## Tuesday, 24 August 2010

### Warp Knitting | Caculation of Residual Yarn sheet on Warp Beam

In some cases on warp knitting fabric production practically ,we need to cut and replace the warp beam before the warp beams are finish and some yarn still remain wound up on the warp beams.The remain yarn sheet /residual yarn sheet on warp beam will be keep for next production order,for example due  a sudden change an order of fabric article or during the warping process warped yarn to much in the length or just for make a fabric samples or due another reason,whatever…

In this case we need to tape a yarn sheet on the warp beam,cut them  off and remove,however  we need  also to calculate  how many meters or kilo grams a yarn sheet remain on the warp beam for future used.Following are the formula to calculate the remain yarn sheet on warp beam for Warp Knitting.

First of all we need to know and to determine the current winding or the actual winding on warp beam,as follows ;

Actual Winding  = [( UA Actual – UI ) X full Winding ] : ( UA full – UI )

 UA = Outer Circumference of warp beam in mm UI = Inner Circumference of warp beam (empty barrel) in mm Example : UA actual = 1000 mm       | UI = 940 mm          | full winding = 10000

 Actual Winding = [( 1000 mm – 940 mm)  X 10000 ] : ( 1500 mm – 940 mm ) Actual Winding = 1071,4 winding for safety usually the warp knitting machine has to be stop when the 20 winding remain on the beam before finish,so we calculate 1071,4 – 20 = 1051,4 winding as an actual or current winding.
On the modern warp knitting machines from Karl Mayer which equipped with KAMCOS ,EBA or EBC  yarn let off system,the actual winding or current winding was displayed on the operator console of the machines,the above calculate is not  necessary to determine the actual winding of the warp beams.
See also "Winding Calculation for Warp Knitting"on previous article.
Now,we would like to convert from the current winding into the length of yarn sheet on the warp beams in meters uses following formula:

Warp Length (meter ) = [( UI + UA ) X winding ]  : 2000

2000 = refer to UI / UA and conversion from meter to millimeter.

 Example : UI = 940 mm | UA = 1000 mm Winding = 1051,4

 Warp Length (meter ) = [(940 mm + 1000 mm) x 1051,4]  : 2000 Warp Length (meter) =  1019,85 meters

To convert warp length in meter into weight of yarn sheet  remain on warp beam in kilograms ,uses following formula ;

Weight of yarn sheet per beam = Yarn Count (in Dtex) X threads per beam X warp length

 Example : Yarn Count (in dtex) = 44 dtex      |       threads per beam = 607 ends for warp knitting machine with gauge 28 E and 130 inches in  width ( six warp beams 21 x 30 or 30 x 30 )     |   warp length in meter = 1019,85 meter. Weigh of yarn sheet per beam in kg = 4,4 tex  X  607 ends  X 1019,85 meters Weigh of yarn sheet per beam in kg = 2,7 kg

The calculation above,is for cylindrical beams not for diabolo beam.
Please note ; the above calculation just for approximate, result may can be vary according to warping conditions,warping process and yarn properties it self.