Fabric shear rigidity is higher in warp direction for plain weave fabrics and it affects the seam puckering quality more than seam efficiency, find Sumit Mandal, Dr Frency Ng, and Dr Patric Hui.

In modern high speed sewing machine fabric and sewing thread is subjected to complex kinematics and dynamic conditions ^[1]. The speed at which sewing thread passes through the needle eye can reach 140-150 km/hr and at the moment at which the thread is caught by the sewing hook, the speed reaches 2000m/sec ^[2]. Such speed applies stress on the fabric and sewing thread. This strain is the cause of susceptible defects to the seam line during seaming, resulting in deterioration of the seam quality.

Seams are to have satisfactory appearance and serviceability from quality point of view ^[3]. The prime contributors in this matter are the fabric properties ^[4]. Shear rigidity is one of the most important fabric properties ^[5]. Correct selection of fabric shear rigidity requires consideration of their performance properties during sewing as well as their performance in the completed garments under conditions of wear ^[6].

In 2004, Lam & Postle claimed that fabric shear rigidity affected the seam quality ^[7]. In the same year, Hunter & Fan argued that fabric shear rigidity affected the clothing fit and appearance ^[8]. In 2003, Pavlinic & Gersak investigated the relation between fabric shear rigidity and seam quality ^[4]. The authors corroborate that fabric shear rigidity has immense impact on seam quality, especially the seam appearance. In 2002, Gersak asserted that seam quality also depended on fabric shear rigidity ^[9]. In 1999, Mori, Haga & Takagishi discussed that fabric shear rigidity have impact on fabric handle that ultimately affected the quality of the garment ^[10].

A literature review of above showed that some researchers, however, have queried the claimed benefits of shear rigidity and whether shear rigidity provides opportunities for required seam quality. However the above review showed that little empirical research has been done on the effect increasing the fabric shear rigidity on seam quality. Thus based on statistical analysis, the authors' research aims at better understanding on the effect of shear rigidity on seam quality.

Experimental

Materials

Plain weave cotton fabrics were selected for the study. The details of fabric samples used are given in Table I.

Table 1. Fabric Details

Methods

Fabric shear rigidity measurement

The Kawabata Evaluation System (KES-FB) was used for measuring shear rigidity of the fabric of the fabric sample 1-8. The shearing test for measurement of shearing rigidity was conducted by employing the KES-FB1 measuring systems. The parameters obtained from KES-FB1 systems are defined in Table II. All measurements were repeated for the five samples and averaged.

Table II. Parameters obtained from KES-FB2

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Sewing

Sewing was done on the industrial sewing machine under particular sewing conditions that are commercially adopted by apparel manufacturers in apparel manufacturing. The most conventional plain seam (ISO 1.01.01) was selected for the study. All samples were sewn by single needle lockstitch (ISO 301) in both warp and weft direction. The standard sewing conditions maintained for the test sample were as follows: Machine speed: 3000 stitches per minute

Linear stitch density: 10 stitches/inch.

Needle size: 11

Sewing thread ticket number: 120

Feed-dog tooth pitch (mm): 1.5

Seam quality analysis

Measurement of the seam quality was done by studying the seam efficiency, seam puckering. Seam efficiency was calculated using the following formula ^[9]:

                                          Seam Strength Tensile (%)
 Seam  efficiency (%)  =          X  100
                                          Fabric Tensile Strength

Seam pucker was determined by measuring the difference in fabric and seam thickness under a constant compressive load. The seam thickness strain was calculated using the formula [11]:

Thickness Strain (%) = (ts-2t)/2tX 100
[Where, ts= Seam thickness, t= fabric thickness]

Results analysis and discussion

Results of shear rigidity of fabric samples

The shear rigidity of fabric samples in warp and weft direction is recorded in Table III.

Table III. Shear rigidity properties.

Results of seam quality of fabric samples

The results of seam efficiency in warp and weft direction of fabric samples which are sewn under above mentioned sewing condition are recorded in Table IV.

