**Introduction**

**Combing** is the removing process of short fibers, neps & impurities of carded sliver and to make the fiber more parallel, uniform & straight by using a comb machine or comb associated by knives, brushes and rollers. Combing is necessary for better yarn appearance and regularity. Longer fibers are finer than shorter fibers. After combing higher count (uniform & finer sliver) is possible to keep minimum no of fiber in yarn diameter. So, calculations play an important role in combing. Some important calculations (Actual Draft & Mechanical Draft, Draft Constant, DCP, Comber Noil%, Machine Production, Production Constant, Bett Tension, sliver Hank etc.) of Comber machine are discussed below.

**Some Important Conversion Factors for Comber Machine Production Calculations:**

- 36 inch = 3 Feet = 1 Yard;
- 1 Meter = 1.0936 Yards;
- 1 Pound(lb) = 453.6 Gram = 16 Ounce (Oz);
- 1 Lea = 120 Yards;
- 840 Yard = 7 Lea = 1 Hank;
- 1 Pound (lb) = 7000 Grains;
- 1 Meter = 39.37 Inch;
- 1 inch = 2.54 cm;
- 1 cm = 10 mm;
- 1 Kg = 2.205 Pound (lb)
- Count means the number of 840 yards length that weight exactly 1 pound (lb)
- KTex = Number of kilograms per 1000 meters.

**Lap Former and Comber Machine Production Calculations with Formula:**

**………………………..Delivery Count x No of Doubling**

**1. Actual Draft = ————————————————————————-**

**…………………………..Feed Count x No of Delivery**

**……………………………………………………(100 – Noil Extraction %)**

**2. Mechanical Draft = Actual Draft x ———————————————-**

**…………………………………………………………………100**

**3. Draft Constant = Mechanical Draft x DCP**

**Example:** Find out required DCP to produce 3.4 Ktex sliver from 64 Ktex comber lap, the comber machine particulars are as the following- no of head = 8, no of delivery = 2, noil extraction = 15%, draft constant = 1698.

**Solution:**

Here given,

Feed Count = 3.4 Ktex

Delivery Count = 64 Ktex

No of Doubling = 8

No of Head = 2

Noil Extraction% = 15

Draft Constant = 1698

……………………..Delivery Count x No of Doubling

Actual Draft = ——————————————————————–

………………………..Feed Count x No of Delivery

….64 x 8

= ————– = 75.3

…3.4 x 2

………………………………………………….100 – Noil%

Mechanical Draft = Actual Draft x ——————–

………………………………………………………100

…………..100 – 15

= 75.3 x —————–

……………..100

= 64

Draft Constant = Mechanical Draft x DCP

…………………Draft Constant

Or, **DCP** = —————————————–

………………..Mechanical Draft

…1698

= ————— = 26.53≈ 27T **(Ans)**

…..64

**4. Production per Day = Nip/Min x Feed/Nip x No of Head x Feed Lap Wt. x Efficiency x Noil% x 60 x 24**

**………………………………………….Required Production**

**5. No of Comber Required = ——————————————————–**

**…………………………………………..Actual Production**

**Example:** Calculate the production per day of a **combing machine** running with following particulars – feed lap wt = 1100 grains/yard, nips/min = 400, no of combing head = 8, Noil extraction = 17%, feed/nip = 5 mm, efficiency = 90%. Also find out the no of modern comber m/c to produce 10000 lb/day.

**Solution:**

Nip/Min = 400

……………………………………….5

Feed/Nip = 5 mm = ————————-= 0.005468 yard

……………………………..10 x 2.54 x 36

No of Head = 8

Feed Lap Wt = 1100 grains/yard

= 1100/7000 lbs/yard

= 0.1571 lbs/yard

Efficiency = 90% = 90/100 = 0.9

Noil% = 17% = 100-17/100 = 0.83

**Production per Day** = Nip/Min x Feed/Nip x No of Head x Feed Lap Wt. x Efficiency x Noil% x 60 x 24

= 400 x 0.005468 x 8 x 0.1571 x 0.9 x 0.83 x 60 x 24lbs/day/comber

= 2956.9lbs/day/comber **(Ans)**

Here, Required Production = 10000 lbs/day

Actual Production = 2956.9 lbs/day

**No of Comber M/C Required** = 10000/2956.9 = 3.38 ≈ 3 **(Ans)**

**…………………Nips/Min x Feed/Nip x No of Head x Lap Wt. x Effi. x Noil% x 60**

**6. Production/hr = ———————————————————————————————**

**……………………………………………………1000 x 1000**

**Example:** The cylinder of a 6 head comber is running at a speed of 150 nips per minute and each nip feeds 0.185″ lap. The hank of lap is 0.0166. Calculate the production of comber in hours at 75% efficiency and 12% waste.

**Solution:**

Here Given,

Nips/Min = 150

Nip/Feed = 0.185”

= 0.185 x 2.54 x 10 = 4.699 mm

Lap Hank = 0.0166

= 32.53 gm/yard

= 29.745 gm/m (Lap Wt.)

