# Draft, Draft Constant and Production Calculation of Drawframe Machine

Last Updated on 17/02/2022

### Draft, Draft Constant and Production Calculation of Drawframe Machine

Ranishka Yeashan
University of Moratuwa, Sri Lanka
Email: ranishkashn7@gmail.com

Drawframe:
Drawframe is a very critical machine in the spinning process. Drawing is the operation by which slivers are blended, doubled and leveled. In short staple spinning the term is only applied to the process at a draw frame. It’s influence on quality, especially on evenness is very big. If drawframe is not set properly, it will also result in drop in yarn strength and yarn elongation at break. The faults in the sliver that come out of draw frame cannot be corrected. It will pass into the yarn.

Gearing Diagram of Drawframe Machine:
X gear is a one gear and for the drawing purpose it is separated as two gears.

Intermediate and Total Mechanical Drafts

Let motor rpm is N

Finding roller rpm according to gear system,

Calender Roller rpm = (N×130)/121
Front Roller rpm = (N×130×44×48) / (121×48×30)
Second Roller rpm = (N×130×23×71) / (121×77×58)
Third Roller rpm = (N×130×23×71×37×47) / (121×77×58×59×30)
Back Roller rpm = (N×130×44×67×75×TDC×44×52) / (121×67×75×52×114×52×54)

Intermediate Drafts
Since the roller diameters are equal in main drafting zone, draft is proportionate to the rollers rpm

Front Roller and Second Roller,

Draft = (Front Roller rpm) / (Second Roller rpm)
Draft =1.575N/0.392N
Draft = 4.011

Second Roller and Third Roller,

Draft = (Second Roller rpm) / (Third Roller rpm)
Draft = 0.392N / 0.386N
Draft = 1.015

Third Roller and Back Roller,

In this moment TDC is equal to 40T

Draft = (Third Roller rpm) / ( Back Roller rpm)
Draft = 0.386N/0.26N
Draft = 1.485

So the Total Draft without Tension draft from the Calender rollers,

Total Draft = 4.011 × 1.015 × 1.485 = 6.046

Calender Roller Draft

Tension Draft = (Calender Roller surface speed) / (Front Roller surface speed)
Tension Draft = (1.074N×π×51) / (1.575N×π×35)
Tension Draft = 1

Production of Machine per shift of 8 hrs at 85% efficiency where the sliver hank to be 3700 tex

Output per minute = Calender Roller surface speed (m/min)
Output per minute =1.074×1509×π×(51/1000) × (3700/1000) × (1/1000) kg
Output per shift = 0.9607×60×8 kg
Output per shift with 85% = 461.165×0.85 kg
Output per shift, 85% on both heads = 392×2 kg
Output per shift, 85% on both heads = 784 kg

Draft Constant
When TDC is a changeable gear wheel, we get the total draft as

Total Draft = 4.011 × 1.015 × 59.4/TDC
Total Draft = Draft Constant × Changeable Gear wheel
Total Draft = 242×1/TDC
Draft Constant = 242

Production Constant
Production Constant is calculated under motor rpm of Nm, 85% efficiency and C tex of output sliver per hour.

Production = 1.074×Nm×π× (51/1000)×(C/1000)×(1/1000)×60×0.85×2 kg/hr
Production = 1.755×1/10^5×Nm×C kg/hr
Production Constant = 1.755×1/10^5

Production Calculation of Drawframe:

……………………………….FR surface speed (rpm) x 1.0936 x 60 x 8 x Efficiency
Production in kg = ————————————————————————————–
……………………………………………………..840 x count x 2.204

Draft constant = Draft x Draft wheel

Problem-01:

If, Delivery roller speed = 600 m/min
Sliver Hank = 0.110 Ne
Wastage = 0.5%
Efficiency = 85%
Production = ?

Solution:

Production (kg/hr) = (600 x 1.0936 x 60 x 0.85) / (840 x 0.110 x 2.2046)
=163.74 kg/hr (Ans)

Problem-02:

Find out the DCP  if,

Feed Sliver weight = 62 gr/yd,
Delivery Sliver weight = 60 gr/yd sliver,
Delivery speed = 400 m/min
No of doubling = 8
Draft constant = 320

Solution:

We know that,

Draft / Doubling = Feed wt. / Delivery wt.

Draft = (Feed wt. x Doubling) / Delivery wt.
= (62 x 8) / 60
= 8.267

Again we know that,

Draft = Draft constant / DCP

DCP =  Draft constant / Draft
= 320/ 8.267
= 37.99 T
≈38 T

You may also like: