Development of System for Online/Offline

Quality Control of Nonwoven Fabrics/Functional

Fabrics

using Digital Image Processing Techniques

Ph.D. Synopsis

Submitted To

Gujarat Technological University

For The Degree

of

Doctor of Philosophy

in

Textile Engineering

By

Ms. Krishma S. Desai

Batch: 2011

Enrollment No: 119997125001

Textile Engineering

Supervisor Co-Supervisor

Prof. (Dr.) P. A. Khatwani Dr. Hamed SariSarraf

Sr. Professor & Head,

Department of Textile

Technology, Sarvajanik

College of Engg. & Tech.,

Surat, India

Professor, Electrical and

Computer Engineering,

Texas Tech University,

Box

43102 Lubbock, TX

794093102

1

Title of the thesis:

Development of System for Online/Offline Quality Control of Nonwoven

Fabrics/Functional Fabrics using Digital Image Processing Techniques

Abstract:

As a result of globalization & also increasing competition, it has become very important

for any industry to develop solutions regarding the quality of products. Effective

monitoring and control, better data predictions, quick response to query is necessary for

effective Quality Control. The research work intended here is to develop an

online/offline quality control system for different types of nonwoven fabrics/variety of

functional fabric by developing mathematical models and using digital image

processing.

Brief description on the state of the art of the research topic:

Functional Fabrics or more commonly known as the Technical Textiles are the fabrics

manufactured primarily for their functional/technical and performance properties rather

than just their aesthetic appearance. The qualities and properties of

nonwoven/functional fabrics are influenced largely by factors like type & structure of

raw material, type of fabric-woven, knitted, nonwoven, special fabrics, etc. which also

influence the surface texture of the fabric. Thus the visual inspection of the fabrics is an

important aspect in assessing the quality of the fabrics.

Human Visual Inspection of fabrics have been a criteria for Visual Assessment of fabric

quality in the Textile Sector since long. It included the detection of fabric defects

generally. However, this method cannot detect more than 60% of the overall defects for

the fabric if it is moving at a faster rate and thus the process becomes insufficient and

costly. Therefore, automatic fabric defect inspection is required to reduce the cost and

time waste caused by defects.

Available commercial systems comprises[31] of visual inspection systems, which

detects some of the defects in the fabrics mostly used for apparels. These systems are

too expensive for small companies. Therefore, a lot of studies are being done to use PC-

2

based real time inspection systems, which gives the benefits of low cost and high

detection rate. It also offers the scope of experimenting for improvement in assessment

of the fabrics. It offers a scalable open architecture and can be manufactured at

relatively low cost using off-the-shelf components was required. Also this type of

systems for quality control would give the benefits of low cost.

On going through extensive literature survey in the said area it has been found that the

use of real time vision based/ image recognition or processing has been an effective tool

for detection of variation in textiles. The various approaches after the detection of the

defects for effective quality control of textiles are discussed below:

A paper[12] by Image Ghith, Fayala & Abdeljelil on Assessing Cotton Fiber Maturity

and Fineness proposes a maturity analysis of fibres by image analysis, where structural

variability is studied for analysing maturity and fineness. Another paper[9] by Das,

Isthiaque & Mishra shows the studies carried out for assessing the fibre openness using

Image Analysis Technique. Image analysis is an attractive alternative to existing

systems for investigating some quantitative fibre characteristics. It is quick, reliable and

unbiased technique which is used to evaluate fibre characteristics.

A lot of studies have been done in the area of defect detection for quality control in the

area of woven fabrics[1], [4], [7], [14]. Initial studies in this area had been done in the

area of woven fabrics in 1999, using a defect segmentation algorithm[13]. Then after

many algorithm using local threshold technique, using various filters, etc. has been

studied upon for defect detection in the woven fabrics mainly for the ones being used

for the apparel.

A limited study has been done in the area of assessing structural variability in the area

of nonwovens as well as functional fabrics. Also the studies done in the area of

nonwovens is largely limited to measurement of fibre orientation in the web rather than

defect detection & analysis, which becomes a complex process due to the fibrous

structure of nonwovens. The Studies [36] proposed by S. Hariharan, S. A. Sathyakumar,

P. Ganesan on measuring of fibre orientation in nonwovens using image processing but

not on detection of the faults and their classification. Paper describes the application of

3

image processing techniques for measuring the fibre orientation in nonwovens. Spatial

uniformity of fibrous structures have been described statistically by using index of

dispersion.

Results shows the technique is capable to identify variation in geometrical dimensions

of very small textile objects. By elaborating the digitization algorithm along with

numerical methods would give solutions for obtaining characteristics of nonwovens and

thus improving the quality.

