Development an Effective Quick Fabric Relaxation Machine

Transcription

1 Development an Effective Quick Fabric Relaxation Machine Dr. T S S Jayawardana #, Prof. E A S K Fernando #2, G H D Wijesena #3 Prof. Rohana Kuruppu *4 #, 2 Senior Lecturer, Dept. of Textile & Clothing Technology, University of Moratuwa, Sri Lanka #3 Chief Technical Officer, Dept. of Textile & Clothing Technology, University of Moratuwa, Sri Lanka * 4 CEO, Brandix College of Clothing Technology, Ratmalana, Sri Lanka Abstract Fabric relaxation is an essential operation in the process of garment manufacturing and without it, is not possible to obtain the dimensional stability of the final products. Fabric relaxation is characterized by the shrinkage of the fabric and the shrinkage percentage is high for knitted fabrics especially containing elastane. There are different methods available for fabric relaxation such as compressive relaxation, heat set relaxation and sponging relaxation. However, they are prohibitively in use due to their high cost or the excessively high time taken for the process. Hence the bale relaxation is popular in used for effective fabric relaxation but the conditioning time in bale relaxation is varied from fabric to fabric and buyer s recommendation. Time taken for fabric relaxation is a key problem and as a solution high speed fabric relaxation machines were developed but they have serious limitations as it cannot be effectively used for fabrics with higher shrinkage levels and especially in knitted fabrics with elastane content. Hence a new fabric relaxation machine was designed and a prototype of it was developed. It composed of fabric unwinding unit, fabric rewinding unit without creating additional strain in the fabric, and fabric relaxation with sinusoidal vibration followed by the air floatation unit. The effectiveness of the prototype of the fabric relaxation machine was validated with experiments carried out with two fabric types of knitted fabrics containing different elastane content and gsm values. It was compared with the popular C-Tex machine used in the industry and showed that a better relaxation levels could be achieved with the developed prototype. Hence the developed machine has strong industrial implications. However, the speed of operation is essentially improved and the consumption of air in the air floatation unit needs to be optimized in commercialization of the product. Keywords Fabric relaxation, knitted fabric, air floatation zone, vibration I. INTRODUCTION Fabrics are subjected to heat in the processes of removing moisture in dyeing and finishing. When the fabrics come into normal condition such as ambient temperature and atmospheric pressure, the fabric absorbs moisture from the atmosphere and regains its original nature and it is called fabric relaxation. In other words, fibres and yarns which are under strain in fabric formation followed by finishing processes, comes into natural condition where the internal forces are in equilibrium state. The ultimate relaxed state is the "fully relaxed" state, in which the loops are in an equilibrium state for knitted fabrics and in without strain for woven fabrics. Shrinkage is induced by the relaxation of strains present in a fabric when the fabric becomes into relaxed form which is free from strain in the fabric. Relaxed dimensions are defined as the state at which a fabric is fully relaxed and will not shrink further as a result of washing and tumble drying. Relaxed dimensions are also referred to as the reference state [3].. Current practices in the industry If the dimension is become stabilized before cutting, the chance of remaining strain in garments is minimum unless there is no mechanical forces apply on fabric panels in the process of sewing to yield some level of tension. Fabric relaxation before cutting panels of a garment is a key to achieve the dimensional stability of produced garments. So before cutting, fabrics must be converted in to fully relax stable state by undergoing it through any suitable fabric relaxation method. Fabric relaxation prior to cutting is generally performed by keeping the fabric under standard atmospheric condition in opened and spread under tensionless arrangement termed as conditioning over a predetermined time period. This time is varied from fabric to fabric as well as buyer s recommendation subjected to a minimum relaxation time period of twelve hours and more effective period of twenty four hours. The fabric is unwounded from the roles and lays the fabric in a zig-zag way to obtain tension free fabric. This method is called bale fabric relaxation. As this method is rather time consuming, certain fabric relaxation machines are used, but not effective for fabrics with higher shrinkage. Many advanced relaxation regimes are also in practice specifically based on the type of the fabric. The compressive relaxation for woven cotton, tabular knit cotton, linen, rayon etc., heat set relaxation is for thermoplastic fibres such as nylon, polyester, acrylic etc, resin treated relaxation is for rayon as well as for ISSN: Page 3

