# Some Essential Calculations of Cotton Spinning

Finding the weight of a given length of lap:
Lap is the output material of the blow room line when the input material for carding. Blow room is the section where raw material such as compressed bale is fed to convert them into sliver lap. Sliver lap is a uniform structured form of sliver which is got through the opening, cleaning, blending, and mixing operations. So sliver lap’s weight is very important to know after giving them for carding operation. In this article, we will discuss some essential calculations of cotton spinning.

### Some Essential Calculations of Cotton Spinning

Some mathematical calculation is given below which will clear your concept in calculations of cotton spinning.

Mathematical Example: 01
What is the weight of 12 yards of the lap of hank-lap 0.00127?

Solution:

………………………..Length in yards
Weight in lbs = ………………………….
………………………….840 x 0.0012

………….12
= …………………..
….840 x 0.0012

= 11.9 lbs (ANS)

Mathematical Example: 02
1000 yards length of card sliver of 0.15 hank is packed into a box. What is the net weight of the sliver?

Solution:

…………………………….1000
Weight in lbs = ………………….
……………………….840 x 0.15

=7.937(ANS)

Mathematical Example: 03
A blow room lap weighting net 45 lbs.has 14 ounces per yard. Find the length of the lap and how long does it last on a card whose 2 ¼” feed roller rpm is 1.25.

Solution:

…………………………45 x 16
Length of lap = ………………
……………………………14

= 51.43 yards

Length of lap fed to card per minute = 22/7 x 9/4 x 1.25/36 yards

Time of one-lap running on the card = 51.43 ÷ (22/7 x 9/4 x 1.25/36) minutes
= 3 ½ hours (approx) (ANS)

Mathematical Example: 04
Find the actual draft and mechanical draft of a finisher scutcher which is using breaker laps weighting 15 ounces per yard and produces 14 ounces per yard. The droppings beneath the beater are 1.2%.

(Note; Four breaker laps and doubled on the finisher scutcher machine)

Solution:

………………………15 x 4
Actual draft = ……………..
…………………………14

= 4.29

……………………………….15 x 4 x 100
Mechanical draft = ……………………….
…………………………………14 x 101.2

= 4.23 (ANS)

Mathematical example: 05
The bottom calendar roller of 7” diameter makes 7.8 revolutions per minute while producing a lap of 0.0014 hanks. Find out the production per shift of 8 hours if the efficiency of the machine is 90%.

Solution:

………………………………………………………………7.8 x 60 x 8
100% per shift production = 22/7 x 7/36 x …………………….. lbs
………………………………………………………………840 x 0.0014

……………………………………………………7.8 x 60 x 8           90
Actual production = 22/7 x 7/36 x …………………….. x ………lbs
……………………………………………………840 x 0.0014       100

=1751 lbs. (ANS)

```Author of this Article:
Amit Kumar Das
Founder of "টেক্সটাইল ম্যানিয়া" Blog
Pabna Textile engineering college, Pabna, Bangladesh
Cell: 01770 456240
Email: [email protected]```

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