Definition of the Problem:

The survey of the papers gives an idea of the different approaches that have been

considered in designing quality control systems in the area of textiles. The study shows

that limited studies have been carried out for defect detection of nonwovens and

functional fabrics and therefore offers scope of further research in the said area.

With the increase in number of applications of technical textiles in different areas

during the days to come, it becomes necessary to design and develop the system to

check the quality of such varieties of fabrics in much shorter time and with utmost

accuracy.

The visual uniformity of the fabrics will be detected by a cost and quality effective

device to be developed during this research work.

Objective and Scope of work:

To develop cost and quality effective system for targeting mainly the growing

Indian Technical Textile Market.

To help the user in selection of proper quality of nonwoven/functional fabrics

for specific end use applications.

To help the user to avoid unnecessary wastage of time and materials, which

otherwise would be due to wrong selection of materials for any specific

application

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Very bright prospects ahead for the system to be developed considering very

high market growth from 10 billion dollars in 2009 to expected 31 billion dollars

in 2020.

Original contribution by the thesis:

The entire work is the original work, with the filing of patent under process and well

supported by the research papers. The developed system has been considered as a

combination of different similar systems available for such applications.

Methodology of Research, Results / Comparisons:

We have used qualitative as well as formulative approach for this research work. The

structure/qualities and properties of nonwoven/functional fabrics are influenced largely

by factors like type & structure of raw material, type of fabric-woven, knitted,

nonwoven, special fabrics, etc. which also influences the surface texture of the fabric.

Process Flow Chart of Developed System (Fig. 1):

Fig. 1: Process Flow Chart of Developed System

Device Development Image Acquisition Fabric

Sampling

Image Processing

• Enhancing Images

• Extracting Features Classification

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Device Development for Quality Monitoring(Fig. 2):

Fig. 2: Device for Quality Monitoring

Sampling:

• Fabric Sampling.

• Image Acquisition using the developed Device

Fabric Sampling:

6 different varieties of functional fabric including woven as well as nonwoven fabrics

were manufactured for the study. The defects obtained in the manufactured fabric were

a result of the fabric manufacturing process and were assessed visually as well as with

the software developed using the proposed algorithm using MATLAB. However, the

experts from IIT had suggested to consider only one variety of fabric preferably

spunbond nonwoven fabric during the Research Week held during month of April 2015

at Gujarat Technological University, Ahmedabad. They had also suggested to consider

some of the major defects occurred during the manufacturing of spunbond fabrics. Also,

validate the results so obtained by taking multiple images of same defects. After

considering the inputs from the experts of IIT, the study has been narrowed down to 2

6

varieties of functional fabrics i.e. Woven Geotextiles & Spunbonded Nonwovens. 7

types of defects in each variety has been focused on in the study.

The details of the samples are shown as below:

• Woven – Geotextiles - Manufactured at M/s. Technofab, Udhana Magdalla Road,

Surat

• Machine Specifications:

– Sulzer Projectile Loom

• PU model loom

• 3.5 m and 5 m width

• Speed-230 rpm for 3.5 m & 180 rpm for 5 m

Sample

Name

epi x ppi warp x weft Denier GSM

G1 38 x 24 720 x 400 160

G2 38 x 26 400 x 400 120

G3 34 x 24 800 x 800 215

G4 38 x 24 660 x 660 210

G5 21 x 21 2000 x 2000 290

G6 36 x 24 720 x 720 210

G7 34 x 26 1000 x 1000 220

List of defects identified:

Sr.

No.

Fabric

Defect

Definition Principal Causes Remedy

1. Missing

End

(Chira)

There may be one

end or a group of

ends missing in

the fabric.

If the broken ends are

not mended

immediately by the

operator, these missing

ends will occur in the

fabric.

This defect can be

minimised (a) by

minimising missing

ends in the weaver’s

beam & (b) by

providing an efficient

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warp - stop motion on

a loom.

2. Slubs

(Warp)

Thick untwisted

portion in warp

yarn

Variation in draft during

spinning.

Set the draft as per the

requirement.

3. Stain

(Daggi)

These stains are

due to lubricants

or dust.

improper material

handling, bad oiling &

cleaning practices

By proper material

handling as well as

good oiling & cleaning

practices, this defect

can be avoided.

4. Slubs

(Weft)

Thick untwisted

portion in weft

yarn

Variation in draft during

spinning.

Set the draft as per the

requirement.

5. Missing

Pick

(Jerky)

It is a strip which

extends across the

width of fabric &

has the pick

density lower

than the required

one.

It is caused by faulty let

- off & take - up

motions. Also, if the

loom is not stopped

immediately in case of

weft break, few picks

are liable to be missed

in the fabric.

This defect can be

remedied by proper

setting of let - off &

take - up motions &

also by using an

efficient brake -

motion.