2 cotton and sponging relaxation is for woolen and many worsted fabrics. Sponging relaxation can be applied for a large range of fabrics in which wetting the fabric with water or steam and allowing the material to dry slowly in relaxed tensionless state. This method is much slower than conditioning fabrics over 24 hours for relaxation which is much popular in use, but much effective in reaching the fully relaxed stage. All these four specific methods described above are either too slow in process or prohibitively expensive to produce cost effective garment to meet the competitive edge in the market. Knitted fabrics are much more susceptible for shrinkage due to relaxation as compared to woven fabrics due to its natural construction with loops. Woven fabrics are much stable than knitted fabrics due to the perpendicularly interlaced yarn structure and woven fabrics cannot attain %-5% level of extensibility and recovery from extension. For certain types of knitted fabrics, relaxation in conditioned environment under tension free condition may not be effective enough to achieve dimensional stability and hence relaxation is done in two stages namely taking out from knitting and before laying the fabrics for cutting. Before sending fabrics to the cutting section, the fabric samples obtained from the rolls are subjected to test for dimensional stability and according to the test results the method of relaxation are determined. Residual shrinkage test, heat shrinkage test and steam shrinkage test are the main tests which are used in the industry to determine the relaxation procedure before bulk fabric cutting. If the shrinkage test result is less than 2 percent no relation is done. If the level of shrinkage in the test results lies between 2 percent and 4 percent, machine relaxation is recommended whereas for fabrics with shrinkage more than 4 percent, bale relaxation is used. In machine relaxation with C-tex machine, fabric is unwound from its roll using positive feeding technique to avoid creating additional tension in unwinding process and feeding at the successive stage is slightly make slower at initial stage to create a tension free sag. Subsequently fabric is fed over an air floatation zone for fast relaxation of the fabric. Though the output of the machine is high as 6m/s, fabric could not be relaxed adequately at that speed. So this method could not be applied for fabrics from which large panels are cut or in case of sportswear manufacturing. Hence standard relaxation grid is formed after doing experiments on relaxation with different types of fabrics and also on the past data captured by the research and development center. Test cutting and approval procedure is adopted for the fabrics which are not in standard relaxation grid. In this method, small amount of fabric is cut after trial relaxation method, sewed in sample room and compared with the approved sample. Sewing allowance and other measurements are checked and if everything is ok then the approval is given to proceed with the trial relaxation method before bulk production..2 Knitted fabric relaxation methods In the plethora of literature on fabric relaxation, knitted fabrics especially containing elastane were mainly focused as its relaxation was crucial in dimensional stability on the garment manufactured. Munden [7] defined two fabric relaxation methods namely dry and wet processes. In the dry relaxation knitted fabrics were exposed to air for certain period while in the wet relaxation knitted fabrics were immersed in warm water. Knapton et.al. [] applied mechanical (laundering and tumble drying cycles) and chemical (fabric mercerisation without tension) relaxation treatments to knitted fabrics. It was shown that either treatment contributes to considerable dimensional stability leading to fully relaxed condition of the fabric..3 Shrinkage and its effects Fabric relaxation is characterized by a change in the dimensions of a fabric and it is technically referred to as shrinkage. Shrinkage can be further divided in to two categories as construction shrinkage and processing shrinkage. Construction