Design and development of an equipment to measure the hand value of apparel fabric

Abstract:

A simple and low cost equipment for measuring fabrichand has been designed. This method is based on the nozzle extraction method,which measures the force generated while extracting a circular fabric specimenthrough a nozzle. Instrument gives a single value (specific handle force-SHF),which is easy to determine and understand. The designed equipment can be easilyused in garment industries, wet processing industries and fabric manufacturingindustries to know the hand of the fabric easily and quickly. Both small andlarge scale industries of India can utilize this equipment because of its lowcost and simple design compare to other system. In this paper an effort is madeto study the hand properties of silk blends with classic modal, micro modal,lyocell, cotton and 100% viscose, polyester and cotton of varying blendcomposition using "FABROFEEL EQUIPMENT". Results were analyzed andcorrelation study was done. It was found that all the low stress mechanicalproperties including specific handle force and peak force increases as silkcontent increases specific hand force for particular samples shows anincreasing trend. Cotton silk blended fabrics exhibits high specific handforce compared to other fabrics. This indicates the cotton blended fabrics aremore stiffer than other samples. Micro modal blended products shows moresuppleness compared to other blended products. As the tightness factorincreases in knitted fabrics, there is an increase in specific hand force inall the samples

1. Introduction

Fabric hand is one of the most widely used fabricattributes followed by both industry and the consumer in determiningacceptability of textile goods for their end uses. It also influences consumerspreferences and their perception of the usefulness of the product. Looking atthe importance of this property there have been a continuous efforts toquantify the fabric hand objectively. At present there are few instrumentsavailable for evaluating fabric hand objectively and the Kawabata evaluation systemfor fabric (KESF) is the most sophisticated among them. The main disadvantagesof this equipment are high cost, complexity and time consuming procedure thatrestricts its industrial applications, especially for small scale and appareltextile manufacturers, processors and merchandisers.

2. Materials and Methods

Introduction

This chapter is concerned with various types of yarnswhich have been used for knitting. The methods of producing them, the rawmaterial used and the various tests were carried out on them are described indetailed.

Materials

Commercially available silk, modal, lyocell, micro modaland cotton fibres were used in this study.

Development of Silk Blended Yarns

The blending of the material was carried out usingsandwich technique in Blow room. 50:50 and 35:65 ratio fibre blends were prepared from silk and other fibres respectively.

The blends were processed in Lakshmi Rieter line to produce 30Ne (20Tex) yarn.

Properties of Silk blended yarn

Properties of Silk blended yarn

Properties of other yarn

Fabric Production

Each yarn was used to knit a length of knitted fabric. The following weft knitting machines were used for the production of weft knitted fabrics from the yarns. The fabric were produced with nominal tightness factor of 15.30 and 16.20 and also the 100% polyester, viscose and cotton were produced with three nominal tightness factors of 13.50, 15.30 and 16.20.

Particulars of Samples Code

Particulars of Samples Code

Relaxation Treatment

Fully relaxed Starfish method

Knitted fabrics were washed and tumble dried for 5 times following the procedure suggested by Starfish project undertaken by the International Institute of Cotton (IIC), Manchester, UK. The steps involved are given below.

a)     Washing in domestic washing machine at 60⁰C

b)     Tumble dry until the fabric is dried

c)      Wet out in washing machine (rinse cycle)

d)     Repeat steps b & c 3 times.

e)     Conditioning the sample

Dry relaxation

The sample was kept for conditioning for a period of 24 hours at temperature of 25 2⁰C and RH 65%.

Apparatus:

A simple apparatus was designed for determining the handle force. The apparatus consists of a load cell, which is connected with an extraction rod. The extraction rod pulls the circular specimen through the cylindrical nozzle. The peak load required for extraction was found from the load cell. The force for every displacement of the fabric was also read continuously to obtain the force displacement curve. This curve is useful in finding out how the fabric sample behaves while extracted through the nozzle. The maximum load revealed on the load cell was noted down, and the mean readings were taken. The instrument was interfaced to computer.

Figure shows the apparatus used in this study Fig.2 shows the basic functions of the testing procedure. The forces involved in the initial deformation are related to the bending modulus and the shear stiffness of the fabric. The compression and fabric friction play a larger role as the fabric specimen is squeezed to the dimension of the ring. Fabric withdrawal force depends on the resistance to bending, shear, compression and sliding force. The forces generated depend not only on the fabric but also on the ring size; sample size and the maximum withdrawal force can be taken as a measure of the fabric handle.

The cylindrical nozzle is made up of highly polished steel. The inner hole radius of the cylinder is varied from 5mm to 14mm radius to suit all type of fabrics available for apparel purpose. The packing fraction used normally in the range of 18 to 36% in case of woven fabrics as per the studies conducted by Ning pan (1995). Various diameters had to be selected on the basis of weight/unit area of the fabrics

Results of Specific hand force and Peak extraction force of blends

Specific Hand Force (SHF)

Results of Specific hand force and peak extraction force of Viscose, Cotton &

Polyester Fibres (100%)

Specific Hand Force (SHF)

Correlation between Specific Handle force & drape coefficient

Note: There is direct correlation between blends, drape co-efficient and specific hand value. As the specific hand value increases the drape co-efficient also increases. In case of 100% fibres the correlation between SHV and drape co-efficient is good and here also it is directly related, i.e. as SHV increase drape co-efficient is also increases.

