Control of Fly Generation in Rotor Spun Polyester Cotton Blended

By Satyakam Srivastava, General Manager, RSWM Limited

Satyakam Srivastava General Manager, RSWM Limited

Satyakam Srivastava, D K Sharma, Neeraj Dwivedi, R K Shrimali, Sachin, 

Unit no.9, RSWM Ltd, Lodha Unit, Banswara, Rajasthan, India.

Abstract

The textile industry is known for its labour-intensive nature, and currently, there is a focus on certifications related to safety and health hazards for workers in this sector. The presence of fibre fly has a significant impact on yarn quality during fabric preparation and the final product. As the industry moves towards technical textiles, addressing this issue becomes crucial.

With the continuous drive for enhanced productivity in weaving and yarn processing, yarns are subjected to substantial stress and strains, leading to a decline in yarn quality and processing capabilities, especially during dyeing and other processes. Therefore, it is essential to effectively manage the generation of yarn fly and fluff during key processes such as warping, sizing, and weaving.

To address this concern, we conducted trials on Polyester cotton blended yarn produced through the Rotor spinning process, where fibres are bound to the yarn in core and sheath formation. Our trials focused on examining various parameters of the Rotor spinning process to assess the impact of these factors on fibre generation after the spinning stages.

Introduction

Fibre fly generation poses a significant challenge for the textile industry, impacting both health and product quality. The investigation of fibre fly generation during yarn unwinding processes has garnered considerable interest, especially following extensive research on yarn physical properties and studies on yarn hairiness. In recent decades, numerous studies have focused on theoretical yarn hairiness models, forming the basis for research into fibre fly generation during textile mill production.

As machine production speeds increase, fibre fly generation receives more attention due to heightened environmental impacts. It is now considered a more significant issue, driven by regulatory requirements mandating healthier and safer working environments in textile mills. Fibre fly generation not only compromises workplace health due to dust concentration but also affects product quality through potential contamination and disruptions such as yarn breakages and mechanical defects.

Historically, fibre fly generation was less severe because machine speeds were slower. However, with modern machines operating at higher speeds, the problem intensifies, as speed is a key factor influencing fibre fly generation. 

Practical observations revealed that yarns processed on high-speed warping machines and weaving looms with more than 400 PPM exhibit increased fibre fly during finishing processes. Lawrence and Mohamed’s research on weft knitting machines demonstrated fibre fly distribution along the thread line based on fibre length and percentage. They observed that most short fibres were removed during the unwinding phase. Most studies on fibre fly generation have utilised ring and open-end yarns in knitting and weaving processes.

Various parameters influence fibre fly during spinning processes, indicating that resolving the issue is complex and continuing. Textile machinery producers strive to mitigate fibre fly generation by adopting new technologies that minimise stress and friction on yarns during production. However, it remains a challenging task with various options.

Materials and Methods: 

Our raw material comprised 1.2 denier polyester from Reliance, with a standard length of 32mm. This polyester was blended with cotton in a 65% polyester to 35% cotton ratio. For yarn processing using the Rotor spinning method, we chose comber noil as the cotton component, which had a length of 17-18mm and a micronaire of 3.2-3.5.

We used a Trutzschler blow room setup, incorporating a TC 05 with 3 licker-in rollers in the Trutzschler card setup to produce a sliver. No spin finish was applied at the mixing stage. The sliver underwent further processing at the drawframe stages using the Trutzschler TD 08 and Rieter D50 in a single passage process.

The finished sliver was then fed into the Rieter R 37 semi-automatic rotor spinning machine, equipped with an automatic doffer for improved efficiency. The yarn was waxed during production to reduce fly generation. After yarn production, it was not subjected to preconditioning or vacuum steam conditioning. The produced yarn was tested under conditions designed to simulate customer environments.

Yarns were produced as under while comparisons were done,

Polyester 65%, Cotton 35%, Twist multiplier 4.3, opening roller OS, Standard nozzle “Spiral”, Rotor 33mm, False twist restrictor “V” Segment, Sliver hank 0.105, Waxed, Winding Tension below 0.98, Traverse length 148, angle of wind 36o,  on English count 14s, 16s, 20s

Test Method: 

We used a simple rewinding machine operating at a speed of 1000 m/min. Six cheeses, each weighing 1 kg, were processed simultaneously. After rewinding, we collected the fly accumulated at different parts of the machine to measure the grams of fly generated. Additionally, we analysed the fly’s composition to understand the impact of fibre.

