Calculate nominal production of a fleece-knitting machine per hour

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Calculate nominal production of a fleece-knitting machine per hour from the data given:

Machine Gauge                          18

Machine Dia                               30 inches

Number of Feeders for               60

Front yarn        

Number of feeders                     30

For loop yarn

Machine RPM                             28

Yarn Count                                26s for front

Yarn count for loop                    16s

Stitch length of                          4.5 mm

front yarn

           

Stitch length of                         2.5 mm

Loop yarn

           

Efficiency                                   85%

Solution:

Step one

First we will calculate number of needles and number of stitches produced in one revolution. This would help us in calculating the total length of yarn consumed in one revolution.

Number of needles = machine dia * gauge * p (3.14)

                             = 30* 18*3.14

                             =1696 (exact 1695 but needles are

                               always in even number so we will

                               take nearest even figure)

In this example we will calculate consumption of yarn in Kgs of both yarns and then we will add them to get final production per hour

Consumption of yarn for front knitting

Every needle is making one stitch on every feeder because machine is producing single jersey fabric (front of fleece).

Number of stitches produced in one revolution

= Number of needles * number of feeders  

= 1696*60

= 101760

This figure shows that machine is making 101760 stitches in one revolution.

Step Two

Length of stitch is 04.5 mm (stitch length is always calculated in metric system)

From this figure we can calculate yarn consumption in yards in one hour

Yarn Consumption (in yards) in one hour

= number of stitches * length of (mm) * RPM *60 (minutes)

                      1000(to convert mm into meters)

=101760 * 4.5 * 28 * 60

            1000

= 769305 meters or

= 841312 yards

Step Three 

In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count is known (see example 03).

Weight of cotton yarn = length of yarn

                                     Count * 840

                                    =   841312

                                         840 * 30

                                    = 38.52 pounds or

                                    = 17.43 Kilo grams

Efficiency           85%     = 14.85 Kilo grams

Answer: this machine will consume 14.85 Kgs of yarn to knit front of the fleece fabric in one hour at 85 % efficiency

Step Four

Yarn consumed for loop knitting (back of the fabric)

Every needle is making one stitch on every feeder because machine is producing single jersey fabric (front of fleece).

Number of stitches produced in one revolution

= Number of needles * number of feeders  

= 1696*30

= 50880

This figure shows that machine is making 50880 stitches in one revolution.

Note: that we have put 30 cones of course count for loops after every two feeders.

Step Five

Length of stitch is 2.5 mm (stitch length is always calculated in metric system)

From this figure we can calculate yarn consumption in yards in one hour

Yarn Consumption (in yards) in one hour

= number of stitches * length of (mm) * RPM *60 (minutes)

                      1000(to convert mm into meters)

=50880 * 2.5 * 28 * 60

            1000

= 213696 meters or

= 233696 yards

Step Six

In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count is known (see example 03).

Weight of cotton yarn = length of yarn

                                    Count * 840

                                    =   233696

                                         840 * 16

                                    = 17.39 pounds or

                                    = 7.89 Kilo grams

Efficiency        85%      = 6.70 Kilo grams

Step Seven

Now we can add both yarn consumed

Yarn for front                 14.85

Yarn for back                 6.70

 Total                            21.55

This machine can produce 21.55 Kgs fabric in one hour at 85% efficiency

All above discussion to elaborate the way to calculate the optimum production of a knitting machine. We have develop a equation which is useful in evey situation to calculate the optimum production capacity of a knitting machine at 85% efficiency.

For cotton count

Production in one hour =

Gauge * Dia * 3.14 * RPM *60 

* Stitch length (mm)  *1.0936 * 1 * 85

     1000 *840 * yarn count * 100