BRAIDINGTECHNIQUE

Braiding began as a handicraft for theconstruction of decorative fabrics but thelimitations of knitting and weaving madebraiding an important method of fabric

formation in textile composite, rope etc.

Introduction

The limitations of the weaving,knitting and stitching processesinclude:

poor shear resistance, limited strength in the primary

loading direction, and the inability to produce complex

shaped parts

Limitations of other fabricstructures

What is Braiding Technique?

Braiding is a simple form of narrowfabric construction. It is done byintertwining of yarns in whatever

direction suited the maker's purpose.

GeometryBraid structures are specifiedby the line and stitchnumbers.The width L is called a lineThe length S is called a stitchor pick.W is the width of yarn fromwhich the braid is made.α is the braid angleWhich specifies the angle bywhich the yarns lay fromdirection of machine axis?Braid angle is determinedfrom the relation between thetake-up speed and carrierspeed.

Types

Braiding can be classified as two andthree dimensional braiding.

Two-dimensional braid structure canbe circular or flat braid.

Three-dimensional braiding isrelatively new and was developedmainly for composite structures.

Two-dimensional braidingTwo-dimensional circular or flat braid is formedby crossing a number of yarns diagonally sothat each yarn passes alternately over andunder one or more of the others. The mostcommon designs in two-dimensional braidsare as follows: Diamond braids: 1/1 intersection repeat. Regular braids: 2/2intersection repeat. Hercules braids: 3/3intersection repeat.

Circular braiding-mechanismCircular (tubular or round) braids are formed hollowor around a centre core. A circular braiding machineconsists of two sets of an even number of spoolscontaining the braiding yarns. One set runs clockwisearound the centre of the machine and the other setturn in counterclockwise direction. While revolving inopposite directions, the carriers are diverted to passalternately inside and outside (under and over) oneanother. The clockwise and counterclockwise pathscause the two sets of yarns to intersect, thusproducing a tubular braid. The Maypole danceprinciple is applied here.

MAYPOLE DANCE PRINCIPLE

Rotary braidingThe rotary braidingmachine is faster thanthe maypole braider.However, rotarymachines are lessversatile in terms ofmaking different shapesand they have lessnumber of carriers.

In ROTARY principle, the strand sources (carriers) followcircular paths centered about the axis of braid withdrawal,one half traveling in a clock-wise and the other half in acounter clock-wise direction. Braid is produced by positivelydisplacing strands from the outer carriers and over and underthe inner carriers.

CIRCULAR BRAIDING MECHANISM

ROTARY BRAIDING MACHINE

Flat braiding

Flat braids are made in the form of flat stripsor tape. In flat braiding, instead of followingtwo continuous paths, the carriers turnaround or reverse direction at two pointscalled terminals and then continue on theother direction, i.e., the track does notcomplete a circle.

3-D braiding

3-D braiding is an interesting concept ofcreating a two dimensional array ofinterconnected 2-D circular braids.

3-D braids are formed on two basic typesof machines which differ only in theirmethod of yarn carrier displacement.• The horn gear type machines offer

improved braid speed over the Cartesianmachines.

• Cartesian machines offer compactmachine size, comparatively lowdevelopment cost and braid architecturalversatility.

Types of 3D braiding machine

Horn gear braiding

Horn gear machines with square or circulararrangement are employed in the fabrication ofsolid braids. Present-day machines are limitedto 24 yarn carriers and therefore limit the sizeand shape of braid. The braider yarns areintertwined in helical paths through out thestructure.

Track plate

Horn-gear

Cartesian braidingThe basic Cartesian process involves four distinctCartesian motions of groups of yarns termed rowsand columns. For a given step, alternate rows (orcolumns) are shifted a prescribed distance relative toeach other. The next step involves the alternateshifting sequence of the first and second steps,respectively. A complete set of four steps is called amachine cycle. It should be noted that after onemachine cycle the rows and columns are returned totheir original positions.

WORKING PRINCIPLE CARTESIAN BRAIDING

End uses of BraidingEnd uses of Braiding Braiding is much more significant for industrial fabrics than

consumer textiles. Braiding is one of the major fabrication methods for

composite reinforcement structures, with increasingapplications of electrical wires and cables, harnesses,hoses, industrial belts and surgical sutures.

Examples of the relatively new application area of braidinginclude reinforcement structures of sporting goods(baseball bats, golf clubs, water skis, snow skis),aerospace and automotive parts.

Because of the special properties, braids can be found(often hidden) in many different applications. Someexamples: Clothes and shoes, candle wicks, sash cords,water ski ropes, mountaineering ropes, yachting ropes,parachute lines, fishing nets, mooring lines, medicalapplications such as catheters or dental floss, over braidedhigh-pressure tubes, ground cables or harnesses