shrinkage is defined as the amount of dimensional change in a fabric based solely on the construction variables used to create the fabric. It is measured after fabrication but before subsequent processes. Dyeing and finishing stages create processing shrinkage after fabric formation. The dimensional change may be in a positive (growth) or negative (shrinkage) in lengthwise, widthwise, and thickness. Those shrinkage parameters are related in changing fabric dimensions, seam puckering, torquing, and overall garment fit. Shrinkage can be further defined as a dimensional change in a fabric or garment caused by an application of a force, energy, or a change in environment that either allows the goods to relax or forces the fabric to move in a given direction. Strohle et.al. []. introduced a new method for the relaxation of knitwear containing elastane. The grey fabric is saturated in an impregnating unit with soda, suitable wetting agents and emulsifiers and placed on a roller bed. Knitted fabrics tend to change dimensions in width and length after being taken off the machine, even without yarn shrinkage, indicating a change of loop shape rather than of loop length. During knitting, the loop structure is subjected to a tension of approximately 5-25 grams per needle from the sources in case of the takedown mechanism and also in fabric inspection machines, the width stretched. Theoretically knitted loops move towards a threedimensional configuration of minimum energy as forces applied to fabric during production process and all those are allowed to be dissipated [2]. ISSN: Page 3

3 .4 Key developments of fabric relaxation machines.4.. Benninger's all in one plant fabrics with higher shrinkage levels precisely more than 4 percent. Fig. : Benninger's all in one plant for relaxation of knitwear [] Fig. shows the Benninger's all in one plant [] for relaxation of knitwear and the concept behind this machine is to process steps of impregnation, dwelling and washing out in a very small space. After unwinding the fabric from the roll, it is sent through an inspection zone, then it is treated with steam of 4-6 Kg/cm2pressure for relaxation. However the main objective of this machine is not the relaxation of fabrics and it cannot also be used for different kinds of fabrics Fabric relaxation machine of Voisin et.al Fig. 2 - Prototype invented by Voisin [2] Another method for relaxation machine was invented by Voisin et.al. [2] and humidity, heat and agitation of the fabric were used as means of relaxation. The fabric carried by a conveyer and is dropped onto another surface at a particular speed of about 2 meters/minute and approximately takes 45 minutes for a single fabric sample C-Tex machine Figure 3 shows C-Tex fabric relaxation machine and it is widely used in the industry. Lazy loop and air floatation zone are two fabric relaxation techniques used in the machine. Initially fabric is unwound into a photocell controlled lazy loop, which allows returning the fabric to its natural state. In that air floatation zone a pressurized supply air is applied perpendicularly to the fabric. Subsequently fabric is rewound on to a roll with positive feed winding mechanism. However, it was noted that machine cannot be effectively used to relax the Fig. 3 - C-Tex fabric relaxation machine [].5 Modeling of fabric properties A major advance in this field occurred when Doyle Munden [7] reported that for an extremely wide range of relaxed plain-knit fabrics, the fabric dimensions (width and length) are completely determined by the knitted loop length and it is characterized by the following equations () (2) or (3) (4) (5) Where cpi and wpi are courses and wales per unit length respectively and l is length of the fabric.,, are fabric dimensional parameters and the numerical values of them depend on the actual configuration of the knitted loop. is described as the loop shape factor which is the ratio of width of the loop to the length of the loop. Hamid, Dariush and Mohammad [9] shown that in the different relaxation methods yield different values and value increases when the fabric become fully relaxed with minimum energy. So these parameters can be used to analyze the effectiveness of different relaxation methods. Semnani et.al. [3] proposed an ideal model for plain weft-knitted fabric using classical mathematical curves based on the elastic rod model [4]. As per this model, in a fully relaxed state, the loop takes a specific shape with loop shape factor approximately.4. In the theoretical model, value of the fabric constant dimensional parameter yielded as = which is higher than fully relaxed plain knitted fabrics as reported by previous researchers who concluded that a more advanced relaxation method should be used in finishing treatment for weft-knitted fabrics to make the stitch shape closer to the ideal and to raise the practical -value. Knapton [] has shown that dimensional stability in cotton plain-jersey fabrics can be attained by either mechanical relaxation techniques or chemical treatments, and that k-values are not entirely independent of the fabric tightness. [5]. Ultrasonic ISSN: Page 32

