Comparing the single yarn strength having different TPI and same count

This experiment was conducted to see how does twists per unit inch or TPI in a yarn effect its strength. For this purpose, other parameters like fiber type and count of yarn are kept constant.

The strength of a yarn greatly depends upon its twists per unit inch also called TPI. Yarn is simply a strand of fibers. Fibers are joined together to form a yarn. The binding force between the fibers is the twist given to the yarn at the time of spinning. The twist gave the fibers a binding force to make a yarn. This twist is very important for the yarn because it determines many characteristic properties of the yarn like air permeability, moisture absorption, feeling, dye ability and strength.This experiment is conducted to check the strength of yarn at different twists levels. The yarn twist has an optimum value by-passing which the strength of yarn starts decreasing. This is called the optimum twist. Yarn length also start deceasing by over-twisting.

Objectives

• To check the strength at different twists.
• To compare strength of different yarn having different twist.

Materials & Equipment

• 100% Cotton yarn package (TM = 3.8).
• 100% Cotton yarn package (Tm = 3.9).
• Uster TensoRapid Machine.

Procedure

• 100% cotton yarn package having TM value 3.8 was taken and loaded on the Uster TensoRapid.
• The yarn was passed through the passage in the machine.
• The machine was turned on and 10 readings were taken from that yarn.
• Another 100% cotton yarn package having TM value 3.9 was taken and loaded on the Uster TensoRapid.
• The yarn was passed through the passage in the machine.
• The machine was turned on and 10 readings were taken from this yarn.

Observations & Calculations

English Count (Ne) = 64.428/(lea weight in grams) = 20

Tex = 590.5 / (English Count)

1 Kg = 2.2 lbs.

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

TPI = TM √Count

Tenacity = no. of fibers×GPT×.70

Results

Strength of yarn having twist 16.99 = 11.05

Strength of yarn having twist 17.44 = 11.27

Discussion

Yarn having higher twist has fewer empty spaces in its structure, more compact and higher substance area utilization of yarn. Owing to these properties, high twist yarn has more tenacity as compared to low twist yarn. Being more compact, high twist yarn has harsher feel and provides less comfort as compared to its counterpart. Air permeability and moisture absorption of higher twist yarn is lower due to higher compactness.