The results of seam puckering in warp and weft direction of fabric samples which are sewn under above-mentioned sewing condition are recorded in Table V.

Graphical representation of fabric shear rigidity and seam quality in warp direction

The graphical representation between fabric shear rigidity and seam quality in warp direction are given in Figure I.


In the graphical analysis, it was found that the fabric shear rigidity in warp direction would be indirectly correlated with seam puckering, thus showing that increasing the shear rigidity will help to decrease the seam puckering. It is also observed that fabric shear rigidity also positively correlated with seam efficiency; however no clear-cut trend was observed in that case. Thus, the fabric structural property of shear rigidity would affect the seam quality of the fabric.

Graphical representation of fabric shear rigidity and seam quality in weft direction

The graphical representation between fabric shear rigidity and seam quality in weft direction are given in Figure II.


In the graphical analysis, it was found that the fabric shear rigidity in weft direction would be indirectly correlated with seam puckering, thus showing that increasing the shear rigidity will help to decrease the seam puckering. However seam puckering value is higher in weft direction as fabric shear rigidity is generally lower in weft direction than warp direction. It is also observed that, fabric shear rigidity also positively correlated with seam efficiency; however no clear-cut trend observed in that case. Thus, the fabric structural property of shear rigidity would affect the seam quality of the fabric.

Conclusion

After experiments, it was found that shear rigidity is higher in warp direction for plain weave fabrics. It was also found that the fabric shear rigidity would affect the seam quality of the fabric samples. However shear rigidity would affect the seam puckering quality of the sample more than seam efficiency. It implies that the apparel manufacturer should pay more attention during on shear rigidity of fabrics when less seam puckering is the considerable requirement as seam quality. Such findings are very useful for selection of appropriate fabrics for seam efficiency and seam puckering.

References

1. Gersak J & Knez B (1991): Reduction in Thread Strength as a Cause of Loading in the Sewing Process, International Journal of Clothing Science & Technology, Vol 3, No. 4, pp 6-12.

2. Solinger J (1961): Apparel Manufacturing Analysis, New York.

3. Pavlinic D Z & Gersak J (2002): Design of the System for Prediction of Fabric Behaviour in Garment Manufacturing Process, International Journal of Clothing Science & Technology, Vol 6, No.1/2, pp 252-261.

4. Pavlinic D Z & Gersak J (2003): Investigation of the Relation Between Fabric Mechanical Properties and Behaviour, International Journal of Clothing Science & Technology, Vol 5, No. 3/4, pp 231-240.

5. Gersak J, et al (2006): Predicting Seam Appearance Quality, Textile Research Journal, Vol 76, No. 3, pp 235-242.

6. Behera B K & Sharma S (1998): Low Stress Behaviour and Sewability of Suiting and Shirting Fabrics, Indian Journal of Fibre and Textile Research, Vol 23, No. 4, pp 233-241.

7. Lam J K C & Postle, R (2004): Primary Hand Values Explained, Textile Asia, Vol 35 No. 9, pp 22-24.

8. Hunter L & Fan J (2004): Chapter 6: Fabric Properties Related to Clothing Appearance and Fit, Clothing Appearance and Fit, pp 89-113.

9. Gersak J (2002): A System for Prediction of Garment Appearance, Textile Asia, Vol 33, No. 4, pp 31-34.

10. Mori R, Haga, T & Takagishi T (1999): Mechanical Properties and Fabric Hand of Cotton Fabrics Subjected to Cellulose Treatment, Journal of the Fiber Science & Technology, Japan, Vol 55, No.10, pp 448.

Note: For detailed version of this article please refer the print version of The Indian Textile Journal November 2007 issue.

Sumit Mandal
Institute of Textiles & Clothing,
The Hong Kong Polytechnic University,
Kowloon, Hong Kong.

Dr Frency Ng
Institute of Textiles & Clothing,
The Hong Kong Polytechnic University,
Kowloon, Hong Kong.

Dr Patric Hui.
Institute of Textiles & Clothing,
The Hong Kong Polytechnic University,
Kowloon, Hong Kong.