Blow room is the first stage of spinning where opening, cleaning, mixing and blending are done. The quality of yarn largely depends upon this stage. It also affects the CV%. Here trash content is also important. So, we have to know the calculations of blow room as well as the formulas. The important formulas are given below
Some important formulas for blow room section
Amount of trash removed
1. Cleaning efficiency of blow room section = ………………………………… X 100
Total amount of trash
Amount of trash in raw cotton – Trash in lap
= ……………………………………………………………… X 100
Amount of trash in raw cotton
Amount of trash removed
2. Cleaning efficiency of carding (%) = ……………………………… X 100
Trash in lap
Amount of Trash in lap – Amount of trash in Carding
= …………………………………………………………………….. X 100
Amount of Trash in lap
Trash in carded sliver (%)
3. Trash in lap (%) = …………………………………………. X 100
100 – Cleaning eff. (%)
Lap length (in gauge) Unit of weight
4. Lap hank = ………………………………….. X ………………………….
Unit of length Lap weight (Lbs)
Lap length (in gauge) 1 lb
= ………………………………… X ………………………………….
840 gauge Lap weight (Lbs)
5. Blow room production per hour = Surface speed of calendar roller (inch/min)
60
X ………………………….. X Eff. % X Waste% X No. of scatcher
36 X 840 X Hank
6. Lap length constant = Lap length X Change pinion
Lap length constant
Or, Change pinion = …………………………………
Lap length
7. Lap length = Surface speed of bottom calendar roller (In gauge)
= Circumference of bottom calendar roller (gauge) X Speed of bottom calendar roller
= (πD/36) X N Gauge (here, D= Dia of bottom calendar roller and N = Speed)
Knock off wheel Warm wheel
= (πD/36) X ……………………………….. X ……………………….. (Gauge)
Change wheel Single warm
8. Lap length constant (%) = Surface speed of bottom calendar roller (In gauge) X Speed from knock off wheel to bottom calendar roller
Knock off wheel Warm wheel
= (πD/36) X ……………………………. X …………………………
Change wheel = 1 Single warm
Conclusion
The delivery product of blow room is lap which is used in carding as feed material. So to make faultless we have to know the calculation and its formulas.