Results & Discussion:

1.      As the silk content increases SHF for the particular samples shows an increasing trend.

2.      Cotton-silk blended fabrics exhibits high SHF compared to other fabrics. This indicates the cotton blended fabrics are more stiffer than other samples.

3.      Micromodal blended products shows more suppleness compared to other blended products.

4.      As the tightness factor increases, there is a increase in the SHF in all the samples.

Conclusions

Effect of Tightness Factor on SHF

The fabric behaviour while extracting from the nozzle depends on low stress mechanical properties. While fabric is being extracted from the nozzle it is subjected to phenomenon tensile, compressive, bending, draping, buckling and shearing. From the results and the three way analysis done on various samples (S1 S16) at two different tightness factors following observations can be made. There is difference in the SHF of all the fabrics. Tightness factor has direct influence on the SHF. From the results of three way analysis, it can be observed that there is significant difference in the SHF values of fabrics at two different tightness factors. Knitted fabrics show higher SHF at higher tightness factor. As the loop length is reduced (keeping the linear density constant, the density of the courses and wales get increased.) Increase in the course and wale density leads the improvement in the compactness of the fabric. So while extracting compact fabric through the nozzle, it takes more force as, shear, bending, compressional components get increased. In case of 100% fibres even though there is a difference in specific hand force, these differences are not statistically significant.

Effect of Blend Ratio:

The results of SHF values of knitted fabrics for various blends are presented in the table. The three way variance analysis shows that the blend ratio has direct influence on SHF. Results for both t1, t2 shows marked variation in SHF, when the blend ratio is changed. It can also be observed that there is significant difference in the SHF values of various blends. From the results it can be seen that as the percentage of silk fibres in the blend increases the SHF values increase in all the cases. The reasons for the above observations may be explained as follows. Silk being comparatively stiffer, and surface friction properties of silk fabric are much higher compared to viscose/regenerated cellulose exerts more resistance and (shear, bending) while extracting the fabrics through the nozzle. As silk fibres have triangular C/S there is possibility of more frictional resistance for the fabrics to get extracted through the orifice. This shows that knitted fabrics become more stiff when the percentage of silk is increased.

Effect of Fibre characteristics:

From the results of SHF of different fabrics table the following observations can be made. There is no significant difference in the SHF values of the fabrics produced from the blends containing silk and regenerated fibres. But the significant difference is found in the fabrics containing cotton / silk and regenerated/silk blends. It shows that fabrics made from all the three types of regenerated fibres viz. classic modal, micromodal and lyocell fibres behave similarly, when they are extracted through the nozzle. This may be due to almost similar physical and mechanical properties of these fibres. In case of 100% fibres it is significantly different since they behave differently because of different origin.

References for the Paper:

1.      Journal: [1] Barker R.L., Radhakrishniah P., Woo.S.S.Hatch K.L., Markee N.L. and Maibach H.I (1990), In Vivo Cutaneous and Perceived Comfort Response to Fabric Part Ii: Mechanical and Surface Related Comfort Property Determination for Three Experiment Knit Fabric Textile Res.J. Vol. 60, pp 490-493.

2.      Book: [2] Booth J.E (1968), Principle of Textile Testing Butterworth Scientific, London. pp 272.

3.      Journal: [3] Subramaniam V., Malathi, S., Lokanadan B., Nirmala Kumari R.M. and Chandramohan, G. (1990), A Simple Method of Measuring the Handle of Fabrics and Softness of Yarns, J. Text. Inst., Vol.81, pp 94-97.

4.      Journal:[4] Subramaniam, V. and Amaravathi T.B.C. (1994), Effects of Fibre Linear Density An The Type of Cotton On The Handle And Appearance Of Polyester Fibre-Cotton Fabrics Producted from Rings Spun and Open End Spun Yarns, T. Text. Inst., Vol.85, pp 24-28.

5.     Book: [5]. B. Grover and D.S. Hamby, Textile Testing and Quality Control, Wiley Eastern Limited New Delhi -1988.

6.     Pan N, and Yen K.C (1992), Physical Interpretations of Curves obtained through the fabric extraction process for handle measurement, Textile RG, J.Vol.62, PP 279-290

7.    H.L Vijaya Kumar (2005) spirality and low stress mechanical properties of weft-knitted fabrics knitted from different types of silk and modified ring & rotor spun cotton yarns. Ph.D thesis, Dept of Textiles, Anna University, Chennai, India.

8.      Yen KC, Pan N, Zhao ST and Yang SR, (1988) A new approach to the objective evaluation of fabric handle from mechanical properties, Part I; objective measure for total handle Textile Res.J Vol 58, PP 438 444.

Authors:

Dr. HL Vijaya Kumar is the Principal of Army Institute of Fashion & Design, Bangalore & Mr. J. S. Muralidhar is the Head Of the Department of Bapuji Institute of Engg & Technology, Davangere.

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