Finding the weight of a given length of lap:
Lap is the output material of blowroom line when the input material for carding. Blowroom is the section where raw material such as compressed bale is feeded to convert them into sliver lap. Sliver lap is an uniform structured form of sliver which is got through opening, cleaning, blending and mixing operations. So sliver lap’s weight is very important to know after giving them for carding operation
Some mathematical calculation is given bellow which will clear your concept in cotton spinning.
Mathematical Example: 01
What is the weight of 12 yards of lap of hank-lap 0.00127 ?
Solution:
Length in yards
Weight in lbs = ...............................
840 x 0.0012
12
= .......................
840 x 0.0012
= 11.9lbs (ANS)
Mathematical Example: 02
1000 yards length of card sliver of 0.15 hank is packed in to a box. What is the net weight of sliver?
Solution:
1000
Weight in lbs = ........................
840 x 0.15
=7.937(ANS)
Mathematical Example: 03
A blowroom lap weighting net 45lbs.has 14 ounces per yard. Find the length of 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
= 51.43yards
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 is 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 revolution per minute while producing a lap of 0.0014 hank. 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
=1751lbs. (ANS)