Various trials were conducted, involving changes in the polyester manufacturing line, different draw frame models such as the Rieter D 50 and Trutzschler TD 03, adjustments to the speeds of opening rollers and rotors, nozzle changes, and other parameters.

Trial 1. Rewinding test confirmation by repeating samples and checking result variation.

Polyester Fibre Merge No	Count	Polyester Blend %	Hairyness	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester % in fly
Z2A40	16.00	65%	6.08	7200	136	18.3	74.50
Z2A40	16.00	65%	6.10	7200	136	15.5	78.80
Z2A40	16.00	65%	6.14	7200	136	19.5	76.80

Trial 2. Impact of process of Draw Frame of different models.

Draw frame Make	Polyester fibre Merge	Count	Polyester Blend %	Hairyness	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester % in fly
Trutzschler TD 03	Z2A40	20	40%	6.46	8200	105	20.0	57.81
Rieter D 50	Z2A40	20	40%	6.25	8200	105	22.6	58.60

Trial 3. Impact for Merge Z2A40 vs Z2A50 of polyester in different counts.

Polyester fibre Merge	Count	Polyester Blend %	Hairyness	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester % in fly
Z2A40	16	65%	6.32	6500	136	22.27	71.00
Z2F50	16	65%	6.67	6500	136	22.14	73.10
Z2A40	14	65%	6.67	6500	143	22.65	77.15
Z2F50	14	65%	6.93	6500	143	22.47	75.30

Trial 4. Impact of opening roller speed

Polyester fibre Merge No	Count	Polyester Blend%	Hairyness	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester % in fly
Z2F50	14	65%	6.62	7200	143	22.63	76.21
Z2F50	14	65%	6.71	6500	143	25.75	76.24
Z2F50	16	65%	6.21	7200	136	23.28	77.58
Z2F50	16	65%	6.39	6500	136	18.56	72.60

Trial 5. Impact of Torque Stop / Twist fix

False Twist element	Polyester fibre Merge No	Count	Polyester Blend%	Hairyness	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester % in fly
U ‘ Segment	Z2A40	16	65%	6.08	7200	136	18.25	74.50
V ‘ Segment	Z2A40	16	65%	6.20	7200	136	19.53	76.80
Twist Fix.	Z2A40	16	65%	6.56	7200	136	25.80	77.61

  Trial 6. Impact of rotor speed reduction

Polyester fibre Merge no.	Count	Polyester Blend%	Hairyness	Rotor Speed	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester % in fly
									Z2A50	16	65%	5.98	83000	7200	122	10.4	75.35
Z2A50	16	65%	6.23	93000	7200	136	30.3	73.86

Trial 7.  Impact of Navel / Nozzle

Drawoff nozzle	Polyester fibre Merge No	Count	Polyester Blend%	Hairyness	Opening roll speed	Machine Delivery speed	Fly-in gms generated per 6 kg of yarn unwound	Polyester content in fly
Spiral	Z2A40	20	65%	6.55	7200	105	25.44	79.19
S-Nano-6	Z2A40	20	65%	5.67	7200	105	3.53	81.83
Spiral	Z2A50	14	65%	6.62	7200	143	22.63	76.21
S-Nano-6	Z2A50	14	65%	5.43	7200	143	4.15	74.39
Spiral	Z2A50	16	65%	6.21	7200	136	23.28	77.58
S-Nano-6	Z2A50	16	65%	5.52	7200	136	1.74	75.98

Results and discussions 

Trial 1- We conducted repeated tests to ensure the consistency of the rewinding machine trial results, given that this is not a standard test procedure or testing machine. The tests showed no significant differences in the process results.

Trial 2 – We used the RIETER D50 draw frame with the lowest possible bottom guage and the Trutzschler TD08 draw frame with the highest possible bottom guage to ascertain the impact of fibre control via draw frame. There was no significant effect on yarn.

Trial 3 – Reliance produces polyester fibre from different manufacturing lines, each designated with a merge number to indicate variations. To account for this effect, trials were conducted using fibres from different lines to produce yarn. However, no significant effect was observed.