6. Gout Foreign matter

woven in a fabric

by accident.

Usually lint or

waste.

It is caused when the

hardened fluff or foreign

matter such as pieces of

leather accessories,

pieces of damaged

pickers etc., is woven

into the texture of the

fabric.

This defect can be

remedied by

preventing the foreign

matter from falling

onto the warp between

the reed & the fell of

the cloth.

8

• Nonwoven-spunbonded- Manufactured at M/s. Wovlene Tecfab India, A-42/5,

Ichchhapore G.I.D.C, Near GEB Substation, ONGC Road, Hazira, Surat-394510.

• Machine Specifications:

– Chinese make spunbonded machine -1.6 m width

– Capacity : 5 tonnes/day

– GSM range :10 -200

Sample Name GSM

NS1 40

NS2 60

NS3 60

NS4 60

NS5 60

NS6 85

NS7 120

NS8 135

NS9 60

NS10 60

NS11 80

List of defects identified:

Sr.

No.

Fabric

Defect

Definition Principal Causes Remedy

1. Drops /

bond point

fusion

Fused fibres on

surface

Breaking of bundle of

filaments during the

process.

Proper setting of draw

ratio.

2. Pinholes Very small

holes in fabric

Damaged surface of

delivery roller.

Filing of surface of

roller.

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3. Wrinkles Wrinkle

formation

Improper tension

across the width of

fabric.

Maintaining uniform

tension.

4. Hard

filaments Fused

filaments on

surface

Breaking of filaments

during the process.

Proper setting of draw

ratio.

5. Hole Holes in fabric/

web

Improper supply of

polymeric material

across the width of

fabric, blockage of

spinnerette holes.

Maintaining proper

supply of polymeric

material across the

width of fabric, cleaning

of spinnerrrate.

6. Calendar

cut Cut marks due

to calendaring

Rough surface of

calendar roll.

Polishing of surface of

roller.

7. Thin spots Low density of

fibres in a

particular area

Improper supply of

polymeric material

across the width of

fabric.

Maintaining proper

supply of polymeric

material across the

width of fabric.

Fabric Image Acquisition: More than 200 images of different fabric samples were

captured using CMOS camera.

Methodology involved in Image Processing:

The captured images were processed using MATLAB. Various parameters like mean,

sd, histogram of the intensity values were studied for estimating & identifying the

standard images. The images of the samples with defect were then processed for

obtaining the defect statistics.

The proposed algorithm will check for variability and give defect statistics and classify

as per Defect Area. It will also check for no. of Defects in the Fabric Lot and give %

Defects in the Fabric. On the basis of the defect statistics a fabric grading system has

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been developed which will classify the fabric for specific application. The sequence of

steps followed in the processing of the images is shown in fig.3.

Fig. 3: Steps involved in Image Processing of Images for Defect Classification

Image of Fabric

Gray Level Conversion

Contrast Adjustment

Histogram

Thresholding

Binary Image

Morphological Operations

Feature Extraction

Classification

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Accuracy of Detection of Variability:

The Defect Statistics obtained from the software were compared with the values

obtained by manual visual examination of the defects. The defective percentage

accuracy of the results for geotextiles and spunbonded fabrics has been shown in Fig. 4

& Fig 5.

Fig. 4: % Accuracy for Geotextiles

Fig. 5: % Accuracy for Spunbonded

0

10

20

30

40

50

60

70

80

90

100

MissingEnd

(Chira)

Slubs(Warp)

Stain(Daggi)

Slubs(Weft)

MissingPick

(Jerky)

Gout

% Accuracy

% Accuracy

0

20

40

60

80

100

120

% Accuracy

% Accuracy

12

Validation of Results:

Multiple Images of same samples had been taken to validate the results. CV% of the

defect statistics obtained for multiple images of each type of defect was calculated.

About 5-10% CV was found.

Fabric Grading:

On the basis of the defect parameters obtained as result of the processing of images of

the fabric lot & considering the proposed classification of defect, a fabric grading

system was developed. The Defect Classification is shown in Table 1.

Defect Name (DN) Woven Geotextile Spunbonded Nonwoven

Missing End (Chira) Drops / bond point

fusion

Slubs (Warp) Pinholes

Stain (Daggi) Wrinkles

Slubs (Weft) Hard filaments

Missing Pick (Jerky) Holes

Gout Calendar cut

Thin Spots

Defect Size (DS) Mendable- 10 % Defective Area

Permissible- 30% Defective Area

Critical - 60% Defective Area

Rejected - 80% Defective Area

Defect Frequency (DF) Frequency of occurrence of defects

Defect Orientation (DO) Machine Direction/Warp Way

Cross Direction/Weft Way

Table 1

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The Proposed Grading System is shown below:

Grade of Fabric Proposed Performance of Fabric

A (Best) The defect has no or very negligible influence, the fabric can thus be

used for suggested applications.