Efficiency = 75% = 0.75

Waste/Noil% = 12% = 100-12/100 = 0.88

No of Comber Head = 6

……………………….Nips/Min x Feed/Nip x No of Head x Lap Wt. x Effi. x Noil% x 60

**Production/hr** = ————————————————————————————————–

………………………………………………………………….1000 x 1000

…150 x 4.699 x 6 x 29.745 x 0.75 x 0.88 x 60

= ————————————————————— kg

……………………..1000 x 1000

= 4.98 kg **(Ans)**

**7. Production per Shift = Feed/Min x Lap Wt x Efficiency x noil% x No of Head x 60 x Shift x Bett Tension**

**Example:** Calculate the production of comber machine per shift. Using the following particulars-

Lap Hank = 70 KTex

Nips/Min = 350

Feed/Nip = 5 mm

Bett Tension = 12 %

Noil % = 18 %

Efficiency (%) = 90 %

No. Of Head = 8

Shift Time = 8 Hours

**Solution:**

Here Given,

Lap Hank = 70 KTex

…70 x 1000

= —————– = 70 gm/m

…….1000

So, Lap Wt. = 70 gm/m

Bett Tension % = 12

…………………………..Bett Tension in%

Bett tension = 1 + ———————————

…………………………………..100

…………..12

= 1 + ————- = 1.12

…………100

Here given,

Feed/Nip = 5mm

Nips/Min = 350

Feed/Min = Feed/Nip x Nips/Min

= 5 x 350 mm

= 1750 mm

= 1.75 Meter

Efficiency = 90% = 0.9

Noil% = 18% = (100-18)/100 = 0.82

Also Given,

No of Head = 8

Shift Time = 8 hrs.

**Production per Shift** = Feed/Min x Lap Wt x Efficiency x noil% x No of Head x 60 x Shift x Bett Tension

= 1.75 x 70 x 0.9 x 0.82 x 8 x 60 x 8 x 1.12

= 388813.824 grams

= 388.813 kgs **(Ans)**

**8. Production constant = π x Roller Dia (D) x Coiler Calendar Roller RPM (N)**

**9. Production per Shift = Product Constant x Sliver Wt. x Efficiency x 60 x 8**

**Example:** Find out the production constant and production/shift in a comber machine as per following parameters:

Coiler calendar roller speed = 120 rpm

Roller radius = 1.25″

Delivery sliver wt. = 72 grains/yd

Efficiency (%) = 90%

**Solution:**

Here Given,

Coiler Calendar Roller Speed = 120 RPM

Roller Radius, r = 1.25”

Delivery Sliver Weight = 72 Grains/yard = 72/7000 = 0.0102857 lb/yard

Efficiency = 90% = 0.9

**Production Constant** = πDN = π x 2r x N

= 2 x 3.1416 x 1.25 x 120 inch/min

= (2 x 3.1416 x 1.25 x 120)/36 yards/min

= 26.18 yards/min** (Ans)**

**Production per Shift** = Product Constant x Sliver Wt. x Efficiency x 60 x 8

= 26.18 x 0.0102857 x 0.9 x 60 x 8 lbs

= 116.33 lbs **(Ans)**

**………………………………………………………………….π x CCR RPM x CCR Dia**

**10. Surface Speed of Coiler Calendar Roller = ———————————————-**

**………………………………………………………………………………39.37**

**……………………………………….7000**

**11. Sliver Hank = ——————————————————-**

**……………………….Sliver wt. (grains/yd) x 840**

**……………………….SS of CCR x 0.59 x No of Head x Efficiency x 60 x 8**

**12. Production = ————————————————————————————**

**………………………………….Sliver Hank (Ne) x 1000 x 100**

**Example:** Calculate the m/c production per shift with the help of following particulars-

- Coiler Calendar Roller RPM = 125
- Coiler Calendar Roller Dia = 2.25”
- Delivery Sliver wt. = 70 Grains/yard
- No of Heads = 8
- Efficiency = 90%

**Solution:**

………………………………………………………………π x CCR RPM x CCR Dia

Surface Speed of Coiler Calendar Roller = ———————————————–

…………………………………………………………………………….39.37

…3.1416 x 125 x 2.25

= ——————————- meters/min

………….39.37

= 22.44 meters/min

………………………………..7000

Sliver Hank = ————————————————

…………………Sliver wt. (grains/yd) x 840

……7000

= —————– = 0.119 Ne

…70 x 840

…………………………………….SS of CCR x 0.59 x No of Head x Efficiency x 60 x 8

**Production per shift** = ———————————————————————————-

……………………………………………………Sliver Hank (Ne) x 1000 x 100

…22.44 x 0.59 x 8 x 90 60 x 8

= ———————————————- kgs

…….0.119 x 1000 x 100

= 384.5 kgs **(Ans)**

**………………………….Wt. of Noil**

**13. Noil% = ————————————————– x 100**

**………………..Wt. of Noil + Wt. of Sliver**

**Example:** Find out the Noil%, If the sliver weight is 70 grains/yard and the wt. of noil is 0.89 gram/meter.

**Solution:**

Here given,

Wt. of Noil = 0.89 gram/meter

Wt. of Sliver = 70 grains/yard

Sliver Wt. = 70 grains/yard

= 70/7000 lb/yard

= 70 x 453.6/7000 gram/yard

…70 x 453.6 x 39.37

= —————————- gram/meter

……….7000 x 36

= 4.96 gram/meter

……………………….Wt. of Noil

Noil% = —————————————— x 100

…………..Wt. of Noil + Wt. of Sliver

……….0.89

= ——————– x 100

…0.89 + 4.96

= 15.21% **(Ans)**

**Conclusion**

I have tried to explain & solve the machine production calculation and other calculations formulas with examples of Comber Machine (Lap Former) through this article. Hope this article will be helpful for those who are new to the **spinning mill** or those who are students.

**Author of this Article:**

Md. Imran Hossain

B.Sc. in Textile Engineering

Shahid Abdur Rab Serniabat Textile Engineering College, Barisal.

Email: [email protected]

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