Calculation of Twist, Twist Constant of Roving Frame or Speed Frame Machine

Last Updated on 28/02/2021

Name of the experiment:
Calculation of twist, twist constant of the roving frame or speed frame or simplex machine.

Twist is the spiral turns given to a yarn to increase the strength of the yarn. But in speed frame machine vary small amount of twist is given to the roving to make it able to wound onto a bobbin. For a fibrous material twist is measured by the parameter twist per inch (TPI), twist per centimeter or twist per meter (TPM). For the cotton sample twist is measured by TPI.

In speed frame machines twist per unit is varied with the variation of raw material and its different parameters. This variation of twist is inserted by changing a wheel that is connected with the main driving shaft named twist change pinion (TCP). And the multiply of TCP and TPI, present in a machine is called twist constant. This value is applicable for any required twist with corresponding TCP. So we can find out the required TCP to get a given TPI.

The generalize formula is as below:

formula of twist constant


  1. Front roller carrier wheel: 80T(A)
  2. Twist constant change pinion carrier: 30T(B)
  3. Twist constant change pinion: 30T(C)
  4. Twist change pinion: 28T(D)
  5. Sprocket wheel: 34T(E)
  6. Sprocket pinion: 36T(F)
  7. Spindle carrier wheel: 40T(G)
  8. Spindle wheel: 22T(H)

Gearing Diagram of Roving Frame or Speed Frame:

gearing diagram of speed frame
Fig: Gearing diagram of speed frame


calculation of roving frame machine


  1. Twist per inch TPI → 1.56
  2. Required TCP → 33

Roving frame or Speed frame is the first machine which enables the winding of the fibrous material on to a package. From this machine the fiber gets a circular shape which is very advantageous to be used in ring spinning. So the importance of this machine is very much. In this experiment we indicate different gearing diagram of the twist inserting portion; specify it and calculate twist and twist constant of the roving frame. We found a satisfactory result. So the experiment is a successful one.

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