B (Good) Substandard applications of suggested areas are possible with this

grade of fabrics.

C (Poor) Can be considered after repairing or taking preventive measures for

suggested areas of applications.

D (Rejected) Not to be considered for any suggested applications.

Achievements with respect to objectives:

Successfully designed & developed prototype of device well supported with the user

friendly software module to help the users:

In selection of proper quality of nonwoven/functional fabrics for specific

end use applications

To avoid unnecessary wastage of time and materials, which otherwise

would be due to wrong selection of materials for any specific application

Mainly dealing with the development of functional textiles having very

high growth potential during the days to come

Conclusion:

• Designed & developed prototype device for monitoring the quality of

nonwoven/functional textiles.

• Prepared algorithm for development of software module most suitable for

different varieties of fabrics.

• Tested nonwoven fabrics for different quality parameters and validate the results

so obtained by capturing multiple images of same fabric samples using image

processing technique. The results show the variability of the order of only 5-10

% which is considered to be negligible.

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• Tested other functional fabrics for different quality parameters and validate the

results so obtained by capturing multiple images of same fabric samples using

image processing technique. The results show the variability of the order of only

5-12 % which is considered to be negligible.

Copies of papers published and a list of all publications arising from the thesis:

INTERNATIONAL:

1. ―Industrial Fabrics used in Conveyor & Power Transmission Belts‖ – paper

published in the Proceedings of 6th International Conference on ―Advances in

Textiles, Machinery, Nonwovens and Technical Textiles‖ held during 7th -9th of

December 2009 at Bannari Amman Institute of Tech., Sathyamangalam, Erode

District, Tamilnadu, India , organized jointly with Texas Tech University,

Nonwovens & Advanced Materials Laboratory, The Institute of Environmental &

Human Health, Lubbock, USA

2. ―Quality Parameters for Medical Textiles and Their Assessment‖ - paper published

in the Proceedings of MEDITEX-2014 International Conference on ―Current Trends

in Medical Textile Research‖ organized by Centre of Excellence In Medical

Textiles, The South India Textile Research Association, Coimbatore, Tamil Nadu,

India and sponsored by Office of the Textile Commissioner, Ministry of Textiles,

Government of India on 1st March, 2014.

3. ―Quality Parameters for Baby Diapers and Their Assessment‖ - paper published in

the Proceedings of INDO – CZECH INTERNATIONAL CONFERENCE on

―Advancements in Specialty Textiles and their Applications in Material Engineering

and Medical Sciences (ICIC 2014) ‖ organized jointly by Department of Textile

Technology / Department of Fashion Technology, Kumaraguru College of

Technology, Coimbatore and Technical University of Liberec, Faculty of Textile

Engineering, Czech Republic during 29th-30th April, 2014.

4. ―Development of Eco Friendly and Cost Effective Solutions for Packaging

Industries‖- paper published in the Proceedings of International Conference on

―Technical Textiles and Nonwovens‖ organized by IIT Delhi during 6-8 November,

2014 at IIT Delhi.

15

5. ―Development of Conductive Fabrics and their Applications in Textiles‖ – in

TEXTILE ASIA, p.29-32, Dec. 2011.

6. ―Developments in Medical Textiles for the Need of the Day‖- paper published as a

Poster at the International Conference on ―Technical Textiles and Nonwovens‖

organized by IIT Delhi during 6-8 November, 2014 at IIT Delhi.

7. ―Quality Requirements For Woven Fabrics Used As Functional Textiles‖, paper

published in the Proceedings of the Global Textile Congress organized by The

Textile Association (India) in association with Thailand Convention & Exhibition

Centre, Thailand Theme : ―Global Textile – Opportunities & Challenges in an

Integrated Word‖ during 13-15 February, 2015 at Ambassador Hotel (Convention

Hall ), Bangkok, Thailand.

8. ―High Performance Nonwovens for Infrastructural Developments in India‖ – paper

published in the Proceedings of the Second International Conference on Nonwovens

for High Performance Applications organized by the International Newsletters Ltd.,

UK during 4-5 March, 2015 at Novotel Hotel, Cannes, France.

NATIONAL:

9. ―Influence of Properties of Back-Up Fabrics on Properties of Synthetic Leather‖ in

Journal of the Textile Association. May-June, 2014, Vol. No. 75 No. 1 pg.39.

10. ―A Review of Detection of Structural Variability in Textiles using Image Processing

and Computer Vision‖ in Journal for Research| Volume 01| Issue 12 | February 2016

ISSN: 2395-7549, pg. 46-50

Patents: Filed Provisional patent with Application No. TEMP/E-1/11942/2016-MUM.

16

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