4 waves were employed as a new mechanical relaxation method to achieve maximum fabric shrinkage [6]. By using longitudinal ultrasonic relaxation process on cotton plain knitted fabrics, they could reach a -value equal to 24.87, which is higher than with other relaxation methods, but still smaller than the theoretical Ks-value. Subsequently Sanjari et. Al. [5] ultrasonic waves with a frequency of 35 khz and intensity of 9 W/cm2 was used for fabric relaxation, together with minutes relaxation in water of 7 C. Afterwards the samples were dried for 24 hours on a flat surface at room conditions. This experiment could reach dimensional parameter value as high as 24.5 for plain knitted fabric knitted with polyester cotton (65/35) of yarn count 3 Tex and it was much higher than other relaxation methods tried out. Though an ample number of modern, advanced and complex relaxation methods found in the literature, bale relaxation method is still effectively used in the garment industry due to its cost effectiveness and no need of technical investment. However, this method needs an ample space while one day lead-time exists prior to bulk cutting. Fabric relaxation machines effectively addressed the short comings of the bale relaxation method, but unable to bring the fabrics to fully relaxed condition when the shrinkage level more than 4 percent. This creates a niche to develop a new fabric relaxation machine which is capable of relaxing fabrics with higher shrinkage levels and not taking much time for relaxation as does in bale relaxation. This article describes an attempt made to address this gap by developing a new fabric relaxation machine consists of vibration unit and air floatation unit both supports fabric relaxation in synergy. Despite more scientific measures such as loop shape factors, dimensional parameters, irregularity indices (Radon and actual) were defined, industry still relies on the test methods such as residual shrinkage test, heat shrinkage test and steam shrinkage test. Hence we evaluate the effectiveness of the machine using the above tests. 2. DESIGN AND DEVELOPMENT OF FABRIC RELAXATION MACHINE It is imperative to determine the fabric relaxation methods to be used before designing the proposed fabric relaxation machine. The specifications such as the speed of the machine, level of relaxation and shrinkage level of the input are critical and essential in determining the fabric relaxations to be deployed. Further, from the literature, it was well establish the fact that the effective relaxation method is also highly dependent on the type of fabric also. With synthetic fabrics like % polyester, mostly relaxation process is almost unnecessary as the visible shrinkage level is negligible. However, fabrics containing elastane, shrinkage scenario is different as with the increment of the elastane percentage, residual shrinkage level is also become dominant. 2. Conceptual design Though the bale relaxation is an effective type of relaxation, it takes a long time and causing for a higher lead-time. Though it is non-value added operation but it cannot be omitted with most of knitted structures. As the industry is more competitive and it is essential to make the production process more profitable by diminishing the time for non-value adding processes. For certain fabrics with the elastane content, bale relaxation is a must, but keeping fabrics for such a long time to relax is a waste of time in the industry. Hence the proposed fabric relaxation machine is developed to reduce the relaxation time of knitted fabrics with elastane and especially in sportswear with large panels to cut from the fabric where C-Tex machine is failed in effective fabric relaxation. As the chemical relaxation does not support the agile concept of relaxation and it was not under consideration as a means of fabric relaxation and only mechanical means were in the solution space of relaxing fabrics in the proposed machine. After a careful analysis of the contributory impact of different types of mechanical fabric relaxation methods as per the data