Tuesday, August 9, 2011

For Filament yarn : Calculate nominal production of a single jersey-knitting machine per hour

Learn Apparel Merchandising, Learn Fashion design.
Calculate nominal production of a single jersey-knitting machine per hour from the data given:
Machine Gauge              28
Machine Dia                   26 inches
Number of Feeders        120
Machine RPM                 30
Yarn Denier                   75
Stitch length                  4.5 mm            
Efficiency                       85%
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)
                             = 26* 28*3.14
                             = 2286 (exact 2285.92 but needles are
                                always in even number so we will
                                take nearest even figure)

Number of stitches produced in revolution
 Every needle is making one stitch on every feeder because machine is producing single jersey fabric (full knit fabric).
Number of stitches produced in one revolution 
= Number of needles * number of feeders  
= 2286*120
= 274320
This figure shows that machine is making 274320 stitches in one evolution.

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)

= 274320 * 4.5 * 30 * 60
= 2221992 meters                                                                     

Step Three 

In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count/denier is known (see example 05).

Weight of filament in grams = Length in meters * denier 


                                                 = 2221992*75 
            Answer                          =18516 grams or
                    =18.516 Kgs                           

Efficiency           85%       = 18.516*85%
                                       =15.74 Kgs
Answer: this machine can produce 15.74 Kgs fabric in one hour at 85 % efficiency                    

Note: if we are producing any textured fabric, like fleece, then we use two different yarns at different feeders and ultimately stitch length is also different. In such case we should calculate separately consumption of different yarn at different feeders. Following example will help in calculating production in case of use of more than one kind yarn.


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