor.• Warp and weft insertion, by inserting straight yarns

to the fabric and bind the loops together to reduce their freedom of movement

• Apply resin finishing, a resin chemical can set the fibres and loops on fabric.

• Use the thermal plastic yarns, man-made fiber like polyester or nylon can be set at high temperature and maintain the loop shape on knitted fabrics.

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General Characteristics of Single Knit Fabric

2) Edge Curling

– Almost all single knit fabrics will curl on the edges when cut.

– It is the unbalanced loop structure and the yarn torque inside the fabric which tends to recover the original shape of the yarn.

– It is the edges of a piece of fabric that is free for movement, therefore, the edges curl.

• .

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General Characteristics of Single Knit Fabric

2) Edge Curling

The curling on the fabrics edges is one of the disadvantages of single knit fabircs.– It gives problems to the cutting, sewing and linking

processes. – Edge curling can be reduced by the following:

• Wet finishing, high temperature treatment like sourcing, bleaching and dyeing can remove the torque in the yarn and fabric.

• Stentering or steam pressing, stentering is used on open width piece goods, and steam pressing for knitwear panel and garment.

• .

Page 16: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

General Characteristics of Single Knit Fabric

3) LadderingWhen a loop in the fabric is broken, the loop directly underneath it will slip off and become a short length of horizontal line instead of maintaining the OMEGA shape.If a vertical row of loops slip off from the fabric, it looks like ladder.

Page 17: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

General Characteristics of Single Knit Fabric

3) LadderingLaddering is a fabric fault which affects the fabric appearance. Laddering will easily occur when:• The fabric is loosely knitted;

• The yarn frictional index is low;

• The fabric is plain knit;

• There is a big knot in yarn during knitting;

• The needle head is broken.

Page 18: Introduction to Textile Fabric Part 1: Basic Knitted Fabricslibvolume8.xyz/.../simplegeometryofknitstructurespresentation2.pdf · Content • Difference between woven and knitted

General Characteristics of Single Knit Fabric

4) Fabric AppearanceAll single jersey fabrics have different appearance on two sides

Looking on the face side, the fabric seems to be composed by thousands of “V” loops; while on the back side, the loops appear to be semi-circles.

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Discussion• Discuss the difference between woven fabrics and knitted fabrics

• Discuss the general characteristics of single knit fabrics