found on literature, it was decided to instrument mechanical vibration pattern and an air floatation zone as fabric relaxation methods. Most appropriate type of mechanical vibration pattern was identified as sinusoidal as it is smooth by its nature due to the fact that if the displacement is a sine wave, then the velocity and acceleration will be scaled cosine and negative sine waves respectively. Further, it can be conveniently generated with a slider crank mechanism and its frequency can be adjusted by varying the rotational speed of the motor which drives the crankshaft. Further, adjustable piston rod lengths can be instrumental in varying the amplitude of vibration depending on the fabric type, while the pneumatic pressure can be adjusted by means of a pressure regulating valve to cater for different gsm values of the fabric. To facilitate further relaxation, an air flotation zone was deployed after mechanical vibration zone. Unwinding and rewinding of fabrics could be done by placing the fabric roller on two rotating rollers of same speed synchronized with machine speed to avoid additional tension to the fabric. 2.2 Design and develop a prototype Fig. 4: Inverted plan of the fabricrelaxation machine prototype ISSN: Page 33

5 Fig. 4 shows the CAD deign of the inverted plan of the fabric relaxation machine prototype. Left rollers are used to unwinding the fabric while right two rollers are for winding the relaxed fabric into a roller without creating an additional tension due to winding. These all rollers and the vibration unit are driven by timing belts and propelled a motor to synchronization of speeds. In order to minimize the complexity of the prototype, lengths of piston rods kept constant. Four pistons provide a vertical reciprocating movement to the fabric across its width so that the loops of the fabric can effectively come into equilibrium position minimizing the stored energy. Increasing the number of pistons can make a further effective vibration over higher fabric width. The vibration effect in the lengthwise direction is dominant up to the moderate speed of the machine but essential to deploy another sit of pistons to provide an effective lengthwise relation through vibration at higher operational speeds. a b Fig.5: Air floatation zone After the mechanical vibration zone fabric enters in to an air floatation zone where compressed air is blown perpendicular to fabric such that fabric glides on an airbed to facilitate convenient relaxation. The inter-nozzle separation in widthwise (a) and lengthwise (b) are set to 6cm, 5cm to achieve the trade off between the cost and effective relaxation by trial and error method. A motor of 625rpm was used as the prime mover of the system and it is possible to achieve 75m/min be achieved with prototype. conditioning in the standard environment for 24 hours and 48 hours respectively. In determining the lengthwise and width wise shrinkage levels the following formulae were used. (6) (7) The prototype of fabric relaxation machine was operated at one tenth of its maximum limit 75m/min in all the experiments and used for relaxing knitted fabrics. Fabric samples of two fabric types were under testing and the details of the fabric types are given in Table. Fabric Structure Composition GSM Fabric Single Cotton 94% 45 Jersey Spandex 6% Fabric 2 Single Jersey Cotton 87.5% Spandex 2.5% 8 Table - Specifications of fabric roles 2 fabric roles from each fabric type were tested on the prototype of fabric relaxation machine developed. In testing the samples, only vibration effect, only air flotation effect with the pressure of 4 bars and the combination of both effects were experimented and the results were plotted in the same graph. The relaxed sampled both relaxation effects on the fabric relaxation machine prototype were further subjected to bail relaxation to identify the level of relaxation and it is also plotted to demonstrate the effectiveness of the prototype developed. 4. RESULTS AND DISCUSSION Fig. 6 and Fig. 7 show the level of shrinkage for cotton: 9.68% Spandex: 8.32% fabric with 8gsm after 24 hours and 48 hours respectively 3. METHODOLOGY As 24 hour and 48 hour relaxation time is currently in practiced for cotton/spandex fabric, it was decided to investigate the effect on relaxation time. Hence 8 test samples were under testing from cotton: 9.68% Spandex: 8.32% fabric with 8gsm which was wound to fabric rolls at the weaving laboratory. Due to limitation of the availability of fabrics, one meter length samples were cut from each fabric role and the level of shrinkage in lengthwise and width wise were measured after ISSN: Page 34

