Calculation of Twist, Twist Constant of Ring Frame

Last Updated on 04/03/2021

Name of the experiment:
Calculation of twist, twist constant of the ring frame.

Twist is inserted to the staple yarn to hold the constituent fibers together, thus giving enough strength to the yarn and also producing a continuous length of yarn. Twist is imparted to staple yarns to induce lateral forces. Friction created by these forces acts to control fiber slippage in a strand under tension. The degree of twist given to fibrous strand in the ring spinning process is dependent on the rate of revolving the strand and the rate at which the strand is delivered from the drafting rollers:

Twist Per Inch (TPI) = Spindle speed / Front roller delivery

TPI = TM x  √Count in Ne

When the twist increases, the yarn strength increases up to a certain level, beyond which the increase in twist actually decreases the strength of staple yarn (Figure 1). Fine yarns require long staple fibers and high twist. Coarse yarns can be produced with short fibers and low twist. Twist multiplier for cotton usually ranges between 3 and 5. The twist of weft yarns is approximately 4%–5% below the twist of warp yarns. The twist of hosiery yarns is approximately 12%–15% below the twist of warp yarns.

Effect of twist level on yarn tenacity
Figure 1: Effect of twist level on yarn tenacity

Spinning is the process of producing continuous twisted strands (yarn) of a desired size from fibrous materials. Spinning can be categorized based on staple length as long staple spinning and short staple spinning.

Ring and traveler are the dominant elements in the ring spinning process. Ring and traveler play a crucial role in the twisting process. The correct selection of ring and traveler has a predominant influence on the spinning performance.

In ring spinning, the energy to drive the twisting mechanism is derived from the bobbin, but the level of twist is controlled by the traveler. Each revolution of the traveler inserts one turn of twist into the yarn.


  1. To find out twist per inch of the ring frame.
  2. To find out twist constant of the ring frame.


  • Front roller diameter =  1″
  • Tin cylinder diameter =  10″
  • Whrave diameter = 1.125″
  • Twist change pinion = 48T

Gearing diagram:

gearing diagram for calculating twist and twist constant of ring frame
Fig: Gearing diagram for calculating twist and twist constant of ring frame


1) TPI = 1 x (98/48) x (86/42) x (46/5526) x (10”/1.125”) x (1/(π x 1”)) = 20.93 » 21

2) Twist constant = TCP x TPI = 48 x 21 = 1008


1) TPI= 21

2) Twist constant= 1008

Ring frame is the final and very important machine for build the yarn onto bobbin in a form suitable for storage, transportation and processing. It is used to twist the drafted strand to form yarn of required count and strength. In this practical we calculate twist, twist constant of the ring frame. By this practical we come to know about the gearing diagram of ring frame. Special thanks to our teacher and his assistance for helping us.

You may also like:

  1. Ring Spinning Machine: Drafting System, Different Parts and Functions
  2. Calculation of Draft, Draft Constant of Ring Frame
  3. Ring Frame: Gearing Diagram, Calculation of Spindle Speed & Front Roller Speed
  4. Cotton Yarn Spinning Process Step by Step
  5. Material Passage Diagram of Ring Frame
  6. Reasons for Poor Quality in Ring Spinning
  7. Roving Frame or Simplex Machine: Description and Material Passage
  8. Maintenance Procedure of Ring Spinning Machines

Share this Article!

Leave a Comment