Compare the tensile strength of Ring spun and Rotor spun yarns having same count (20s).

Abstract:

In this experiment different properties of ring and rotor spun yarns were compared. The properties studied are breaking work, breaking force, tenacity and elongation of ring and rotor yarns. The yarns used for this experiment both have 10s count. The results showed that the ring spun yarns have good properties then the rotor spun yarns.

Introduction:

Ring spinning system is the most common spinning system used in the Pakistan textile industry. This spinning system produces yarns of good characteristics, but the system is a slow process for the production of yarn. The production rate of ring frame is about 15,000-25,000 rpm. In ring spinning many drawing frames are also used along with carding, combing and roving frames. This also makes the production system slow. But the control of yarn being produced is good, its twist and count can be easily controlled.

Contrary to ring spinning process the rotor spinning process is the very fast method of yarn production system. The average speed of rotor frame is 130,000-145,000 rpm, which is far more than that of ring frame. Moreover no combing or roving frames are used in this spinning process with also eliminates the use of more than one draw frames. But the control over yarn is far less than that of in ring system. The twist and count might be varied in the rotor spinning process and we could also get woody pattern on yarn, which will be far more visible in the dyeing of yarn.

The yarns are tested according to ASTM Standard – D2256. It specifies the test conditions for determining the tensile properties of yarns using the single-strand method.

Objectives:

• To compare tensile strength of ring and rotor spun yarns.
• To compare elongation at break % of ring and rotor spun yarns.
• To test the materials before the fabric manufacturing process.

Materials & Equipment:

• 100% Cotton ring spun yarn.
• 100% Cotton rotor spun yarn.
• Uster TensoRapid Machine.

Procedure:

• The packages of 10s count ring and rotor spun yarns were taken.
• Ne count of these yarns was converted to Tex and pre-tension was determined for these both yarns.
• The Uster TensoRapid machine uses a software system for inserting the test parameters to the machine, using them the test parameters were entered in the machine.
• To determine tensile strength and elongation at break, packages of ring and rotor spun yarns were placed on the Uster TensoRapid.
• The yarns were clamped in the appropriate grips of the Uster TensoRapid machine and extended at constant rate until failure occurs.
• 10 readings were taken for each ring and rotor spun yarns.
• The test results were used to determine the breaking tenacity, breaking force, breaking work and elongation at break of the material.

Observations & Calculations:

Formula Used

Count = Ne = 10s

Tex = 590.5 / (English Count) = 59.05

Co-efficient of Variation = (S.D) / X̅ ×100

Pre-Tension = 0.5 × 59.05 = 29.525

Breaking Tenacity = (Breaking Force) / (linear Density) = cN/Tex

Tenacity = cN/Tex of yarn ×.70 (In case of ring spun yarns)

Tenacity = cN/Tex of yarn×.55 (In case of rotor spun yarns)

Elongation %age of yarn = ∈p = (E×R×100) / (C × Lg)

E = distance along the zero force axis from the point corresponding to the point where the force-elongation curve passes the pre-tension force to a point of corresponding force, mm (in.)

R = testing speed rate, mm/min (in/min),

C = recording chart speed, mm/min (in/min), and

Lg = nominal gage length, mm (in.)

100% Cotton Ring Spun Yarn

Sr. #	Time (sec)	Breaking Work (cN.cm)	Breaking Force (cN)	Tenacity (cN/Tex)	Elong. (%)
1	0.40	1066	754.8	12.78	5.64
2	0.42	1024	735.6	12.46	5.79
3	0.49	1574	942.6	15.96	6.93
4	0.39	979	700.4	11.86	5.49
5	0.38	957	691.7	11.71	5.47
6	0.42	1196	796.7	13.49	5.98
7	0.47	1424	896,7	15.19	6.72
8	0.46	1252	820.9	13.90	6.44
9	0.46	1321	849.2	14.38	6.53
10	0.36	870	678.9	11.50	5.08
Mean Values	-	1166	786.8	13.32	6.01
Coefficient of Variation %	-	19.40	11.47	11.47	10.27

 

100% Cotton Rotor Spun Yarn

Sr. #	Time (sec)	Breaking Work (cN.cm)	Breaking Force (cN)	Tenacity (cN/Tex)	Elong. (%)
1	0.42	1118	676.3	11.45	5.94
2	0.44	1215	728.3	12.33	6.10
3	0.44	1265	724.6	12.27	6.16
4	0.40	962.0	628.4	10.64	5.51
5	0.28	502.0	447.9	7.85	3.97
6	0.42	982.7	618.6	10.48	5.81
7	0.48	1435	767.2	12.99	6.80
8	0.42	1094	660.3	11.18	5.87
9	0.40	490.0	594.7	10.07	5.58
10	0.44	1237	697.7	11.81	6.28
Mean Values	-	1075	654.4	11.08	5.80
Coefficient of Variation %	-	23.64	13.82	13.28	12.80

 

Results & Discussion:

Tensile Strength

Tensile Strength of Ring Spun Yarns = 13.32 cN/Tex

Tensile Strength of Rotor Spun Yarns = 11.08 cN/Tex

The results from the Uster TensoRapid shows us that the tensile strength of the ring spun yarn is better than that of rotor spun yarns. This is believed due to the removal of short fibers during the ring spinning process and hence only long fibers remains, which can twist together with good fiber to fiber friction and hence the overall strength of the fiber is increased. But in case of rotor spinning short fibers are not removed efficiently which causes the yarn to lose its strength. Moreover the ring spun yarns are re-winded to remove any thick, thin places and neps.

Elongation at Break

Elongation %age for Ring spun yarns = 6.01

Elongation %age for Rotor spun yarns = 5.80

The elongation of a yarn has an influence on the manufacturing process and the products made. It provides an indication of the likely stretch behavior of garment areas such as knees, elbows, or other points of stress. It also provides design criteria for stretch behavior of yarns or cords used as reinforcement for items such as plastic products, hose, and tires.

The results showed that the elongation of the ring spun yarns is more than that of the rotor spun yarns. This could be due to the factor that the ring spun yarns has less thin places in them and IPI of ring spun yarns is low than the rotor spun yarns. More over short fibers were also removed in the ring spinning process hence long fibers could contributes in the yarn elongation properties. But this is not a fixed property that ring spun yarns has always more elongation than rotor. If the rotor spun yarns have more thick places or neps in them they could elongate more.

Conclusion:

This experiments showed that the ring spinning system provides us yarns with good properties than the yarn produced by rotor spinning process. But more energy, cost, labour, and time is required in the manufacturing process of ring spun yarns.