6 S h r i n k a g e ( % ) hrs % 48hrs % Fig.6: Percentage lengthwise shrinkage in bale relaxation after 24 and 48 hours S h r i n k a g e ( % ) hrs % 24hrs % - Fig.7: Percentage widthwise shrinkage in bale relaxation after 24 and 48 hours Residual Shrinkage (%) Structure Composition Length Direction Width Direction Single Jersey 92% Poly, 8% Spandex.5.5 Single Jersey 85% Poly, 5% Spandex 2.5 Single Jersey 74% Nylon, 26% Spandex.5.5 Single Jersey 79% Nylon, 2% Spandex 2.5 Single Jersey 54% Cotton, 2% Poly, 2% Viscose, 5% Spandex Single Jersey 53% Cotton, 35% Modal, 2% Spandex * Rib % Cotton.5 Table 2: Residual shrinkage results of C-Tex machine for different fabrics types ISSN: Page 35

7 Percentage Shrinkage Percentage Shrinkage Percentage shrinkage Percentage Shrinkage International Journal of Engineering Trends and Technology (IJETT) Volume-42 Number-6 - December Vibration only Air only Vibration + air Fig. 8: Fabric relaxation on machine-shrinkage level for fabric type only with vibration, air and combinational effect only air only vibration vibration+air Fig. 9: Fabric relaxation on machine-shrinkage level for fabric type 2 only with vibration, air and combinational effect after 24 hours after 48 hours Fig. : Shrinkage levels of bailing after machine relaxation for fabric type after 24 hours after 48 hours Fig. : Shrinkage levels of bailing after machine relaxation for fabric type 2 ISSN: Page 36

8 The test was repeated with the same fabric with different gsm values and it was noted that as the gsm is increased, percentage shrinkage level reduces. Further, results shown in Figure.6 and Figure.7 revealed that 24 hour bale relaxation is not adequate as a significant marginal shrinkage level is noted in lengthwise even after 24 hours. In order to substantiate the facts presented in section.3, different types of fabrics were relaxed on a C-Tex machine and the residual shrinkage results are presented in Table 2. According to the results indicated in Table, percentage of relaxation obtained with C-Tex fabric relaxation machine lies between 2% generally where the maximum level of shrinkage of these fabrics lies above 6 percent when reaching fully relaxed state. Due to that fact C-Tex relaxation is mostly used in the industry for intimate wear products but not for sportswear manufacturing. The shrinkage level on prototype fabric relaxation machine for test fabrics type and 2 are given in fig 8 and Fig.9 respectively. On each graph, the effect of compressed air, effect of vibration and combinational effect of both are separately indicated. On both fabric types, the effect of vibration is more dominant over the effect of compressed air on fabric relaxation especially in the case of fabric type 2 which has a higher gsm value. As the gsm value of the fabric is not high, effect of vibration is highly fluctuated from sample to sample. Inter-sample variation in percentage shrinkage becomes less significant in case of fabrics with higher gsm values as the floatation effect may be lesser under constant air pressure of 4 bars. Further it is noted that the shrinkage levels get minimized with the increment of gsm value of the fabric but is not very much exemplary in comparison of fabric type and 2 because the elastane percentage is also increased in the fabric sample with higher gsm. When comparing with the relaxation levels achieved by C-Tex machine as in Table, the prototype reveals the achievement of better relaxation levels, however at much lower speed of 2/7 of C-Tex machine speed. The prototype is a simple device fabricated just to test the effectiveness of the combination effect of vibration and air floatation zone, no much provision to adjust the parameter of the device. However, it was noted that there is a significant drop in the relaxed fabric quality when the output of the machine is increased beyond moderate speed. The relaxed fabric roles on the prototype of the fabric relaxation machine were subjected to bale relaxation and the further shrinkage levels were recorded after 24 hours and 48 hours. The results corresponding to fabric types and 2 are given in Fig. and Fig. respectively. Percentage shrinkage level in bale relaxation followed by machine relaxation for fabric type 2 is less than for the all samples tested and few samples exceeded percent but less than.5 percent for fabric type 2 which has a lower gsm value. The remaining level of shrinkage after relaxation on prototype developed is less than 2 percent, it can be used for even sportswear manufacturing without any further relaxation. Even more than 4 percent and 2 percent shrinkage could be achieved with the developed prototype machine for fabric types and 2, its effectiveness in fabric relaxation is validated. However, speed of the machine is essential to be improved significantly for the commercial use and a mathematical model of the air floatation unit be developed in order to optimize for the compressed air consumption, though trial and method was used to come up with a working model in developing the prototype of the fabric relaxation machine. 