BAHIR DAR UNIVERSITY

Ethiopian Institute of Textiles and Fashion Technology(EITEX)

SEMINAR ON 3D KNITTING PREPARED BY: SELAMU TEMESGEN SUBMITTED TO : Dr.S.Kathirrvelu (Professor Textile Tech.

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Contents

Introduction Classification of 3D knitted fabrics Manufacturing method for 3d textiles Properties of weft and warp knitted 3D fabrics Types of machines used for 3D weft and warp

knitting Application of 3D fabrics Principles to obtain 3d knitted fabrics

3D-Textiles 1.Introduction

Development of three-dimensional knitted fabrics dates from the 19thcentury

• The concept of three-dimensional of the textile materials is not related to the intrinsic value of dimensions found on the three axes (x, y, z), but to the relationship between them.

• This relation characterises the importance of the dimensions in the geometry of the material.

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• A three-dimensional fabric, regardless of the process used, is “a continuous ensemble, with fully integrated fibre, characterised by multiaxial spatial orientation” Creating a three-dimensional effect on knits is based

on the following techniques: • I. Insertion of additional yarns along multiple

directions; • II. Knitting and linking independent layers in

different ways; • III. Spatial shaping.

2. Classification of 3D knitted fabrics

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3.3D Textiles - Manufacturing

Methods Manufacturing methods:

Braiding Weft knitting Warp knitting Weaving Stitched assemblies

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Manufacturing Methods –Weft

Knitting • Basic technique:

– Forming a loop through previously formed such loops.

• One yarn makes one row of the fabric.

General properties: – The specific shape of the individual loops results in an elastic material – Fabric thickness is low – 3D geometry – Patterning allows manufacturing of tailor-made shapes 7

Fabric Formation Elements– Weft Knitting

Individually controlled needles Consecutive knitting on every next needle One thread per row

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4. Machines used –Weft Knitting

Two kinds of machines: • – Flat bed • Possibility to make tubular products, shells, thickness

reinforced (spacer knits) and some complex structures as a combination of these

• Patterning of shape and loop architecture • – Circular • Tubular and spacer tubular fabrics

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5.Application Scope –Weft Knitting

Weft Knitting:

• – Somewhat limited 3D application due to the relatively low thickness of the material

Biomedical

Composites (formable matrix)

Reinforcement (Y-pipe, T-Pipe)

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Manufacturing Methods –Warp

Knitting

• Basic technique: • – Fabric formed by interconnecting loops. • Machine used-Double needle bar raschel is commonly used • A set of individual yarns for every needle. • General properties: • – Less elastic fabrics • – Products with considerable thickness – 3D structures • – Patterning allows repeated structures to be manufactured

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Fabric Formation Elements– Warp Knitting

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Application Scope –Warp

Knitting • Warp Knitting:

Composite materials Aerospace industry – composite matrix Civil engineering – concrete reinforcement, acoustic

insulation Military - ballistic protection Biomedical – vascular stents

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5.Principles for Obtaining Three-Dimensional Knitted Fabrics

• To produce three-dimensional fabrics, the knitted material can be

formed by the technique called spatial fashioning technique (also known as flechage). Three-dimensional structures can be created also

by knitting stitches and loops combined with the lateral movement of the needle bed. By increasing or decreasing the number of working

needles it is possible to create three dimensional knitted items on intarsia knits.

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Conti…… The methods of making three-dimensional items on

flat knitting machines are: 1. Incomplete knitted rows technique (spatial

fashioning); 2. The use of patterns with 3D effects – egg. Knitting

tuck stitches patterns combined with racking; 3. Knitting separate fabrics connected in between –

sandwich/spacer fabrics; 4. Integral knitting /wholegarment.

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Conti……… 1. Incomplete Rows Knitting Technique • Incomplete rows knitting technique is a

technique used by designers of knits to create three-dimensional knitted items or tubular knits

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2.Use of Patterned Structures with 3D Effects

• The most known example is the so called egg nest fabric, created by

Shima Seiki. • The pattern is based on cardigan evolutions combined

with successive racking in opposite directions. • Another example is a jersey fabric with a zone with miss stitches while the carriers produce

stitches on the opposite bed.

• When the missing stitches are discharges, the stitches produced on the opposite bed are transferred to the working bed.

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3. Sandwich Fabrics • A knitted layered item (sandwich) is a 3D structure,

composed from two outer layers knitted together independent, connected by byarns or other knitted layers, as shown below

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Sandwich fabrics with connection through knitted layers present a large range of development possibilities : − increase in the fabric thickness based on the length of the connection layers; − modification of the geometry of external fabrics due to the use of connecting layers with different length;

4. Integral Knitting Technique Integral knitting technique is an improved stage in the development of

technologies for flat knitting machines . So far it is the most advanced knitting technology through

which a garment is completely assembled on a knitting machine without the need of sewing. Seamless knitting technology is a method that cuts off waste and reduces costs.

• The seamless garment is very comfortable and resistant to wear.

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THE END THANKS

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