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Some Useful Formulas for Drawing Frame

Some Useful Formulas for Drawing Frame

Md. Abu Sayed
Founder of Textile Apex
Pabna Textile engineering college, Pabna, Bangladesh
Email: sayed1952@facebook.com
Cell : +8801745214773




Draw Frame:
The draw frame is the quality filter of the spinning mill; errors in the draw frame sliver result inevitably in yarn defects. Hence, since quality can no longer be improved after the draw frame, the sliver quality at the last draw frame passage is of decisive importance: The slivers must be monitored in detail, metre by metre, to meet self-set quality standards. From a purely commercial view, the draw frame and drawing process is of little significance – it usually contributes less than 5% to production costs of the yarn. But from the point of view of quality of the yarn it is very much important.
Formulas for Drawing Frame
Draw frame
Essential Formula for Draw Frame 
                          Sliver length/Length unit
1. Sliver hank = …………………………..
                         Sliver weight/Weight unit

     Sliver length X Weight unit
= ………………………………
     Length unit X Sliver weight

      Sliver length (Gauge) X 7000
= …………………………………
      Sliver weight (Grain) X 840

                                      Draft constant
2. Technological draft = ………………
                                            DCP

      Front roller surface speed
= ……………………...………
      Back roller surface speed

     Front roller dia
= ……………………  X Gearing from back roller to front roller
     Back roller dia

        Feed material weight
= …………………………….   X {1 – (Waste% / 100)}
     Delivered material weight

= Actual draft X (100 – Waste%) /100

                           Delivered sliver hank X Doubling
3. Actual draft = ……………………………………
                                    Feed sliver hank

       Feed material weight
=……………………………
    Delivered material weight

      Delivered material length
= ……………………………
        Feed material length

       Total mechanical draft X 100
= …………………………………
               100 – Waste%

4. Delivered sliver weight = Feed sliver weight X Doubling/Draft

       Required draft          Required DCP          Present hank
5. …………………… = ……………….... = ……………………
       Present draft              Present DCP           Required hank

6. Production of machine = Front roller surface speed X Eff% X Waste% (inch/min)

= Front roller surface speed X 60/(36 X 840 X Hank) X Eff% X Waste% (lb/hr)


Draw Frame Problems and Solutions:
For giving the clear concept, i have given some examples. You can read it clear fully.

Problem-1. If any sliver hank 0.15, then what will be the weight per yard?

Here given,
  • Sliver hank = 0.15
  • Sliver length = 1 yard
  • Sliver weight/yd =?
Solution: 
We know,

                       Sliver length/Length unit
Sliver hank = ………………………………
                       Sliver weight/Weight unit

                            Sliver length          Weight unit
Or, Sliver hank = ……………  X  ………….……
                            Length unit           Sliver weight

                              Sliver length         Weight unit
Or, Sliver weight = ……………… X ……………………
                               Length unit          Sliver hank

= 1/840 X 1/0.15 = 0.0079 lb

= 0.0079 X 7000 Grain               (7000 grain = 1 lb)

= 55.30 Grain (ANS).

Problem-2. A drawing frame producing 0.18 hank sliver with DCP of 58T. If we want to produce 0.17 hank sliver, then calculate the required DCP.

Here given,
  • Present DCP of drawing frame = 58
  • Present hank of drawing frame = 0.18
  • Required hank = 0.17
  • Required DCP =?
Solution:
We know,

  Present hank             Required DCP
………………… = …………………………
  Required hank           Present DCP

Or, Required DCP = Present DCP X Present hank/Required hank

= 58 X 0.18/0.17 = 61.41 = 61T (ANS).

Problem-3. A machine’s front roller dia is 11/10”, Sliver hank is 0.16, front roller speed is 465 r.p.m and eff.% is 90%, then what will be the production per shift of the machine?

Here given,
  • Front roller dia = 11/10”
  • Front roller speed = 465 r.p.m
  • Sliver hank = 0.16
  • Eff. of machine = 90%
  • Production/shift =?
Solution:

We know that,

Production = Surface speed of front roller X Eff.%

= π X Dia X Speed X Eff.%

= 3.14 X 11/10 X 465 X 90/100 inch/min

= 3.14 X 11/10 X 1/(36 X 840 X 0.16) X 465 X 60 X 8 X 90/100 lb/min

= 143.40 lb/shift (ANS).

Problem-4. To get 0.17 hank sliver from a drawing machine by feeding 0.14 hank carded sliver (No. of carded sliver is 6), calculate the required DCP. Draft constant is 234.

Here given,
  • Doubling = 6
  • Feed or Carded sliver hank = 0.14
  • Delivery or Drawn sliver hank = 0.17
  • Draft constant of the machine = 234
  • DCP =?
Solution:
We know,

Draft = (Deliver sliver hank X Doubling) / Feed sliver hank

= (0.17 X 6) / 0.14 = 1.02 / 0.14 = 7.29

Again,

DCP = Draft constant/Draft = 234 / 7.29 = 32.10 = 32T (ANS).

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