Some Useful Formulas for Drawing Frame

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, meter by meter, to meet self-set quality standards. From a purely commercial view, the draw frame and drawing process are of little significance – it usually contributes less than 5% to the production costs of the yarn. But from the point of view of the quality of the yarn, it is very much important. In this article, we will discuss some useful formulas for drawing frame.

drawing frame machine
Fig: Drawing frame machine

Some Useful Formulas for Drawing 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:

Forgiving a 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               (As 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).

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

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