effect of finishing on knit fabrics

School of Science and Engineering, Department of Textile Engineering

Southeast University

Effect of finishing on Knit Fabrics

Effect of finishing on Knit Fabrics 1



Introduction

Textile finishing is a term commonly applied to different processes that the textile materials undergo after pretreatments, dyeing or printing for final embellishments to enhance their attractiveness and sale apparels well as for comfort and usefulness.

Finishing process improves the physical properties of fabric like feel, softness, tensile strength, elongation, G.S.M, dia, shrinkage, spirality, twisting, and insulation properties.

Dhaka,15.05.2011 Effect of finishing on Knit Fabrics 2



The techniques of finishing depend on the following:

• Nature of the fabric, i.e. chemical composition, state, weave, etc. This determines the appearance, i.e. transparences, luster, fullness, weight, whiteness, etc.

• The physical properties of the fabric, i.e. feel, softness, stiffness, tensile strength, elongation, shrinkage property, insulation etc.

• The end-use of the material i.e. non-shrinking, non-creasing, stiffening etc.

• Receptivity of the fabric to various finishing operations, i.e. water-proofing, flame-proofing, rot-proofing etc.

• Susceptibility to chemical modifications.




Softness Lusture Pleasant handle Drape Dimensional stability Crease recovery Antistatic Non-slip Soil release

Finishing treatments are basically meant to give the textile material certain desirable properties like:




Definition of Finishing

Finishing is a term usually employed for process other than scouring, bleaching, dyeing or printing, to which the fabric are subjected to improve their appearance, properties & serviceability.




Classification of FinishesThe most common classifications are:

•Aesthetic finishes: •Functional finishesTextile finishes are also categorized as:

•Mechanical finishes (Dry finishes)•Chemical finishes (Wet finishes)




Classification of Finishes

Finishes can also be classified by their degree of performance as follows:

• Permanent finishes• Durable finishes• Semi-durable finishes• Temporary finishes




Controling parameter of finishing


• Dia of the fabric• GSM of the fabric• Shrinkage of the fabric• Weight loss or gain• Tension control• Temparature of different stage• Spirality control etc.• Color fastness of the fabric etc.



Finishing process

Dhaka,15.05.2011 Effect of finishing on Knit Fabrics.

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Unload fabric from Dyeing

Hydro extracting

Dryer/Stentering

Open compacting

Process of finishing for Open fabric



Finishing process


Tube form fabric

Dewatering

Dryer for drying

Tube compacting

Slitting

Stentering

Open compacting

Process of finishing for Tube fabric



Finishing terms


GSM:GSM means fabric weight in grams per square meter’s .

2

Fabric Weight In Grams

length In mGSM



Shrinkage:The amount of shrinkage for any given knit fabric is primarily dependent upon the product specifications and the knitting parameters used to meet those specifications.Formula of shrinkage % measurement:

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Finishing terms

Before Wash Length After Wash LengthLength Wise Shrinkage % 100

Before Wash Length

Before Wash Width After Wash WidthWidth Wise Shrinkage % 100

Before Wash Width



Finishing terms

Spairality:

“Spirality” arises from twist stress in the constituent’s yarns of plain fabric, causing all loops to distort and throwing the fabric wales and courses into an angular relationship

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Finishing terms

Color fastness:The stability of color or its fastness is one of the most important requirements of valuable customers. Colour fastness of dyed goods means the resistance power of dyed goods against any hazards.The color textiles show different resistance power to different agencies such as light, wash, rubbing, perspiration, water, bleach, acid, alkali etc.

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Effect of Hydro and Dewatering

If water remove from fabric is very much percentage than fabric surface show crease mark, this fault can’t be remove.

If length wise run the fabric then 20% shrinkage occurs. If breakdown occur of de-twister than puckering occurs. If twist problem occur than it effect on knit garments. If do not take proper ballooning than folding mark occurs.


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Effect of Hydro and Dewatering

If squeeze roller/padder pressure is high than fabric surface show pressure mark.

If over feed dia of delivery side is not perfect than length wise shrinkage occurs.

If dia increase than become poor shrinkage properties. Dia increase in this stage because it helps to better work for

dryer & slitting. Dia mark also occurs in this stage.