Trial 4 – To determine if the opening roller was damaging the fibre during spinbox processing, we reduced the opening roller speed by approximately 10%. The fly generation remained similar in both cases.

Trial 5 – To enhance fibre spinnability, open-end spinning uses a false twist generator, which also contributes to yarn roughness. We tested three different types of false twist generators:

• Twistfix:-Features three ridges to control maximum false twist, generating maximum roughness in the yarn and potentially leading to increased fly generation.
• “V” Segment:- Has a “V” groove to restrict false twists, providing more gentle control over yarn hairiness and resulting in a more even yarn structure.
• “U” Segment:- Contains a “U” groove to control false twist, offering very smooth operation with the least control over false twist, resulting in a smooth yarn finish.

 While there is a definite increase in fly generation when moving from the “U” segment to the “V” segment to the “Twist Fix,” the impact is not significant enough to address customer issues regarding fly levels.

Trial 6 – The impact of rotor speed reduction has been well-documented in various research studies, and our trials reflected similar findings. When we reduced the rotor speed by 10-11%, the fly levels significantly decreased from an unacceptable 30 grams to 10 grams.

Trial 7 – We used specially produced nozzles from RIETER, designated as “S-Nano-6,” which feature a smooth exterior with six mini grooves at the ceramic exit point. The ceramic in these nozzles is denser and smoother compared to other available nozzles, such as the “Spiral.” When considering all requisite parameters, the difference in fly generation was significant. The use of S-Nano-6 nozzles resulted in a reduction in fly generation by approximately 81-92%.

Conclusions: 

During the trials and testing, we observed that fly generation is directly proportional to yarn hairiness. Yarn hairiness is influenced by factors such as rotor diameter, rotor surface, nozzle/navel type, false twist controller, yarn linear density, and rotor speed. We also found that the opening roller speed has the least impact on yarn hairiness and, consequently, on fly generation in subsequent processes.

The nozzles/navels supplied by RIETER for the R 37 semi-automatic machine resulted in the lowest possible hairiness for polyester-cotton blended yarn with short cotton fibres. This also led to the predicted results at the customer end, with the lowest fly generation observed during subsequent warping and weaving stages.

References 

• Hanafy I.; Indian Text. J., Vol. 1 (1997)p. 16.
• Manich M., Barella A., Vigo J. P.; J. of Text. Inst., Vol. 72, No. 3 (1988) p. 121.

• Manich A. M., Barella A., Vigo J. P.; J. of Text. Inst., Vol. 72, No. 3 (1981) p. 131.

• Vila F., Pey A., Barella A.; J. of Text. Inst., Vol. 73, No. 2 (1982), p. 55.

• Barella A., Manich A. M.; J. of Text. Inst., Vol. 79, No. 2 (1988) p. 189.

• Kumar A., Ishtiaque S. M., Salhotra K. R.;Autex Res. J., Vol. 6 (2006) p. 3

1. 1. Majumdar A. Modeling of cotton yarn hairiness using adaptive neuro-fuzzy inference system, Indian Journal of Fibre and Textile Research 2010; 35(2): 121- 127. 
   2. Hasani H, Tabatabaei SA. Optimizing spinning variables to reduce the hairiness of rotor yarns produced from waste fibres collected from the ginning process, Fibres and Textiles in Eastern Europe 2011; 19, 3(86), 21-25. 
   3. Yuksekkaya ME. A Study of Fly Generation during Weft Knitting, Journal of Engineering Sciences 2000. 
   4. Yuksekkaya ME. Fibre fly generation of 100% cotton yarns during warp preparation Journal of the Textile Institute 2010; 101(3): 270-275. 
   5. Ghosh S, Bhowmick N. Contribution of cone-winding operation to the fibre-shedding behaviour of cotton yarn during knitting, Journal of the Textile Institute 2009; 100(1): 64-75. 
   6. Gonzalez RC, Woods RE. Digital Image Processing, Reading, Massachusetts: Addition Wesley, 1992. 

• Baykal P. D., Babaarslan O., Rizvan E.;FIBRES & TEXTILES in Eastern Europe,Vol. 15, No. 4 (63) 2007, pp. 46-49.

1. EP0445554A2 *1990-03-091991-09-11Rieter Ingolstadt Spinnereimaschinenbau AGYarn draw-off nozzle for an open-end spinning machine.