5. CONCLUSION Relaxation is an irreversible change in fabric dimensions (shrinkage or expansion) that occurs when a fabric is released from the forces applied in lengthwise and widthwise. Bale relaxation is used as an effective method of fabric relaxation in the industry however the time taken for relaxing fabrics, generally 24 hours is a major concern. Though this is not a value adding process, it cannot be omitted from the process because of the dimensional changes which can be occurred after cutting or stitching in the garments and even it may cause to reject the entire lot. The alternative high speed fabric relaxation machines have serious limitations as it cannot be effectively used for fabrics with higher shrinkage levels and especially in knitted fabrics with elastane content. To address this burning need, a new fabric relaxation machine was designed and a prototype of it was developed. It composed of fabric unwinding unit, fabric rewinding unit without creating additional strain in the fabric, and fabric relaxation with sinusoidal vibration followed by the air floatation unit. The effectiveness of the prototype of the fabric relaxation machine was validated with experiments carried out with two fabric types of knitted fabrics containing different elastane content and gsm values. In comparison with the C-Tex machine which is used for relaxing limited number of knitted fabrics, a better relaxation levels with shrinkage levels up to 3 to 4 percent could be achieved with the developed prototype while it was limited to 2 percent in C-Tex machine. Hence the developed machine has strong industrial implications. However, the speed of operation is essentially be improved and the consumption of air in the air floatation unit needs to be optimized in ISSN: Page 37

9 converting the prototype of the fabric relaxation machine in to a commercial industrial product. ACKNOWLEDGMENT Authors gratefully acknowledge H B H Buddika, S M Kavirathna, H R P Weerasinghe in carrying out the experiment trials and for the development of prototype. Further, the acknowledgment is extended to Mr. H M R P B Herath, Technical Officer of the Weaving Laboratory and Mr. Suminda Senarathna, Laboratory Attendant of the weaving lab for the technical support given in the construction of the prototype of the fabric relaxation machine. REFERENCES [] J. J. F. Knapton, E. V. Truter, A. K. M. A. Aziz; J. Text. Inst., Vol. 66, No. 2, 975, pp [2] David J Spencer, Knitting Technology, Elsevier, 24, pp. 25. [3] D. Semnani, M. Latifi, S. Hamzeh, A. A. A. Jeddi; J. Text. Inst., Vol. 94, 23, pp [4] G. A. V. Leaf; J. Models of the plain-knitted loop, Appl. Phys., Vol. 9, 958, pp [5] H. R. Sanjari, D. Semnani, M. Sheikhzadeh; Investigating the Performance of Various Relaxation Processes on the Surface Regularity and Dimensional Properties of Plain Knitted Fabrics Using the Image Processing Technique, FIBRES & TEXTILES in Eastern Europe 2, Vol. 9, No. 2 (85) pp [6] A. A. A. Jeddi, V. Mohammadi, H. Rahimzadeh, F. Honarvar; Fibres and Polymers., Vol. 8, 27 pp [7] D. L. Munden, "The geometry and dimensional properties of plain-knit fabrics", Journal of The Textile Institute, 5, 959, [8] ResearchGate publication, New process for the relaxation of knitwear containing elastane, _process_for_the_relaxation_of_knitwear_containing_elast ane. [9] R. S. Hamid, S. Dariush, S. Mohammad, Investigating the Performance of Various Relaxation Processes on the Surface Regularity and Dimensional Properties of Plain Knitted Fabrics Using the Image Processing Technique, FIBRES & TEXTILES in Eastern Europe 2, Vol. 9, No. 2 (85) pp [Online] Available; [] J. Ströhle /Benninger AG, CH- 924 Uzwil / Switzerland, New process for the relaxation of knitwear containing elastane (spandex) [Online] Available; _Knitwear_English_8 5.pdf [] C-TEX RM Fabric Relaxing & Measuring Machine [Online] Available [2] E. Voisin, P. Aujard, Method and device for relaxing knitted fabric U.S. Patent No A, Sep 27, 988 [3] M. A. Sheshir, Dept. of Textile Engineering, Southeast University, Shrinkage presentation [Online] Available ISSN: Page 38