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Effect of slitting

If dia is less than basket dia than fabrics do not cut and if dia is greater than basket than GSM problem occurs.

Cut the fabric break wales line wise. Basket dia must be less then fabric dia.


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Effect of Stentering Over feed tension is very important for this stage. If over feed decrease than length increase. More over feed give in white fabric. If need light shade of the fabric than increase padder pressure. If need dark shade of the fabric than temperature increase 20˚C. For Lycra heat setting temperature need (190-200) ˚C. If half feeder Lycra fabric than increase speed and decrease temp. If full feeder Lycra fabric temp need 200˚C. Heat setting takes for width fixed of Lycra fabric.


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Effect of CompactingMany textile manufacturers have, and still do, rely on compaction as a means of shrinkage control. Compaction is a method whereby the course loops are compressed upon themselves. Different machines incorporate a variety of techniques to accomplish this. There are basically two classifications of compaction: heated rolls and shoe units or belt shrinking units. Both methods rely on speed differential and their patented compaction zones to accomplish the compaction. Tubular and open-width systems are available. The fabric is steamed to add moisture and then introduced to the compacting zone. The compaction mechanism, along with heat and moisture, forces the length stitches (courses) to be compacted.


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Results and discussion


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For finding the effect of finishing on knit fabric some experiment are done on different types of knit fabric.



Compare the GSM change for Single jersey and single jersey lycra fabric


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Grey Dyeing Slitting Stentering Compacting155

160

165

170

175

180

185

190

195

200

GS

M

GSM variation Stages

GSM

Grey Heat setting Dyeing Slitting Stentering Compacting

116

118

120

122

124

126

128

130

132

134

136

GSM



Compare the Variation of GSM for 1×1 rib fabric and Interlock fabric


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185

190

195

200

205

210

GSM


180

190

200

210

220

230

GSMChange



Compare the variation of GSM for fleece fabric and Pique


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Grey Dyeing Slitting Stentering Compacting Brushing

200

205

210

215

220

225

230

235

GSM

Grey Dyeing Slitting Stentering Compacting

170

180

190

200

210

220

GSM



Compare the shrinkage % change for Single jersey and single jersey lycra fabric


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Dyeing Slitting Stentering Compacting

-5

-4

-3

-2

-1

0

1

2

3

Shr

inka

ge%

width% length%

Dyeing Slitting Stentering Compacting-5

-4

-3

-2

-1

0

1

Width% Length%



Compare the Variation Shrinkage % for 1×1 rib fabric and Interlock fabric


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-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

length% width%


-3

-2

-1

0

1

Length% Width%



Compare the shrinkage % of fleece fabric and Pique


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-1.5

-1.0

-0.5

0.0

0.5

1.0

Length% Width%


-4

-3

-2

-1

0

1

2

3

length% width%



Spirality % change for Single jersey and single Spirality % change for Single jersey and single jersey lycra fabricjersey lycra fabric


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0.5

1.0

1.5

2.0

2.5

3.0

Spirality%

Dyeing Slitting Stentering Compacting0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Spirality%



Spirality % change for 1×1 rib fabric and Interlock fabric


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0.5

1.0

1.5

2.0

2.5

Spirality%


1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

Spirality%



Spirality % of fleece fabric and Pique



1.0

1.5

2.0

2.5

3.0

Spirality%


1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

spirality%



Discussion




References

• http://www.thesmarttime.com• Books of Finishing ,By-Petro Bellini,Ferruccio Bonetti.• Lecture sheet of Dr. Zulhash Uddin • Experimental data from Paddma poly cotton knit fabrics

Ltd.




Acknowledgement

We would like to express many thanks to our honorable teacher Md. Fazley Elahi for giving us a very good opportunity for presenting ourselves. We also thanks our parents who encouraged us every step of our life. Lastly thanks all of you who are give kind attention for this presentation ceremony




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Thank you ALL for your Attention

Dhaka,15.05.2011 Effect of finishing on Knit Fabrics

effect of finishing on knit fabrics

Engineering

southeast

textile engineering

textile engineering

textile engineering

textile engineering

physical properties

dia increase

knit fabrics